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Mol. Cell. Biol., 01 1997, 287-295, Vol 17, No. 1
JM Madison and F Winston
Spt3 of Saccharomyces cerevisiae is a factor required for normal
transcription from particular RNA polymerase II-dependent promoters.
Previous genetic and biochemical analyses have shown that Spt3 interacts
with the yeast TATA-binding protein (TBP). To identify other factors that
might interact with Spt3, we have screened for mutations that, in
combination with an spt3 null mutation, lead to inviability. In this way,
we have identified a mutation in MOT1, which encodes an ATP-dependent
inhibitor of TBP binding to TATA boxes: Previous analyses suggested that
Mot1 causes repression in vivo. However, our analysis of mot1 mutants shows
that, similar to spt3 mutants, they have decreased levels of transcription
from certain genes, suggesting that Mot1 may function as an activator in
vivo. In addition, mot1 mutants have other phenotypes in common with spt3
delta mutants, including suppression of the insertion mutation his4-912
delta. Motivated by these Spt3-Mot1 genetic interactions, we tested for
genetic interactions between Spt3 and the general transcription factor
TFIIA. TFIIA has been shown previously to be functionally related to Mot1.
We found that overexpression of TFIIA partially suppresses an spt3 delta
mutation, that toa1 mutants have Spt-phenotypes, and that spt3 delta toa1
double mutants are inviable. We believe that, taken together, these data
suggest that Spt3, Mot1, and TFIIA cooperate to regulate TBP-DNA
interactions, perhaps at the level of TATA box selection in vivo.
Copyright © 1997, American Society for Microbiology
Evidence that Spt3 functionally interacts with Mot1, TFIIA, and TATA- binding protein to confer promoter-specific transcriptional control in Saccharomyces cerevisiae
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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