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Molecular and Cellular Biology, October 2001, p. 6782-6795, Vol. 21, No. 20
Laboratories of Biochemistry and Molecular
Biology1 and Mass Spectrometry and
Gaseous Ion Chemistry,2 The Rockefeller
University, New York, New York 10021
Received 18 May 2001/Returned for modification 21 June
2001/Accepted 13 July 2001
GCN5 is a histone acetyltransferase (HAT) originally identified in
Saccharomyces cerevisiae and required for
transcription of specific genes within chromatin as part of the SAGA
(SPT-ADA-GCN5 acetylase) coactivator complex. Mammalian cells have two
distinct GCN5 homologs (PCAF and GCN5L) that have been found in
three different SAGA-like complexes (PCAF complex, TFTC
[TATA-binding-protein-free TAFII-containing complex], and
STAGA [SPT3-TAFII31-GCN5L acetylase]). The
composition and roles of these mammalian HAT complexes are still poorly
characterized. Here, we present the purification and characterization
of the human STAGA complex. We show that STAGA contains homologs of
most yeast SAGA components, including two novel human proteins with
histone-like folds and sequence relationships to yeast SPT7 and ADA1.
Furthermore, we demonstrate that STAGA has acetyl coenzyme A-dependent
transcriptional coactivator functions from a chromatin-assembled
template in vitro and associates in HeLa cells with
spliceosome-associated protein 130 (SAP130) and DDB1, two structurally
related proteins. SAP130 is a component of the splicing factor SF3b
that associates with U2 snRNP and is recruited to prespliceosomal
complexes. DDB1 (p127) is a UV-damaged-DNA-binding protein that
is involved, as part of a complex with DDB2 (p48), in nucleotide
excision repair and the hereditary disease xeroderma pigmentosum. Our
results thus suggest cellular roles of STAGA in chromatin modification,
transcription, and transcription-coupled processes through direct
physical interactions with sequence-specific transcription activators
and with components of the splicing and DNA repair machineries.
In eukaryotes, genomic DNA is
packaged by histones into nucleosomes that further fold to form
higher-order chromatin structures. Eukaryotic cells have evolved two
major enzymatic mechanisms to modify chromatin structure: (i)
ATP-dependent nucleosome remodeling by multiprotein complexes that use
the energy of ATP hydrolysis to alter the association of core
histones with DNA and (ii) covalent modifications of core histones,
including acetylation, that regulate core histone interactions with
either DNA, adjacent nucleosomes, or other regulatory proteins
(reviewed in references 7, 39, 64, and 74).
Reversible acetylation of specific lysine residues within the
N-terminal tails of nucleosomal core histones has long been correlated
with changes in chromatin that occur during transcription, replication,
and DNA repair in vivo (reviewed in references 7, 61, and 65). Significant progress in
understanding the role of nuclear histone acetylation came from the
findings that the Saccharomyces cerevisiae transcription
coactivator GCN5, and more recently other yeast and metazoan
transcription cofactors, are histone acetyltransferases (HATs) and that
several transcription corepressor complexes have histone deacetylases
as integral subunits (reviewed in references 4 and
10). HATs differ in substrate specificity and may also
modify nonhistone regulatory proteins, as originally demonstrated for
p53 acetylation by p300 (27). Many nuclear HATs are also
part of large multiprotein assemblies. These include yeast SAGA
(SPT-ADA-GCN5 acetylase), ADA, NuA3, NuA4, and Elongator complexes,
yeast and metazoan TFIID complexes, and human TFTC (TATA-binding
protein [TBP]-free TBP-associated factor II
[TAFII]-containing complex), PCAF, STAGA
(SPT3-TAFII31-GCN5L acetylase), TIP60, and TFIIIC
complexes (reviewed in references 10 and
24).
In yeast, GCN5 is an integral subunit of at least two distinct
multiprotein HAT complexes, the ADA and SAGA complexes, that acetylate
histones H3 and H2B within nucleosomes (25). The yeast SAGA complex is composed of (i) ADA adapter (coactivator) proteins (ADA1, ADA2, ADA3, ADA4 [GCN5], and ADA5 [SPT20]), (ii) SPT
proteins (SPT3, SPT7, SPT8, and SPT20 [ADA5]), (iii) a subset of the
yeast TAFIIs (yTAFIIs)
(yTAFII17/20, yTAFII25,
yTAFII60,
yTAFII61/68, and
yTAFII90), and (iv) a protein, Tra1, that is
structurally related to members of the
ATM/DNA-PK/phosphatidylinositol 3-kinase family (reviewed in
references 10, 24, and 78). The
ADA complex shares GCN5, ADA2, and ADA3 with SAGA but lacks all other SAGA subunits and has ADA-specific components (20). The
SAGA complex, but not the ADA complex, interacts directly with various activators and potentiates activation domain-specific transcription in
an acetyl coenzyme A (acetyl-CoA)-dependent manner on nucleosomal arrays in vitro (34, 72, 76).
Mammalian homologs of yeast GCN5 include PCAF and GCN5L (12, 62,
79, 82). PCAF and GCN5L proteins are encoded by distinct genes,
and their expression is differential and complementary in various
tissues (79, 82). However, GCN5L is essential for mouse
development, whereas PCAF is dispensable (80, 81). Human GCN5L (hGCN5L) and PCAF form part of three distinct multiprotein HAT
complexes: PCAF complex (54), TFTC
(8), and STAGA (46). While still incompletely
characterized, these human HAT complexes preferentially acetylate
histone H3 and have related but not identical subunit compositions. All
contain homologs of yeast SAGA subunits and a subset of
TAFIIs that were originally found in TFIID but clearly lack TBP (reviewed in reference 24). Apart from a
TFIID-like function for TFTC in transcription from "naked" DNA
templates in vitro (77), the functions of these human
TAFII-HAT complexes remain still largely unknown. More
generally, the recent observations that yeast and metazoan
transcriptional adapters and HATs are within large multiprotein
complexes raises important questions as to the role(s) of the remaining
protein subunits and whether HAT complexes have additional functions.
In the present study we report the identification of most of the
protein subunits of the human STAGA complex. These include novel human
proteins similar to yeast SAGA components. In addition, we show that
human STAGA preferentially acetylates histone H3 within nucleosomes and
mediates in vitro transcriptional activation by the chimeric Gal4-VP16
activator on a chromatin template through direct physical interactions
with the VP16 activation domain. Furthermore, we demonstrate an
association of STAGA in HeLa cells with spliceosome-associated protein
130 (SAP130) and with UV-damaged-DNA-binding factors, suggesting the
possibility of additional functions for STAGA in transcription-coupled
pre-mRNA splicing and DNA damage repair in vivo.
Plasmids.
pFH-IRESneo was obtained by insertion of a Kozak
consensus ATG and in-frame FLAG- and hemagglutinin (HA)
epitope-coding sequences between the EcoRV and
NotI sites of pIRES1neo (Clontech). hSPT3 and
TAFII31 cDNAs were cloned into pFH-IRESneo to
obtain, respectively, pFH:SPT3-IRESneo and pFH:TAF31-IRESneo.
pGEX-5X-3-DDB1 (44) and pBJ5-FLAG-p125/DDB1
(33) have been described previously.
Stable cell lines, extract preparation, and protein complex
purification.
HeLa S cells were transfected with pFH:SPT3-IRESneo
or pFH:TAF31-IRESneo and selected with 500 µg of G418 (GIBCO) per ml. Single G418-resistent colonies expressing FLAG-HA-tagged proteins were
expanded for nuclear extract preparation. Nuclear extracts were
adjusted to 300 mM KCl (BC300) and 0.05% NP-40 and rotated with
M2-agarose (Sigma) at 4°C for 3 to 6 h. After extensive washes with BC300-0.05% NP-40, proteins were eluted with 0.3 mg of FLAG peptide per ml in BC100-0.05% NP-40. M2 eluates were incubated with
anti-HA antibody (12CA5; BAbCO) beads for 4 h at 4°C, the beads were washed extensively with BC400-0.1% NP-40, and proteins were eluted at 30°C with 2 mg of HA peptide per ml in BC100-0.1% NP-40. Alternatively, M2 eluates, adjusted to BC60-0.05% NP-40, were
fractionated on S-Sepharose (Pharmacia). For purification of a STAGA
complex lacking SAP130 (STAGA-s), nuclear extracts were loaded on a
S-Sepharose column, the column was washed with BC100-0.05% NP-40, and
bound proteins were step eluted with BC200-0.05% NP-40 and
BC400-0.05% NP-40. The BC400 protein eluate was incubated with
M2-agarose, the resin was washed extensively with BC320-0.05% NP-40,
and bound proteins were eluted as described above.
