TFIIA-TAF regulatory interplay: NMR evidence for overlapping binding siteson TBP

TATA box binding protein (TBP)-promoter interaction nucleates assembly of t he RNA polymerase II transcription initiation complex. Transcription factor IIA (TFIIA) stabilizes the TBP-promoter complex whereas the N-terminal dom ain of the largest TAF(II) inhibits TBP-promoter interaction. We have mappe d the interaction sites on TBP of Drosophila TAF(II)230 and yeast TFIIA (co mprising two subunits, TOA1 and TOA2), using nuclear magnetic resonance (NM R), and also report structural evidence that subdomain II of the TAF(II)230 N-terminal inhibitory domain and TFIIA have overlapping binding sites on t he convex surface of TBP, Together with previous mutational and biochemical data, our NMR results indicate that subdomain II augments subdomain I-medi ated inhibition of TBP function by blocking TBP-TFIIA interaction. (C) 2000 Federation of European Biochemical Societies.