This Article Full Text Full Text (PDF) Other Versions of this Article: MCB.00369-08v1 28/13/4275    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 Li, Y. Articles by Andrews, G. K. PubMed PubMed Citation Articles by Li, Y. Articles by Andrews, G. K.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, July 2008, p. 4275-4284, Vol. 28, No. 13
0270-7306/08/$08.00+0     doi:10.1128/MCB.00369-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Zinc-Induced Formation of a Coactivator Complex Containing the Zinc-Sensing Transcription Factor MTF-1, p300/CBP, and Sp1

Yong Li,¹ Tomoki Kimura,^1, Ryan W. Huyck,² John H. Laity,² and Glen K. Andrews^1*

Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160-7421,¹ Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri—Kansas City, Kansas City, Missouri 64110-2499²

Received 4 March 2008/ Returned for modification 1 April 2008/ Accepted 24 April 2008

Herein, the mechanisms of transactivation of gene expression by mouse metal response element-binding transcription factor 1 (MTF-1) were investigated. Evidence obtained from coimmunoprecipitation assays revealed that exposure of the cells to zinc resulted in the rapid formation of a multiprotein complex containing MTF-1, the histone acetyltransferase p300/CBP, and the transcription factor Sp1. Down-regulation of endogenous p300 expression by small interfering RNA transfection significantly decreased zinc-dependent metallothionein I (MT-I) gene transcription without altering induction of zinc transporter 1 (ZnT1). MTF-1 independently facilitated the recruitment of Sp1 and p300 to the protein complex in response to zinc. Mutagenesis demonstrated that the acidic domain, one of three transactivation domains of MTF-1, is required for recruitment of p300 but not Sp1 as well as for zinc-dependent activation of MT-I gene transcription. Furthermore, mutation of leucine residues (LA) within a nuclear exclusion signal in the MTF-1 acidic domain impaired recruitment of p300 and zinc-dependent activation of the MT-I gene. Nuclear magnetic resonance characterization of an isolated protein fragment corresponding to the MTF-1 acidic region demonstrated that this region is largely unstructured in the presence and absence of excess stoichiometric amounts of zinc. This suggests that the mechanism by which MTF-1 recruits p300 to this complex involves extrinsic-zinc-dependent steps. These studies reveal a novel zinc-responsive mechanism requiring an acidic region of MTF-1 that functions as a nuclear exclusion signal as well as participating in formation of a coactivator complex essential for transactivation of MT-I gene expression.

Published ahead of print on 5 May 2008.

Present address: Department of Toxicology, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.