Protein identification by MS.
In-gel tryptic digests of
proteins from M2 affinity-purified STAGA resolved on sodium dodecyl
sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels were
analyzed by matrix-assisted laser desorption ionization-time-of-flight
(mass spectrometry) (MALDI-TOF [MS]), liquid chromatography-ion
trap-tandem MS, and MALDI- and nanospray-quadrupole-quadrupole TOF-MS. The mass spectral data were used to search the National Center for Biotechnology Information (NCBI) nonredundant and
expressed sequence tag databases as previously described (reference
41 and references therein). The peptides identified
are as follows: for STAF400 (TRRAP), GLSVDSAQEVK,
NPADSISHVAYR, TATGAISAVFGR, LVEDNPSSLSLVEIYK, LAVDLSEVVIK, and
YLQFVAALTDVNTPDETK; for STAF130 (SAP130),
LPPNTNDEVDEDPTGNK, NFGDQPDIR,
DYIVVGSDSGR, NVSEELDRTPPEVSK, MQGQEAVLAMSSR, AGNGQWASWIR,
LTISSPLEAHK, SVAGGFVYTYK,
SWLSYSYQSR, IVILEYQPSK,
ILELLRPDPNTGK, TVLDPVTGDLSDTR,
IVPGQFLAVDPK, TPVEEVPAAIAPFQGR, FLAVGLVDNTVR, AEVIMNYHVGETVLSLQK,
NENQLIIFADDTYPR, WVTTASLLDYDTVAGADK, HGLEVSEMAVSELPGNPNAVWTVR, FSNTGEDWYVLVGVAK,
and LGAVFNQVAFPLQYTPR; for STAF97 (hGCN5L),
QIPVESVPGIR, TLILTHFPK, and
TLPENLTLEDAK; for STAF65 Immunoprecipitations and GST pull-down assays.
Nuclear
extracts from either FLAG-HA double-epitope-tagged hSPT3 (fh:SPT3) or
control HeLa cells were mixed with M2-agarose in BC100, the
suspension was rotated for 3 h at 4°C, and the beads were washed
extensively with BC150-0.05% NP-40. Proteins were eluted with 0.3 mg
of FLAG peptide per ml. Whole-cell extracts of HeLa cells transiently
transfected with pBJ5-FLAG/DDB1 were adjusted to BC200 and rotated with
M2-agarose. After extensive washes with BC200-0.05% NP-40 and
BC100-0.05% NP-40, proteins were eluted with 0.5 mg of FLAG peptide
per ml. Bacterially expressed glutathione S-transferase
(GST), GST-DDB1, and GST-VP16 proteins immobilized on
glutathione-agarose were incubated for 1 to 3 h at 4°C in
BC100-0.05% NP-40 with nuclear extracts or affinity-purified STAGA;
the resins were washed extensively with BC150-0.1% NP-40 (unless
otherwise indicated), and bound proteins were eluted with Sarkosyl (0.2 to 0.5%).
HAT assay, chromatin assembly, and transcription.
HeLa core
histones and native nucleosomes were purified as described previously
(14, 46). HAT assays with 1 µg of core histones and
nucleosomes were performed and analyzed on SDS-PAGE gels as described
elsewhere (46). The S190 extract was prepared from
Drosophila embryos 0 to 4 h after fertilization
(37). The G5-MLP plasmid, which contains a 390-nucleotide
G-less cassette, was assembled into chromatin with purified HeLa core
histones in the S190 extract essentially as described previously
(5). After chromatin assembly, Sarkosyl (0.05% final
concentration) was added, and chromatin was immediately purified by gel
filtration on a Sepharose CL-4B column (0.7 by 30 cm)
equilibrated with EX-20 buffer (10 mM HEPES [pH 7.5], 20 mM KCl, 0.5 mM EDTA, 1.5 mM MgCl2, 1 mM dithiothreitol
[DTT], 10% glycerol, 0.01% NP-40). Micrococcal nuclease digestion
was performed as previously described (11). In vitro
transcription reactions were performed as schematized in Fig. 4C. Naked
or chromatin-assembled G5-MLP plasmid DNA (25 ng) was preincubated with
40 ng of FLAG-tagged Gal4-VP16 in EX-20 buffer plus 0.5 mg of bovine
serum albumin (BSA) per ml for 10 min at room temperature. The
acetylation step was performed with 5 µl of M2-purified STAGA or the
M2 mock-purified fraction for 30 min at 30°C in transcription buffer
(10 mM Tris-HCl, 20 mM HEPES [pH 7.9], 60 mM KCl, 0.25 mg of BSA per
ml, 6 mM MgCl2, 5 mM DTT, 30 mM ATP, 10 mM
phosphocreatine, 0.5 µg of creatine phosphokinase, 12% glycerol, 10 U of RNasin) with or without 1 µM acetyl-CoA. Then HeLa nuclear
proteins (35 µg) were added, and reaction mixtures were incubated for
30 min at 30°C. Transcription was initiated by addition of 0.5 mM
UTP, 0.5 mM ATP, 12.5 µM CTP, 10 µCi
[32P]CTP, and 0.1 mM
3'-O-methyl-GTP. After a 40-min incubation at 30°C,
reactions were stopped by addition of 10 mM EDTA. Following a 20-min
treatment at 37°C with 20 U of RNase T1 (Boehringer Mannheim), purified transcripts were analyzed on 7 M urea-8% polyacrylamide gels. Quantitation was performed on a PhosphorImager (Molecular Dynamics).
EMSA.
For electrophoretic mobility shift assays (EMSA), the
probe was a 239-bp HindIII DNA fragment from plasmid
pG5T+I+ that had been
labeled with Klenow enzyme and [32P]dCTP and
either mock irradiated or UV irradiated at 254 nm using a
UV-Stratalinker (Stratagene) at 5,000 or 15,000 J/m2. The binding reactions were performed at
25°C for 30 min with 0.1 ng of labeled probe and 4 to 5 µl of
M2-purified STAGA or mock control fraction in a final volume of 8 to 10 µl containing 10 mM Tris-HCl (pH 7.9), 20 mM HEPES (pH 7.9), 10%
glycerol, 50 mM KCl, 15 mM NaCl, 4 mM MgCl2, 5 mM
DTT, 4 µg of BSA, 0.025% NP-40, 0.25 mM EDTA, 20 ng of
poly[d(I-C)], and unlabeled UV-irradiated or mock-irradiated
competitor DNA. For antibody supershift assays, STAGA was
preincubated with 0.5 µl of diluted antisera (1:20 dilution in BC100
plus 0.5 mg of BSA per ml) for 15 min on ice before addition to binding
reactions. Binding reactions were analyzed on 5% PAGE gels in TGE
buffer (25 mM Tris-HCl, 190 mM glycine, 1 mM EDTA [pH 8.3]).
Affinity purification of the human STAGA complex.
To further
characterize the human STAGA complex, HeLa cell lines that stably
express ectopic fh:SPT3 and fh:TAFII31 were
established. Anti-FLAG immunoaffinity chromatography was used to purify
epitope-tagged STAGA from nuclear extracts of fh:SPT3-expressing cells.
Purified STAGA contained, besides fh:SPT3 (identified by immunoblotting and MS), at least 17 additional SPT3-associated factors (STAFs) (Fig.
