This Article Full Text Full Text (PDF) Other Versions of this Article: EC.00233-08v1 7/10/1649    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 He, Q. Articles by Morse, R. H. PubMed PubMed Citation Articles by He, Q. Articles by Morse, R. H.

 Previous Article  |  Next Article 

Eukaryotic Cell, October 2008, p. 1649-1660, Vol. 7, No. 10
1535-9778/08/$08.00+0     doi:10.1128/EC.00233-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Dispersed Mutations in Histone H3 That Affect Transcriptional Repression and Chromatin Structure of the CHA1 Promoter in Saccharomyces cerevisiae

Department of Biomedical Sciences, State University of New York at Albany School of Public Health,¹ Laboratory of Developmental Genetics, Wadsworth Center, New York State Department of Health, Albany, New York 12201-2002²

Received 15 July 2008/ Accepted 16 July 2008

The histone H3 amino terminus, but not that of H4, is required to prevent the constitutively bound activator Cha4 from remodeling chromatin and activating transcription at the CHA1 gene in Saccharomyces cerevisiae. Here we show that neither the modifiable lysine residues nor any specific region of the H3 tail is required for repression of CHA1. We then screened for histone H3 mutations that cause derepression of the uninduced CHA1 promoter and identified six mutants, three of which are also temperature-sensitive mutants and four of which exhibit a sin^– phenotype. Histone mutant levels were similar to that of wild-type H3, and the mutations did not cause gross alterations in nucleosome structure. One specific and strongly derepressing mutation, H3 A111G, was examined in depth and found to cause a constitutively active chromatin configuration at the uninduced CHA1 promoter as well as at the ADH2 promoter. Transcriptional derepression and altered chromatin structure of the CHA1 promoter depend on the activator Cha4. These results indicate that modest perturbations in distinct regions of the nucleosome can substantially affect the repressive function of chromatin, allowing activation in the absence of a normal inducing signal (at CHA1) or of Swi/Snf (resulting in a sin^– phenotype).

Published ahead of print on 25 July 2008.