SALSA, a Variant of Yeast SAGA, Contains Truncated Spt7, Which Correlates with Activated Transcription

Spt-Ada-Gcn5 acetyltransferase (SAGA) is a previously described histone acetyltransferase/transcriptional coactivator complex in yeast. At promoters of certain genes (HIS3 and TRP3), SAGA has an inhibitory function involving a nonproductive TATA-binding protein interaction mediated by the Spt3 and S...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2002-09, Vol.99 (18), p.11622-11627
Main Authors: Sterner, David E., Belotserkovskaya, Rimma, Berger, Shelley L.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Antibodies
Base Sequence
Biochemistry
Biological Sciences
Blotting, Western
Fungal Proteins - metabolism
Gels
Gene expression regulation
Genes
Genetic mutation
Histones
Molecular Sequence Data
Mutation
Plasmids
Precipitin Tests
Proteins
Saccharomyces cerevisiae - metabolism
Saccharomyces cerevisiae Proteins
Salsas
Transcription Factors - chemistry
Transcription Factors - genetics
Transcription Factors - metabolism
Transcription Factors - physiology
Transcription, Genetic
Truncation
Yeast
Yeasts
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Summary:Spt-Ada-Gcn5 acetyltransferase (SAGA) is a previously described histone acetyltransferase/transcriptional coactivator complex in yeast. At promoters of certain genes (HIS3 and TRP3), SAGA has an inhibitory function involving a nonproductive TATA-binding protein interaction mediated by the Spt3 and Spt8 subunits. Related to this, Spt8-less SAGA is a major form of the complex under activating conditions for these genes. In the present study, we purify this activation-specific complex, called SALSA (SAGA altered, Spt8 absent). Besides lacking Spt8, SALSA contains Spt7 subunit that is truncated. Examining the role of this subunit, we find that C-terminally truncated SPT7 resulted in derepressed HIS3 transcription. Furthermore, when grown in rich media (repressing conditions), wild-type cells yielded predominantly SAGA, but Spt7 C-terminal truncations resulted primarily in a form of complex similar to SALSA. Thus, SALSA-like structure and activating function can be partially recapitulated in yeast by truncating the C terminus of Spt7. Overall, these results lead to a model that for a subset of promoters SAGA is inhibitory through Spt3, Spt8, and an Spt8-interacting subdomain of Spt7, whereas SALSA is a form of complex for positive transcriptional regulation. These data clarify a mechanism by which a transcriptional regulatory complex can switch between positive and negative modulation.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.182021199