1A, lane 2) that were absent in the
mock-purified fraction derived from nuclear extracts of control
(untransfected) HeLa cells (lane 1). Furthermore, STAFs remained
specifically associated with fh:SPT3 after a subsequent purification on
an anti-HA immunoaffinity resin (lane3) and coimmunopurified with
untagged hSPT3 from nuclear extracts of
fh:TAFII31-expressing cells (see below; see Fig.
3). Most STAFs also copurified during ion-exchange and protein-affinity chromatography and cosedimented in a glycerol gradient (see below; see
Fig. 5 and 6; also data not shown). These data indicate that hSPT3 is
in a large multiprotein complex with TAFII31 and
other STAFs.
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.20.6782-6795.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Human STAGA Complex Is a
Chromatin-Acetylating Transcription Coactivator That Interacts with
Pre-mRNA Splicing and DNA Damage-Binding Factors In Vivo



![]()
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
![]()
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
![]()
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
(PAF65
),
VHVSYLDGK, VALQDLQTNSK,
KLTVEDFNR, AVLGDDPQLMK, KMPQLTASAIVSPHGDESPR, LFQTAFPAPYGPSPASR,
ELYAFFGDSLATR, and
GNLAPQGSVPSAVSSLTDDLLK; for STAF65
(PAF65
),
GPVLSLAFSPNGK and LWDLASGTLYK; for
STAF65
(KIAA0764), YWGEIPISSSQTNR; for STAF54
(hADA3), VLEAETQILTDWQDK; for STAF42,
KNLSEALGDNVK, YAFGSNVTPQPYLK,
ISKEEFDLEAHR, EVIPTHTVYALNIER, and
DILTSVVSR; for STAF31/32
(TAFII31), DMGITEYEPR,
PSTPTLGTPTPQTMSVSTK, FTVQMPTSQSPAVK,
DAQMMAQILK, DFLLDIAR, VINQMLEFAFR,
and ASIPATSAVQNVLINPSLIGSK; for STAF28
(TAFII30), ASPAGTAGGPGAGAAAGGTGPLAAR
and YTLTMEDLTPALSEYGINVK; and for STAF20/15
(TAFII20/15), LSPENNQVLTK and DVQLHLER.
![]()
RESULTS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References

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FIG. 1.
Affinity purification and composition of the human STAGA
complex. (A) Immunopurified STAGA complex. Shown is a silver stain of
gradient SDS-PAGE gels containing STAGA purified from nuclear extracts
of the fh:SPT3-expressing cell line (lanes 2 and 3) and mock-purified
fractions derived from control HeLa nuclear extracts (lanes 1 and 4)
after affinity purification on M2-agarose (lanes 1 and 2) or after
successive immunopurifications M2-agarose and anti-HA antibody resins
(lanes 3 and 4). The positions of fh:SPT3 and STAFs with their
approximate molecular masses are indicated. (B) Identity of STAFs
determined by tandem MS. n.a., not analyzed.
Identification of STAGA components. Identification of most STAFs was performed by MS and by searching the NCBI nonredundant and dBEST databases with the mass spectral data (see Materials and Methods). The results are summarized in Fig. 1B and described in more detail below. The complete list of peptide sequences can be found in Materials and Methods. The identity of most STAGA components was further verified by immunoblot analyses using specific antibodies (see below).
STAGA contains the transcription-transformation cofactor TRRAP, hGCN5L acetylase, novel human ADA-like and SPT-like cofactors, and a subset of TAFIIs. The STAF400 protein band yielded six distinct peptide sequences corresponding to the TRRAP protein. TRRAP is an ATM-related protein that was originally identified through its interaction with the c-Myc and E2F1 transcription activation domains and that has been implicated in c-Myc-mediated oncogenic transformation in vitro (47). TRRAP is also present in human PCAF complex, TFTC, and TIP60 HAT complexes (8, 35, 73), and a yeast homolog, Tra1, is a subunit of the SAGA and NuA4 HAT complexes (3, 26, 59).
The STAF97 band yielded four peptide sequences belonging to hGCN5L. Two (TLPENLTLEDAK and SHPSAWPFMEPVK) are specific for hGCN5L. This is consistent with previous demonstrations that PCAF is either present in very small amounts or absent in HeLa cells (45, 62, 79). The clustered STAF65 protein bands correspond to three distinct proteins (STAF65
, -
, and -
). STAF65
(eight peptide
sequences) and STAF65
(two peptide sequences) are, respectively, the
PAF65
and PAF65
subunits originally found in the human PCAF
complex. PAF65
and PAF65
share significant sequence similarities,
respectively, with human TAFII80 and
TAFII100, suggesting similar functions (53). Consistent with this, the yeast SAGA complex lacks
PAF65 homologs but instead contains yeast TAFII60
and TAFII90, the bona fide homologs of human
TAFII80 and TAFII100, respectively.
STAF65
was identified by the peptide sequence YWGEIPISSSQTNR and
is encoded by a gene (KIAA0764) of unknown function. BLAST searches of
the NCBI protein databases revealed similarities with the yeast SAGA
subunit SPT7. Alignment of both proteins using a MacVector program
indicated that STAF65
is similar (20% identity and 38% similarity)
over its entire length to the yeast SPT7 C terminus, which includes a
histone fold domain (Fig.
2A). This might suggest
a function for STAF65
within the STAGA complex comparable to the
role of yeast SPT7 in maintaining the integrity of the SAGA complex
(22, 25).
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Specific in vivo association of STAGA with a pre-mRNA splicing factor. A total of 21 different tryptic peptide sequences identified STAF130 as the recently characterized SAP130. The specific association of SAP130 with highly purified STAGA was confirmed by Western blot analyses (Fig. 3C). SAP130 coimmunopurified with other STAFs under stringent conditions (300 mM KCl, 0.05% NP-40) on M2-agarose only from nuclear extracts of fh:SPT3-expressing cells (lane 1) and not from control HeLa nuclear extracts (lane 2). SAP130 is a component of the splicing factor complex SF3b, a submodule of the 17S U2 snRNP particle (17). Interestingly, significant amounts of STAF130 (SAP130) were associated with STAGA after two successive immunopurification steps (Fig. 1A, lane 3) at salt concentrations (300 to 400 mM KCl) that are known to disrupt SF3b association with U2 snRNP (6). Under these conditions, none of the STAFs that have been analyzed contained peptides belonging to other SF3b-U2 snRNP subunits. Moreover, significant amounts of SAP130 in the nuclear extract were also specifically coimmunoprecipitated with fh:SPT3 under more physiological salt concentrations (100 to 150 mM KCl) that are known to preserve the association of SF3b with the U2 snRNP particle (see Fig. 7C). SAP130 did not merely interact with overexpressed free fh:SPT3 but was preferentially associated with fh:SPT3-STAF complexes. Indeed, S-Sepharose fractionation of immunopurified STAGA separated free fh:SPT3 (found in the column flowthrough) from bound fractions that contained SPT3-STAF complexes and most of SAP130 (Fig. 6C). However, small amounts of SAP130 were also detected in the flowthrough fraction and STAGA-s could also be isolated (see below; see Fig. 5A and Fig. 6C). Furthermore, immunoblot analyses demonstrated that SAP130 also coimmunoprecipitated with fh:TAFII31 (data not shown). Altogether, these data demonstrate an interaction of SAP130 with STAGA in vivo and suggest that SAP130 might not be as tightly associated with STAGA as the other STAF subunits.
STAGA is an acetyl-CoA-dependent transcription coactivator on a chromatin-assembled template in vitro. The existence of at least three different human SAGA-like complexes (i.e., PCAF complex, TFTC, and STAGA), and the fact that splicing factors have so far not been described in association with any other coactivator and/or HAT complex, raised the question of whether STAGA is involved in transcription regulation in a manner similar to that of the yeast SAGA complex or whether it is a specialized human complex dedicated to other RNA, DNA, or chromatin transactions.
