Distinct Subdomains of Human TAFII130 Are Required for Interactions with Glutamine-Rich Transcriptional Activators

TFIID is a multiprotein complex consisting of the TATA box binding protein and multiple tightly associated proteins (TAFIIs) that are required for transcription by selected activators. We previously reported cloning and partial characterization of human TAFII130 (hTAFII130). The central domain of hTAFII130 contains four glutamine-rich regions, designated Q1 to Q4, that are involved in interactions with the transcriptional activator Sp1. Mutational analysis has revealed specific regions within the glutamine-rich (Q1 to Q4) central region of hTAFII130 that are required for interaction with distinct activation domains. We tested amino- and carboxyl-terminal deletions of hTAFII130 for 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 exclusively with the Q1 region of hTAFII130. In contrast, Sp1A makes multiple contacts with Q1 to Q4 of hTAFII130, while CREB-N interacts primarily with the Q1-Q2 hTAFII130 subdomain. Consistent with these interaction studies, overexpression of the Q1-to-Q4 region in HeLa cells inhibits Sp1- but not VP16-mediated transcriptional activation. These findings indicate that the Q1-to-Q4 region of hTAFII130 is required for Sp1-mediated transcriptional enhancement in mammalian cells and that different activation domains target distinct subdomains of hTAFII130.