DISTINCT SUBDOMAINS OF HUMAN TAF(II)130 ARE REQUIRED FOR INTERACTIONSWITH GLUTAMINE-RICH TRANSCRIPTIONAL ACTIVATORS

TFIID is a multiprotein complex consisting of the TATA box binding pro tein and multiple tightly associated proteins (TAP(II)s) that are requ ired for transcription by selected activators. We previously reported cloning and partial characterization of human TAF(II)130 (hTAF(II)130) . The central domain of hTAF(II)130 contains four glutamine-rich regio ns, designated Q1 to Q4, that are involved in interactions with the tr anscriptional activator Spl. Mutational analysis has revealed specific regions within the glutamine-rich (Q1 to QI) central region of hTAF(I I)130 that are required for interaction with distinct activation domai ns. We tested amino- and cariboxyl-terminal deletions of hTAF(II)130 f or interaction with Sp1 activation domains A and B (Sp1A and Sp1B) and the N-terminal activation domain of CREB (CREB-N) by using the yeast two-hybrid system. Our results indicate that Sp1B interacts almost exc lusively with the Q1 region of hTAF(II)130. in contrast, Sp1A makes mu ltiple contacts with Q1 to Q4 of hTAF(II)130, while CREB-N interacts p rimarily with the Q1-Q2 hTAF(II)130 subdomain. Consistent with these i nteraction studies, overexpression of the Q1-to-Q4 region in HeLa cell s inhibits Sp1- bmt mot VP16-mediated transcriptional activation. Thes e findings indicate that the Q1-to-Q4 region of hTAF(II)130 is require d for Sp1-mediated transcriptional enhancement in mammalian cells and that different activation domains target distinct subdomains of hTAF(I I)130.