We originally addressed a possible transcription function of STAGA by using various nonchromatinized (naked) DNA templates and either crude nuclear extracts immunodepleted of both TFIID and STAGA or systems reconstituted with purified general transcription factors and RNA polymerase II. In all cases we were unable to observe STAGA-dependent transcription in the absence of TFIID or TBP (data not shown). This further differentiates STAGA from TFTC, which was shown previously to have TFIID-like functions (77). Furthermore, STAGA neither influenced basal transcription nor potentiated activator (Gal4-VP16)-dependent transcription in crude nuclear extracts and in PC4-dependent purified systems containing either TFIID or TBP; moreover, addition of acetyl-CoA had no effect in these systems (data not shown; also see below). We then investigated whether STAGA might function primarily at the chromatin level. In agreement with previous observations (46) purified STAGA preferentially acetylated histone H3 in equimolar mixtures of all four free core histones (Fig. 4A, lane 1). Moreover, immunopurified STAGA (Fig. 4, lane 3), but not the control mock-purified fraction (lane 2), also acetylated predominantly H3 within nucleosomes, albeit with a lower efficiency (compare lanes 1 and 3). To test for a possible transcription function of STAGA on chromatin in vitro, a plasmid DNA containing five Gal4-binding sites upstream of the adenovirus major late core promoter and a G-less cassette (G5-MLP) was assembled into nucleosome arrays by using a Drosophila embryo S190 assembly extract complemented with purified HeLa core histones. The nucleosomal G5-MLP template ("crude chromatin") was either used directly in transcription reactions or further purified by gel filtration. This step removes S190 factors (including HATs, acetyl-CoA, and ATP) that are present in the assembly reaction but does not completely remove ATP-dependent chromatin remodeling activities (19) (see below). Agarose gel analysis of the purified G5-MLP chromatin template digested with micrococcal nuclease indicated a circa-180-bp regular DNA ladder, which confirmed the assembly of 19 physiologically spaced nucleosomes on the G5-MLP plasmid (Fig. 4B).
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STAGA interacts in vivo and in vitro with
UV-damaged-DNA-binding proteins.
The STAGA-associated
protein SAP130 belongs to a family of structurally related
proteins that include the 160-kDa cleavage and polyadenylation
specificity factor (CPSF160) and the UV-damaged-DNA-binding protein DDB1 (13, 17, 48). In fact, SAP130 is more closely related in amino acid sequence to DDB1 (22% identity) than to CPSF160
(47) (data not shown). The 127-kDa DDB1 and the
48-kDa DDB2 proteins interact to constitute the active
UV-damaged-DNA-binding factor UV-DDB (reviewed in reference
66). The striking structural similarity between SAP130 and
DDB1 suggested the possibility of common interacting target factors
and/or a function of SAP130 in recognition of UV-damaged DNA. Thus, we
tested for UV-damaged-DNA-binding activity in purified STAGA. By EMSA
we detected a UV dose-dependent DNA-binding activity that was
specifically associated with immunopurified STAGA, compared with the M2
mock-purified fraction (Fig. 6A, lanes 1 to 3 versus 4 to 6). This activity was competed
specifically with DNA that had been UV irradiated (Fig. 6B, lane 3) but
not with nonirradiated DNA (lane 4). The same results were obtained by
using unrelated DNA probes, indicating that the binding is independent
of DNA sequence and length (data not shown).
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DISCUSSION |
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This report presents the purification, structural characterization, and functional analysis of the human STAGA complex. We demonstrate that STAGA is a coactivator complex that potentiates, in an acetyl-CoA-dependent manner, activator-dependent transcription in vitro on chromatin templates. Furthermore, we show specific interactions of STAGA with pre-mRNA splicing and UV-damaged-DNA recognition and repair factors in vivo. These results provide the first evidence for a direct association of a component of the general splicing machinery with a transcription coactivator complex and suggest additional roles of STAGA in nucleosomal histone acetylation during DNA damage recognition and/or repair of chromatin in vivo.
Structural relationships of human STAGA to yeast SAGA, other human
SAGA-like complexes, and TFIID.
The subunit composition of STAGA
reveals a striking complexity and structural resemblance to the yeast
SAGA and the human PCAF and TFTC complexes. STAGA appears to be more
closely related to the PCAF complex than to the TFTC complex. Indeed,
besides their different HATs (hGCN5L versus PCAF), STAGA and PCAF
complexes share many subunits that include hSPT3, hADA2, hADA3,
PAF65
, PAF65
, TAFII31,
TAFII30, TAFII20/15, and
TRRAP. Only a subset of these (hGCN5L, hSPT3, hADA3, PAF65
,
TAFII31, TAFII30,
TAFII20/15, and TRRAP) were also found in the
human TFTC complex. Moreover, both STAGA and PCAF complexes lack
high-molecular-weight TAFIIs (i.e.,
TAFII55, TAFII80,
TAFII100, TAFII135, and
TAFII150) that are uniquely shared by TFTC and
TFIID (8). Consistent with this, and in contrast to the
TFIID-like function of the TFTC complex (77), STAGA could
not substitute for TFIID in our in vitro transcription assays.
, which is encoded by the
KIAA0764 gene of previously unknown function, and STAF42, a novel
histone H2A-like protein. STAF65
and STAF42 have significant similarity, respectively, to SPT7 and ADA1 components of the yeast SAGA
complex. Thus, our results show that all yeast SAGA subunits described
so far, with the notable exception of SPT8 and SPT20 (ADA5), have human
counterparts within STAGA, suggesting that human STAGA is a bona fide
functional homolog of yeast SAGA (see also below). Note that it remains
possible that homologs of yeast SPT8 and SPT20 are among the few STAF
proteins that were not analyzed by MS.
The 130-kDa STAGA-associated factor was identified as SAP130 (see
below). The corresponding yeast homolog (Rse1p) has not yet been
reported to interact with yeast SAGA, which could point to a
potentially significant difference between human and yeast cells.
Alternatively, by analogy to the relatively loose association of SAP130
with human STAGA, Rse1p might also dissociate during the multiple
chromatographic steps required to purify the native SAGA complex.
The relatedness of STAF42 to histone H2A and
TAFII135 also suggests the presence of a histone
octamer-like structure within STAGA similar to that proposed for TFIID
and yeast SAGA (reviewed in references 22 and
23). Moreover, the structural resemblance between STAGA
and TFIID further extends to their association with the structurally
related pre-mRNA processing factors SAP130 and CPSF160 and might also
indicate a conservation at the functional level (see below).
Transcription coactivator functions of STAGA on chromatin. In accord with the structural similarities of human STAGA to the yeast SAGA coactivator complex, we also have shown that the STAGA complex can be recruited by an acidic activation domain (VP16), acetylates predominantly histone H3 within nucleosomes, and exhibits acetyl-CoA-dependent coactivator functions on chromatin templates in vitro (Fig. 4 and 5). Thus, in a manner similar to that of yeast SAGA (34, 72), STAGA recruitment by activators might target its nucleosomal acetylation functions to the promoter. The fact that under our conditions STAGA and acetyl-CoA do not influence promoter activity on naked DNA templates, either in nuclear extracts or in purified transcription systems (Fig. 4D and data not shown), is consistent with a selective requirement of the STAGA HAT activity in nucleosome acetylation. Our in vitro results, however, do not exclude additional roles of STAGA in facilitating or stabilizing activator-chromatin interactions or the possibility that STAGA might also acetylate other nonhistone proteins and/or function as an adapter to help recruit the basal transcription machinery. Consistent with this possibility, several yeast SAGA components have been shown to interact with TBP (TAFIIs, SPT3, and SPT8) and acidic activators (ADAs). Furthermore, the largest STAGA subunit, TRRAP, is a protein that interacts with c-Myc and E2F1 transcription activation domains (47).
