Affiliation:
1. Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84132
Abstract
ABSTRACT
We use chromatin immunoprecipitation assays to show that the Gcn5 histone acetyltransferase in SAGA is required for SWI/SNF association with the
HO
promoter and that binding of SWI/SNF and SAGA are interdependent. Previous results showed that SWI/SNF binding to
HO
was Gcn5 independent, but that work used a strain with a mutation in the Ash1 daughter-specific repressor of
HO
expression. Here, we show that Ash1 functions as a repressor that inhibits SWI/SNF binding and that Gcn5 is required to overcome Ash1 repression in mother cells to allow
HO
transcription. Thus, Gcn5 facilitates SWI/SNF binding by antagonizing Ash1. Similarly, a mutation in
SIN3
, like an
ash1
mutation, allows both
HO
expression and SWI/SNF binding in the absence of Gcn5. Although Ash1 has recently been identified in a Sin3-Rpd3 complex, our genetic analysis shows that Ash1 and Sin3 have distinct functions in regulating
HO
. Analysis of mutant strains shows that SWI/SNF binding and
HO
expression are correlated and regulated by histone acetylation. The defect in
HO
expression caused by a mutant SWI/SNF with a Swi2(E834K) substitution can be partially suppressed by
ash1
or
spt3
mutation or by a gain-of-function V71E substitution in the TATA-binding protein (TBP). Spt3 inhibits TBP binding at
HO
, and genetic analysis suggests that Spt3 and TBP(V71E) act in the same pathway, distinct from that of Ash1. We have detected SWI/SNF binding at the
HO
TATA region, and our results suggest that SWI/SNF, either directly or indirectly, facilitates TBP binding at
HO
.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
58 articles.
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