This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: MCB.00127-08v1 28/14/4576    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by French, S. L. Articles by Beyer, A. L. PubMed PubMed Citation Articles by French, S. L. Articles by Beyer, A. L.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, July 2008, p. 4576-4587, Vol. 28, No. 14
0270-7306/08/$08.00+0     doi:10.1128/MCB.00127-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Visual Analysis of the Yeast 5S rRNA Gene Transcriptome: Regulation and Role of La Protein ^,

Sarah L. French,¹ Yvonne N. Osheim,¹ David A. Schneider,^2, Martha L. Sikes,¹ Cesar F. Fernandez,³ Laura A. Copela,³ Vikram A. Misra,^4, Masayasu Nomura,² Sandra L. Wolin,³ and Ann L. Beyer^1*

Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908,¹ Department of Biological Chemistry, University of California—Irvine, Irvine, California 92697,² Departments of Cell Biology and Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06536,³ Departments of Biochemistry and Mathematics, University of Maryland Baltimore County, Baltimore, Maryland 21250⁴

Received 23 January 2008/ Returned for modification 4 March 2008/ Accepted 2 May 2008

5S rRNA genes from Saccharomyces cerevisiae were examined by Miller chromatin spreading, representing the first quantitative analysis of RNA polymerase III genes in situ by electron microscopy. These very short genes, 132 nucleotides (nt), were engaged by one to three RNA polymerases. Analysis in different growth conditions and in strains with a fourfold range in gene copy number revealed regulation at two levels: number of active genes and polymerase loading per gene. Repressive growth conditions (presence of rapamycin or postexponential growth) led first to fewer active genes, followed by lower polymerase loading per active gene. The polymerase III elongation rate was estimated to be in the range of 60 to 75 nt/s, with a reinitiation interval of 1.2 s. The yeast La protein, Lhp1, was associated with 5S genes. Its absence had no discernible effect on the amount or size of 5S RNA produced yet resulted in more polymerases per gene on average, consistent with a non-rate-limiting role for Lhp1 in a process such as polymerase release/recycling upon transcription termination.

Published ahead of print on 12 May 2008.

Supplemental material for this article may be found at http://mcb.asm.org/.

Present address: Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294.

Present address: Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville VA 22908.