Interestingly, the VP16 activation domain recruits preferentially STAGA and components of the TRAP (SMCC) coactivator complex from nuclear extracts relative to components of the general transcription machinery (TBP, TFIIB, and TFIIH) and TFIID- and TFTC-specific TAFIIs (Fig. 5B). This contrasts (but is not incompatible) with earlier observations and models identifying direct interactions of activators with TFIID or TBP, TFIIB, and/or TFIIH as critical steps in activation (reviewed in reference 56). Our observation, however, correlates with (i) the fact that TFIID-specific TAFIIs are not generally required for activation in yeast (50, 75), (ii) the recent demonstration that transcription activation by Gal4-VP16 in crude HeLa nuclear extracts does not require TFIID-specific TAFIIs but depends on human SRB7 (53), a component of the TRAP (SMCC) complex (reviewed in reference 45), and (iii) the dependence on yeast SRB4 (a component of the yeast SRB/Mediator complex) for TBP recruitment to promoters that do not require TFIID-specific TAFIIs in vivo (43). The preferential recruitment of STAGA from nuclear extracts by the VP16 activation domain might also suggest a function of STAGA early during the activation process (e.g., in chromatin modification). This would be consistent with the observed ordered recruitment of hGCN5 and general transcription factors to the beta interferon promoter (2) and the requirement in vitro and in certain cases in yeast cells for activator-dependent nucleosome acetylation by GCN5 or SAGA prior to ATP-dependent chromatin remodeling at the promoter by the SWI-SNF complex (28, 58). However, a possible additional role of STAGA or SAGA at later stages cannot be excluded (see above).STAGA links coactivators to a component of the splicing machinery. A surprising but significant finding is the identification of the spliceosome-associated protein SAP130 as a STAGA-associated factor in vivo. Human SAP130 is a component of the splicing factor SF3b, a U2 snRNP-associated protein complex that is essential for spliceosome assembly (17) and is enriched in nuclear interchromatin granule clusters, or "speckles" (49). Both SF3b and SF3a complexes associate with the 12S U2 snRNP to form the functional 17S U2 snRNP particle that ultimately stably interacts, in an ATP-dependent manner, with the intronic pre-mRNA branch point site. The precise function of SAP130 is unknown. The fact that SAP130 is the only subunit within SF3b that cannot be UV cross-linked to pre-mRNA in the prespliceosome complex suggests a non-RNA-binding function (reviewed in references 13, 17, and 40). The yeast homolog of SAP130, Rse1p, is essential both for spliceosome assembly in vitro and efficient pre-mRNA splicing in vivo (13). Intriguingly, while significant amounts of SAP130 were found to be associated with highly purified STAGA (Fig. 1A, lane 3), other components of SF3b or U2 snRNP were not detected. However, SAP130 is not as stably associated with STAGA as the other bona fide STAF subunits.
What could be the role of SAP130 interaction with STAGA? One possibility is that SAP130, in association with STAGA, has a novel function unrelated to splicing. Alternatively, SAP130 might function as an adapter to link STAGA and transcription regulators to the general splicing machinery. Indeed, pre-mRNA processing events can occur cotranscriptionally through physical interactions of capping, splicing, and 3'-end processing factors with the hyperphosphorylated C-terminal domain of the large subunit of RNA polymerase II (reviewed in reference 31). Moreover, a promoter-directed "C-terminal-domain-loading" mechanism might exist to recruit pre-mRNA processing factors during the early transcription initiation and elongation phase, an idea supported by the TFIID-mediated recruitment of CPSF to the elongating RNA polymerase II (16). The structural similarities between TFIID and STAGA complexes and between their respective associated factors, CPSF160 and SAP130, thus suggest a possible function for STAGA-SAP130 interactions in the recruitment of the general splicing machinery to actively transcribed genes. This is in accord with the recruitment of SAP130 and STAGA components in nuclear extracts by the VP16 transcription activation domain (Fig. 5) and is consistent with the recent finding that U2 snRNP is incorporated early into the prespliceosomal E complex in an ATP-independent manner (18). A role of transcription factors and associated cofactors in the regulation of pre-mRNA splicing is also supported by evidence of promoter-dependent alternative splicing in vivo (15). Moreover, immunofluorescence studies showing a preferential localization of highly acetylated histone H3-containing chromatin at the periphery of interchromatin granule clusters also suggest a possible functional colocalization of STAGA and/or other H3-acetylating HATs with sites of active cotranscriptional splicing in the nucleus (30).Interaction of STAGA with UV-DDB and XPE factors involved in DNA damage repair and the hereditary disease xeroderma pigmentosum. We have shown that STAGA associates in HeLa cells with DDB1 and DDB2 components of the UV-damaged-DNA-binding factor UV-DDB. UV-DDB recognizes various DNA-distorting lesions, including those induced by UV irradiation and certain anticancer drugs and has been implicated in global genomic nucleotide excision repair (NER) in vivo, a pathway that includes the repair of the nontranscribed strand of expressed genes (reviewed in references 38 and 66). Missense mutations in the DDB2 gene and the absence of UV-DDB activity are associated with deficient NER in a subset of individuals with the autosomal recessive disease xeroderma pigmentosum of group E (XPE), which is characterized by UV sensitivity and a high incidence of skin cancer (reference 51 and references therein). However, UV-DDB is not required for transcription-coupled NER of transcribed strands in vivo and is not required in vitro for NER in systems reconstituted with purified factors (1). This has led to the suggestion that UV-DDB might be specifically required in vivo for global genomic NER within chromatin (32, 55, 66), a notion that is consistent with the inhibition of NER by nucleosomes (reviewed in references 48 and 68). Significantly, additional roles for UV-DDB have also been proposed, including a function as a transcription partner for E2F1 (29).
The in vivo and in vitro interactions of STAGA with UV-DDB presented here support a role of UV-DDB in DNA repair within chromatin and further suggest possible mechanisms. In a manner analogous to SAGA and STAGA recruitment by promoter-bound activators, the interaction of UV-DDB with STAGA might target the nucleosome acetylase activity of GCN5L to damaged chromatin sites in order to facilitate the assembly and/or function of the NER machinery on nucleosomes. As for transcription activation, a highly stable interaction of STAGA with DDB1 might not be necessary; indeed, only a transient acetylation by SAGA is sufficient to mark nucleosomes for subsequent remodeling by the SWI-SNF complex at the yeast PHO8 promoter in vivo (58). This also would be consistent with the observed enhanced DNA repair synthesis of hyperacetylated nucleosomes in vivo (57) and the facilitation of NER on synthetic dinucleosomes by the ATP-dependent chromatin remodeling factor ACF (71). In an alternative (but not mutually exclusive) model, STAGA might preferentially recruit UV-DDB and the basal repair machinery to active genes through acetylation-mediated chromatin unfolding and/or through direct physical recruitment of UV-DDB to the damaged sites. This possibility is consistent with a role of STAGA as a transcription coactivator on chromatin and with previously observed interactions of UV-DDB with viral and cellular transcription activators (29, 42, 44). In addition, this model might also provide a rationale for the observed efficient repair of nontranscribed promoter and coding sequences in certain genes (references 67, 69, and 70 and references therein) and the surprisingly efficient repair of the nontranscribed strands of active genes in differentiated cells that have an otherwise very inefficient global genomic repair (reviewed in reference 52). In any case, our results suggest a possible role of STAGA in NER within chromatin that parallels recent reports linking components of the human TIP60 HAT complex and the yeast INO80 ATP-dependent chromatin remodeling complex to the repair of DNA breaks in vivo (35, 60). In conclusion, we have identified novel histone fold-containing proteins as subunits of the human STAGA complex and shown that STAGA is a transcription coactivator-HAT complex and a bona fide human homolog of the yeast SAGA complex. The intriguing previous observation that DDB1 belongs to a family of structurally related proteins that include CPSF160 and the splicing factor SAP130 raised the possibility of common and/or related roles and interacting factors for these apparently functionally distinct proteins (13, 17). Our results support this notion by the identification of STAGA as a common interacting partner for DDB1 and SAP130, while CPSF160 might preferentially associate with the related TFIID complex (16). These observations further suggest possible additional functions of STAGA in splicing and DNA repair of chromatin, two processes that are coupled to transcription in vivo.| |
ACKNOWLEDGMENTS |
|---|
We thank G. Chu for pBJ5-FLAG-p125/DDB1, S. Berger for hADA2 antiserum, J. Manley for CPSF160 antibodies, R. Lamb for pGEX-5X-3-DDB1, S. Linn for p48 (DDB2) antibodies, S. McMahon and M. Cole for TRRAP antiserum, B. Slagle for XAP1 (DDB1) peptide antibodies, A. Krutchinsky for valuable contributions, and J. Fu and C. Bhattacharyya for technical assistance. We are also grateful to Cedric S. Wesley for the help in establishment of the large population of Drosophila flies.
