Sgf29p facilitates the recruitment of TATA box binding protein but does not alter SAGA's global structural integrity in vivo.
Although Sgf29p has been biochemically implicated as a component of SAGA (Spt-Ada-Gcn5 acetyltransferase), its precise mechanism of action in transcription is not clearly understood in vivo. Here, using a formaldehyde-based in vivo cross-linking and chromatin immunoprecipitation (ChIP) assay in conjunction with transcriptional and mutational analyses, we show that Sgf29p along with other SAGA components is recruited to the upstream activating sequence (UAS) of a SAGA-regulated gene, GAL1, in an activation domain-dependent manner. However, Sgf29p does not alter the recruitment of Spt20p that maintains the overall structural and functional integrity of SAGA. The recruitment of other SAGA components such as TAF10p, TAF12p, and Ubp8p to the GAL1 UAS is also not altered in the absence of Sgf29p. Interestingly, we find that the recruitment of TBP (TATA box binding protein that nucleates the assembly of general transcription factors to form the preinitiation complex for transcriptional initiation) to the core promoter of GAL1 is weakened in Δsgf29. Likewise, Sgf29p also enhances the recruitment of TBP to other SAGA-regulated promoters. Such weakening of recruitment of TBP to these promoters subsequently decreases the level of transcription. Taken together, these results support the idea that SAGA-associated Sgf29p facilitates the recruitment of TBP (and hence transcription) without altering the global structural integrity of SAGA in vivo.
Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901, United States.
Abhijit
A
Shukla
Shweta
S
Lahudkar
Geetha
G
Durairaj
Sukesh R
SR
Bhaumik
D000107:Acetylation; D047369:Chromatin Immunoprecipitation; D004252:DNA Mutational Analysis; D051548:Histone Acetyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D035181:TATA-Box Binding Protein / Q000378:metabolism*; D014158:Transcription, Genetic
D006657:Histones; D029701:Saccharomyces cerevisiae Proteins; D035181:TATA-Box Binding Protein; D051548:Histone Acetyltransferases; C553425:Sgf29 protein, S cerevisiae