TFIIA interacts with TFIID via association with TATA-binding protein and TAF40

TFIIA and TATA-binding protein (TBP) associate directly at the TATA element of genes transcribed by RNA polymerase II. In vivo, TBP is complexed with approximately 14 TBP-associated factors (TAFs) to form the general transcri ption factor TFIID. How TFIIA and TFIID communicate is not well understood. We show that in addition to making direct contacts with TBP, yeast TAF40 i nteracts directly and specifically with TFIIA Mutational analyses of the To a2 subunit of TFIIA indicate that loss of functional interaction between TF IIA and TAF40 results in conditional growth phenotypes and defects in trans cription. These results demonstrate that the TFIIA-TAF40 interaction is imp ortant in vivo and indicate a functional role for TAF40 as a bridging facto r between TFIIA and TFIID.