This work was supported by grants from the NIH to R.G.R. (CA42567) and B.T.C. (RR00862).
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ADDENDUM |
|---|
Similar to the results reported here for STAGA, studies published while this article was under review have shown that TFTC is recruited to UV-damaged DNA (9) and that the PCAF complex facilitates transcription of chromatin in vitro (49a).
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FOOTNOTES |
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* Corresponding author. Mailing address: Laboratories of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Ave., New York, NY 10021. Phone: (212) 327-7600. Fax: (212) 327-7949. E-mail: roeder{at}mail.rockefeller.edu.
Present address: Department of Biochemistry, University of
California, Riverside, CA 92521.
Present address: Biovitrum AB, SE-11276, Stockholm, Sweden.
§ Present address: Biology Department, Brookhaven National Laboratory, Upton, NY 11973.
Present address: Transcription and Disease Laboratory, Jawaharlal
Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
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REFERENCES |
|---|
|
|
|---|
| 1. | Aboussekhra, A., M. Biggerstaff, M. K. Shivji, J. A. Vilpo, V. Moncollin, V. N. Podust, M. Protic, U. Hubscher, J. M. Egly, and R. D. Wood. 1995. Mammalian DNA nucleotide excision repair reconstituted with purified protein components. Cell 80:859-868[CrossRef][Medline]. |
| 2. |
Agalioti, T.,
S. Lomvardas,
B. Parekh,
J. Yie,
T. Maniatis, and D. Thanos.
2000.
Ordered recruitment of chromatin modifying and general transcription factors to the IFN- promoter.
Cell
103:667-678[CrossRef][Medline].
|
| 3. | Allard, S., R. T. Utley, J. Savard, A. Clarke, P. A. Grant, C. J. Brandl, L. Pillus, J. L. Workman, and J. Côté. 1999. NuA4, an essential transcription adaptor/histone H4 acetyltransferase complex containing Esa1p and the ATM-related cofactor Tra1p. EMBO J. 18:5108-5119[CrossRef][Medline]. |
| 4. | Ayer, D. E. 1999. Histone deacetylases: transcriptional repression with SINers and NuRDs. Trends Cell. Biol. 9:193-198[CrossRef][Medline]. |
| 5. | Becker, P. B., T. Tsukiyama, and C. Wu. 1994. Chromatin assembly extracts from Drosophila embryos. Methods Cell Biol. 44:207-223[Medline]. |
| 6. |
Behrens, S.-E.,
K. Tyc,
B. Kastner,
J. Reichelt, and R. Lührmann.
1993.
Small nuclear ribonucleoprotein (RNP) U2 contains numerous additional proteins and has a bipartite RNP structure under splicing conditions.
Mol. Cell. Biol.
13:307-319 |
| 7. | Bradbury, E. M. 1992. Reversible histone modifications and the chromosome cell cycle. BioEssays 14:9-16[CrossRef][Medline]. |
| 8. |
Brand, M.,
K. Yamamoto,
A. Staub, and L. Tora.
1999.
Identification of TATA-binding protein-free TAFII-containing complex subunits suggests a role in nucleosome acetylation and signal transduction.
J. Biol. Chem.
274:18285-18289 |
| 9. | Brand, M., J. G. Moggs, O.-A. Mustapha, L. Fabrice, F. J. Dilworth, J. Stevenin, G. Almouzni, and L. Tora. 2001. UV-damaged DNA-binding protein in TFTC complex links DNA damage recognition to nucleosome acetylation. EMBO J. 20:3187-3196[CrossRef][Medline]. |
| 10. | Brown, C. E., T. Lechner, L. Howe, and J. L. Workman. 2000. The many HATs of transcription coactivators. Trends Biol. Sci. 25:15-19. |
| 11. | Bulger, M., and J. T. Kadonaga. 1994. Biochemical reconstitution of chromatin with physiological nucleosome spacing. Methods Mol. Genet. 5:241-262. |
| 12. | Candau, R., P. A. Moore, L. Wang, N. Barlev, C. Y. Ying, C. A. Rosen, and S. L. Berger. 1996. Identification of human proteins functionally conserved with the yeast putative adaptors ADA2 and GCN5. Mol. Cell. Biol. 16:593-602[Abstract]. |
| 13. | Caspary, F., A. Shevchenko, M. Wilm, and B. Séraphin. 1999. Partial purification of the yeast U2 snRNP reveals a novel yeast pre-mRNA splicing factor required for pre-spliceosome assembly. EMBO J. 18:3463-3474[CrossRef][Medline]. |
| 14. | Côté, J., T. Utley, and J. L. Workman. 1995. Basic analysis of transcription factor binding to nucleosomes. Methods Mol. Genet. 6:108-152[CrossRef]. |
| 15. | Cramer, P., J. F. Cáceres, D. Cazalla, S. Kadener, A. F. Muro, F. E. Baralle, and A. R. Kornblihtt. 1999. Coupling of transcription with alternative splicing: RNA pol II promoters modulate SF2/ASF and 9G8 effects on an exonic splicing enhancer. Mol. Cell 4:251-258[CrossRef][Medline]. |
| 16. | Dantonel, J.-C., K. G. K. Murthy, J. L. Manley, and L. Tora. 1997. Transcription factor TFIID recruits factor CPSF for formation of 3' end of mRNA. Nature 389:399-402[CrossRef][Medline]. |
| 17. |
Das, B. K.,
L. Xia,
L. Paladjian,
O. Gozani,
Y. Chyung, and R. Reed.
1999.
Characterization of a protein complex containing spliceosomal proteins SAPs 49, 130, 145, and 155.
Mol. Cell. Biol.
19:6796-6802 |
| 18. | Das, R., Z. Zhou, and R. Reed. 2000. Functional association of U2 snRNP with the ATP-independent spliceosomal complex E. Mol. Cell 5:779-787[CrossRef][Medline]. |
| 19. | Dilworth, F. J., C. Fromental-Ramain, K. Yamamoto, and P. Chambon. 2000. ATP-driven chromatin remodeling activity and histone acetyltransferases act sequentially during transactivation by RAR/RXR in vitro. Mol. Cell 6:1049-1058[CrossRef][Medline]. |
| 20. |
Eberharter, A.,
D. E. Sterner,
D. Schieltz,
A. Hassan,
J. R. Yates III,
S. L. Berger, and J. L. Workman.
1999.
The ADA complex is a distinct histone acetyltransferase complex in Saccharomyces cerevisiae.
Mol. Cell. Biol.
19:6621-6631 |
| 21. |
Fujiwara, Y.,
C. Masutani,
T. Mizukoshi,
J. Kondo,
F. Hanaoka, and S. Iwai.
1999.
Characterization of DNA recognition by the human UV-damaged DNA-binding protein.
J. Biol. Chem.
274:20027-20033 |
| 22. |
Gangloff, Y.-G.,
S. L. Sanders,
C. Romier,
D. Kirschner,
P. A. Weil,
L. Tora, and I. Davidson.
2001.
Histone folds mediate selective heterodimerization of yeast TAFII25 with TFIID components yTAFII47 and yTAFII65 and with SAGA component ySPT7.
Mol. Cell. Biol.
21:1841-1853 |
| 23. |
Gangloff, Y.-G.,
S. Werten,
C. Romier,
L. Carré,
O. Poch,
D. Moras, and I. Davidson.
2000.
The human TFIID components TAFII135 and TAFII20 and yeast SAGA components ADA1 and TAFII68 heterodimerize to form histone-like pairs.
Mol. Cell. Biol.
20:340-351 |
| 24. | Grant, P. A., and S. L. Berger. 1999. Histone acetyltransferase complexes. Semin. Cell Dev. Biol. 10:169-177[CrossRef][Medline]. |
| 25. |
Grant, P. A.,
L. Duggan,
J. Côté,
S. M. Roberts,
J. E. Brownell,
R. Candau,
R. Ohba,
T. Owen-Hughes,
C. D. Allis,
F. Winston,
S. L. Berger, and J. L. Workman.
1997.
