Molecular requirements for gene expression mediated by targeted histone acetyltransferases.
Histone acetyltransferases (HATs) play fundamental roles in regulating gene expression. HAT complexes with distinct subunit composition and substrate specificity act on chromatin-embedded genes with different promoter architecture and chromosomal locations. Because requirements for HAT complexes vary, a central question in transcriptional regulation is how different HAT complexes function in different chromosomal contexts. Here, we have tested the ability of targeted yeast HATs to regulate gene expression of an epigenetically silenced locus. Of a panel of HAT fusion proteins targeted to a telomeric reporter gene, Sas3p and Gcn5p selectively increased expression of the silenced gene. Reporter gene expression was not solely dependent on acetyltransferase activity of the targeted HAT. Further analysis of Gcn5p-mediated gene expression revealed collateral requirements for HAT complex subunits Spt8p and Spt3p, which interact with TATA-binding protein, and for a gene-specific transcription factor. These data demonstrate plasticity of gene expression mediated by HATs upon encountering novel promoter architecture and chromatin context. The telomeric location of the reporter gene used in these studies also provides insight into the molecular requirements for heterochromatin boundary formation and for overcoming transcriptional silencing.
Jacobson
Sandra
S
Division of Biological Sciences, Section of Molecular Biology and Center for Molecular Genetics, UCSD Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA. sandij@biomail.ucsd.edu
Pillus
Lorraine
L
D000123:Acetyltransferases / Q000502:physiology*; D002843:Chromatin; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D020868:Gene Silencing; D017930:Genes, Reporter; D051548:Histone Acetyltransferases; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D013379:Substrate Specificity; D016615:Telomere; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic
D002843:Chromatin; D004268:DNA-Binding Proteins; D021122:Protein Subunits; C075582:SPT3 protein, S cerevisiae; C089445:SPT8 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000123:Acetyltransferases; D051548:Histone Acetyltransferases; D011494:Protein Kinases