Yeast Gcn5 functions in two multisubunit complexes to acetylate nucleosomal histones: characterization of an Ada complex and the SAGA (Spt/Ada) complex.
Genes Dev.
11:1640-1650 |
| 26. | Grant, P. A., D. Schieltz, M. G. Pray-Grant, J. R. Yates III, and J. L. Workman. 1998. The ATM-related cofactor Tra1 is a component of the purified SAGA complex. Mol. Cell 2:863-867[CrossRef][Medline]. |
| 27. | Gu, W., and R. G. Roeder. 1997. Activation of p53 sequence-specific DNA binding by acetylation of the p53 C-terminal domain. Cell 90:595-606[CrossRef][Medline]. |
| 28. | Hassan, A. H., K. E. Neely, and J. L. Workman. 2001. Histone acetyltransferase complexes stabilize SWI/SNF binding to promoter nucleosomes. Cell 104:817-827[CrossRef][Medline]. |
| 29. |
Hayes, S.,
P. Shiyanov,
X. Chen, and P. Raychadhuri.
1998.
DDB, a putative DNA repair protein, can function as a transcriptional partner of E2F1.
Mol. Cell. Biol.
18:240-249 |
| 30. |
Hendzel, M. J.,
M. J. Kruhlak, and D. P. Bazett-Jones.
1998.
Organization of highly acetylated chromatin around sites of heterogeneous nuclear RNA accumulation.
Mol. Biol. Cell
9:2491-2507 |
| 31. |
Hirose, Y., and J. L. Manley.
2000.
RNA polymerase II and the integration of nuclear events.
Genes Dev.
14:1415-1429 |
| 32. |
Hwang, B. J.,
J. M. Ford,
P. C. Hanawalt, and G. Chu.
1999.
Expression of the p48 xeroderma pigmentosum gene is p53-dependent and is involved in global genomic repair.
Proc. Natl. Acad. Sci. USA
96:424-428 |
| 33. |
Hwang, B. J.,
S. Toering,
U. Francke, and G. Chu.
1998.
p48 activates a UV-damaged-DNA binding factor and is defective in xeroderma pigmentosum group E cells that lack binding activity.
Mol. Cell. Biol.
18:4391-4399 |
| 34. |
Ikeda, K.,
D. J. Steger,
A. Eberharter, and J. L. Workman.
1999.
Activation domain-specific and general transcription stimulation by native histone acetyltransferase complexes.
Mol. Cell. Biol.
19:855-863 |
| 35. | Ikura, T., V. V. Ogryzko, M. Grigoriev, R. Groisman, J. Wang, M. Horikoshi, R. Scully, J. Qin, and Y. Nakatani. 2000. Involvement of the TIP60 histone acetylase complex in DNA repair and apoptosis. Cell 102:463-473[CrossRef][Medline]. |
| 36. | Ito, M., C. X. Yuan, S. Malik, W. Gu, J. D. Fondell, S. Yamamura, Z. Y. Fu, X. Zhang, J. Qin, and R. G. Roeder. 1999. Identity between TRAP and SMCC complexes indicates novel pathways for the function of nuclear receptors and diverse mammalian activators. Mol. Cell 3:361-370[CrossRef][Medline]. |
| 37. |
Kamakaka, R. T.,
M. Bulger, and J. T. Kadonaga.
1993.
Potentiation of RNA polymerase II transcription by Gal4-VP16 during but not after DNA replication and chromatin assembly.
Genes Dev.
7:1779-1795 |
| 38. |
Keeney, S.,
A. P. M. Eker,
T. Brody,
W. Vermeulen,
D. Bootsma,
J. H. J. Hoeijmakers, and S. Linn.
1994.
Correction of the DNA repair defect in xeroderma pigmentosum group E by injection of a DNA damage-binding protein.
Proc. Natl. Acad. Sci. USA
91:4053-4056 |
| 39. |
Kingston, R. E., and G. J. Narlikar.
1999.
ATP-dependent remodeling and acetylation as regulators of chromatin fluidity.
Genes Dev.
13:2339-2352 |
| 40. |
Krämer, A.,
P. Grüter,
K. Gröning, and B. Kastner.
1999.
Combined biochemical and electron microscopic analyses reveal the architecture of the mammalian U2 snRNP.
J. Cell Biol.
145:1355-1368 |
| 41. | Krutchinsky, A. N., W. Zhang, and B. T. Chait. 2000. Rapidly switchable matrix-assisted laser desorption/ionization and electrospray quadrupole-time-of-flight mass spectrometry for protein identification. J. Am. Soc. Mass Spectrom. 11:493-504[CrossRef][Medline]. |
| 42. | Lee, T.-H., S. J. Elledge, and J. S. Butel. 1995. Hepatitis B virus X protein interacts with a probable cellular DNA repair protein. J. Virology 69:1107-1114[Abstract]. |
| 43. |
Li, X.-Y.,
S. R. Bhaumik, and M. R. Green.
2000.
Distinct classes of yeast promoters revealed by differential TAF recruitment.
Science
288:1242-1244 |
| 44. | Lin, G. Y., R. G. Paterson, C. D. Richardson, and R. A. Lamb. 1998. The V protein of the paramyxovirus SV5 interacts with damage-specific DNA binding protein. Virology 249:189-200[CrossRef][Medline]. |
| 45. | Malik, S., and R. G. Roeder. 2000. Transcriptional regulation through Mediator-like coactivators in yeast and metazoan cells. Trends Biol. Sci. 25:277-283. |
| 46. |
Martinez, E.,
T. K. Kundu,
J. Fu, and R. G. Roeder.
1998.
A human SPT3-TAFII31-GCN5-L acetylase complex distinct from transcription factor IID.
J. Biol. Chem.
273:23781-23785 |
| 47. | McMahon, S. B., H. A. Van Buskirk, K. A. Dugan, T. D. Copeland, and M. D. Cole. 1998. The novel ATM-related protein TRRAP is an essential cofactor for the c-Myc and E2F oncoproteins. Cell 94:363-374[CrossRef][Medline]. |
| 48. | Meijer, M., and M. J. Smerdon. 1999. Accessing DNA damage in chromatin: insights from transcription. BioEssays 21:596-603[CrossRef][Medline]. |
| 49. | Mintz, P. J., S. D. Patterson, A. F. Neuwald, C. S. Spahr, and D. L. Spector. 1999. Purification and biochemical characterization of interchromatin granule clusters. EMBO J. 18:4308-4320[CrossRef][Medline]. |
| 49a. |
Mizuguchi, G.,
A. Vassilev,
T. Tsukiyama,
Y. Nakatani, and C. Wu.
2001.
ATP-dependent nucleosome remodeling and histone hyperacetylation synergistically facilitate transcription of chromatin.
J. Biol. Chem.
276:14773-14783 |
| 50. | Moqtaderi, Z., Y. Bai, D. Poon, P. A. Weil, and K. Struhl. 1996. TBP-associated factors are not generally required for transcription activation in yeast. Nature 383:188-190[CrossRef][Medline]. |
| 51. |
Nichols, A. F.,
T. Itoh,
J. A. Graham,
W. Liu,
M. Yamaizumi, and S. Linn.
2000.
Human damage-specific DNA-binding protein p48. Characterization of XPE mutations and regulation following UV irradiation.
J. Biol. Chem.
275:21422-21428 |
| 52. |
Nouspikel, T., and P. C. Hanawalt.
2000.
Terminally differentiated human neurons repair transcribed genes but display attenuated global DNA repair and modulation of repair gene expression.
Mol. Cell. Biol.
20:1562-1570 |
| 53. | Oelgeschläger, T., Y. Tao, Y. K. Kang, and R. G. Roeder. 1998. Transcription activation via enhanced preinitiation complex assembly in a human cell-free system lacking TAFIIs. Mol. Cell 1:925-931[CrossRef][Medline]. |
| 54. | Ogryzko, V. V., T. Kotani, X. Zhang, R. L. Schiltz, T. Howard, X.-J. Yang, B. H. Howard, J. Qin, and Y. Nakatani. 1998. Histone-like TAFs within the PCAF histone acetylase complex. Cell 94:35-44[CrossRef][Medline]. |
| 55. |
Otrin, V. R.,
I. Kuraoka,
T. Nardo,
M. McLenigan,
A. P. M. Eker,
M. Stefanini,
A. S. Levine, and R. D. Wood.
1998.
Relationship of the xeroderma pigmentosum group E DNA repair defect to the chromatin and DNA binding proteins UV-DDB and replication protein A.
Mol. Cell. Biol.
18:3182-3190 |
| 56. | Ptashne, M., and A. Gann. 1997. Transcriptional activation by recruitment. Nature 386:569-577[CrossRef][Medline]. |
| 57. |
Ramanathan, B., and M. J. Smerdon.
1989.
Enhanced DNA repair synthesis in hyperacetylated nucleosomes.
J. Biol. Chem.
264:11026-11034 |
| 58. | Reinke, H., P. D. Gregory, and W. Hörz. 2001. A transient histone hyperacetylation signal marks nucleosomes for remodeling at the PHO8 promoter in vivo. Mol. Cell 7:529-538[CrossRef][Medline]. |
| 59. |
Saleh, A.,
D. Schieltz,
N. Ting,
S. B. McMahon,
D. W. Litchfield,
J. R. Yates III,
S. P. Lees-Miller,
M. D. Cole, and C. J. Brandl.
1998.
Tra1p is a component of the yeast Ada-Spt transcriptional regulatory complexes.
J. Biol. Chem.
273:26559-26565 |
| 60. | Shen, X., G. Mizuguchi, A. Hamiche, and C. Wu. 2000. A chromatin remodelling complex involved in transcription and DNA processing. Nature 406:541-544[CrossRef][Medline]. |
| 61. | Smerdon, M. J. 1991. DNA repair and the role of chromatin structure. Curr. Opin. Cell Biol. 3:422-428[CrossRef][Medline]. |
| 62. |
Smith, E. R.,
J. M. Belote,
R. L. Schiltz,
X.-J. Yang,
P. A. Moore,
S. L. Berger,
Y. Nakatani, and C. D. Allis.
1998.
Cloning of Drosophila GCN5: conserved features among metazoan GCN5 family members.
Nucleic Acids Res.
26:2948-2954 |
| 63. |
Sterner, D. E.,
P. A. Grant,
S. M. Roberts,
L. J. Duggan,
R. Belotserkovskaya,
L. A. Pacella,
F. Winston,
J. L. Workman, and S. L. Berger.
1999.
Functional organization of the yeast SAGA complex: distinct components involved in structural integrity, nucleosome acetylation, and TATA-binding protein interaction.
Mol. Cell. Biol.
19:86-98 |
| 64. | Strahl, B. D., and C. D. Allis. 2000. The language of covalent histone modifications. Nature 403:41-45[CrossRef][Medline]. |
| 65. |
Struhl, K.
1998.
Histone acetylation and transcriptional regulatory mechanisms.
Genes Dev.
12:599-606 |
| 66. | Tang, J. Y., B. J. Hwang, J. M. Ford, P. C. Hanawalt, and G. Chu. 2000. Xeroderma pigmentosum p48 gene enhances global genomic repair and suppresses UV-induced mutagenesis. Mol. Cell 5:737-744[CrossRef][Medline]. |
| 67. | Teng, Y., S. Li, R. Waters, and S. H. Reed. 1997. Excision repair at the level of the nucleotide in the Saccharomyces cerevisiae MFA2 gene: mapping of where enhanced repair in the transcribed strand begins or ends and identification of only a partial Rad16 requisite for repairing upstream control sequences. J. Mol. Biol. 267:324-337[CrossRef][Medline]. |
| 68. | Thoma, F. 1999. Light and dark in chromatin repair: repair of UV-induced DNA lesions by photolyases and nucleotide excision repair. EMBO J. 18:6585-6598[CrossRef][Medline]. |
| 69. |
Tijsterman, M.,
J. G. Tasseron-de Jong,
P. van de Putte, and J. Brouwer.
1996.
Transcription-coupled and global genome repair in the Saccharomyces cerevisiae RPB2 gene at nucleotide resolution.
Nucleic Acids Res.
24:3499-3506 |
| 70. | Tu, Y., S. Tornaletti, and G. P. Pfeifer. 1996. DNA repair domains within a human gene: selective repair of sequences near the transcription initiation site. EMBO J. 15:675-683[Medline]. |
| 71. | Ura, K., M. Araki, H. Saeki, C. Masutani, T. Ito, S. Iwai, T. Mizukoshi, Y. Kanaeda, and F. Hanaoka. 2001. ATP-dependent chromatin remodeling facilitates nucleotide excision repair of UV-induced DNA lesions in synthetic dinucleosomes. EMBO J. 20:2004-2014[CrossRef][Medline]. |
| 72. | Utley, R. T., K. Ikeda, P. A. Grant, J. Côté, D. J. Steger, A. Eberharter, S. John, and J. L. Workman. 1998. Transcriptional activators direct histone acetyltransferase complexes to nucleosomes. Nature 394:498-502[CrossRef][Medline]. |
| 73. | Vassilev, A., J. Yamauchi, T. Kotani, C. Prives, M. L. Avantaggiati, J. Qin, and Y. Nakatani. 1998. The 400 kDa subunit of the PCAF histone acetylase complex belongs to the ATM superfamily. Cell 2:869-875. |
| 74. |
Vignali, M.,
A. H. Hassan,
K. E. Neely, and J. L. Workman.
2000.
ATP-dependent chromatin remodeling complexes.
Mol. Cell. Biol.
20:1899-1910 |
| 75. | Walker, S. S., J. C. Reese, L. M. Apone, and M. R. Green. 1996. Transcription activation in cells lacking TAFIIs. Nature 383:185-188[CrossRef][Medline]. |
| 76. |
Wallberg, A. E.,
K. E. Neely,
J.-A. Gustafsson,
J. L. Workman,
A. P. H. Wright, and P. A. Grant.
1999.
Histone acetyltransferase complexes can mediate transcriptional activation by the major glucocorticoid receptor activation domain.
Mol. Cell. Biol.
19:5952-5959 |
| 77. | Wieczorek, E., M. Brand, X. Jacq, and L. Tora. 1998. Function of TAFII-containing complex without TBP in transcription by RNA polymerase II. Nature 393:187-191[CrossRef][Medline]. |
| 78. | Winston, F., and P. Sudarsanam. 1998. The SAGA of Spt proteins and transcriptional analysis in yeast: past, present, and future. Cold Spring Harbor Symp. Quant. Biol. 63:553-561[CrossRef][Medline]. |
| 79. |
Xu, W.,
D. G. Edmondson, and S. Y. Roth.
1998.
Mammalian GCN5 and P/CAF acetyltransferases have homologous amino-terminal domains important for recognition of nucleosomal substrates.
Mol. Cell. Biol.
18:5659-5669 |
| 80. | Xu, W., D. G. Edmondson, Y. A. Evrard, M. Wakamiya, R. R. Behringer, and S. Y. Roth. 2000. Loss of Gcn5l2 leads to increased apoptosis and mesodermal defects during mouse development. Nat. Genet. 26:229-232[CrossRef][Medline]. |
| 81. |
Yamauchi, T.,
J. Yamauchi,
T. Kuwata,
T. Tamura,
T. Yamashita,
N. Bae,
H. Westphal,
K. Ozato, and Y. Nakatani.
2000.
Distinct but overlapping roles of histone acetylase PCAF and of the closely related PCAF-B/GCN5 in mouse embryogenesis.
Proc. Natl. Acad. Sci. USA
97:11303-11306 |
| 82. | Yang, X.-J., V. V. Ogryzko, J. Nishikawa, B. H. Howard, and Y. Nakatani. 1996. A p300/CBP-associated factor that competes with the adenoviral oncoprotein E1A. Nature 382:319-324[CrossRef][Medline]. |
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