Cooperative interaction of an initiator-binding transcription initiation factor and the helix–loop–helix activator USF

Abstract

Transcription initiation by mammalian RNA polymerase II is effected by multiple common factors interacting through minimal promoter elements and regulated by gene-specific factors interacting with distal control elements. Minimal promoter elements that can function independently or together, depending on the specific promoter, include the upstream TATA box and a pyrimidine-rich initiator (Inr) overlapping the transcription start site. The binding of TFIID to the TATA element promotes the assembly of other factors into a preinitiation complex but factors which function at the Inr have not been defined. We show here that a novel factor (TFII-I) binds specifically to Inr elements, supports basal transcription from the adenovirus major late promoter and is immunologically related to the helix-loop-helix activator USF. We further show that TFII-I also binds to the upstream high-affinity USF site (E box), that USF also binds to the Inr, and that TFII-I and USF interact cooperatively at both Inr and E box sites. Thus, TFII-I represents a novel type of transcription initiation factor whose interactions at multiple promoter elements may aid novel communication mechanisms between upstream regulatory factors and the general transcriptional machinery.

Transcription of the juvenile hormone esterase gene under the control of both an initiator and AT-rich motif

“…see [29]). A number of studies have identified various proteins as binding at or near the initiator motif, such as RNA polymerase II [3], YY1 [30], E2f(HIP1) [5], TAFII150 [1], USF [6], TFIIA [7], TFII-I [8,9] or TFIID itself [10][11][12], but the actual mechanisms of joint interaction of these proteins with the initiator (binding protein) and TFIID are obscure. The role and form of the TATA box are also more complicated than originally conceived.…”

“…TAFII28 and RXR ; [2]). In a number of cases there also appears to be specific binding by factors other than TBP to an ' initiator ' motif downstream from the TBP-binding site [3][4][5][6][7][8][9][10][11][12]. There is increasing evidence that particular DNA sequences in the core promoter, other than the TBP-and initiator-binding motifs, play a pivotal role in controlling whether a particular TBP\TAFII complex [13] or other non-TFIID factor (e.g.…”

Transcription of the HS2 Enhancer toward a cis-Linked Gene Is Independent of the Orientation, Position, and Distance of the Enhancer Relative to the Gene

“…Indeed, the HS2 sequence has been shown to contain DNA motifs that bind to many transcription factors such as NF-E2 and Ap-1 (33,35,46,48,49), GATA (22,39,49), YY1 (5,12), and USF (4,5,12,40,49). NF-E2, AP-1, and GATA have been suggested to be capable of recruiting and assembling the transcriptional machinery (16,53), and USF and YY1 have been reported to be capable of stimulating transcriptional initiation from their respective binding sites (25,26,41,44). The presence in the enhancer complex of transcription factors intimately associated with the transcriptional machinery suggests that the HS2 enhancer complex may also constitute a transcriptional complex (6) and thus may be capable of initiating enhancer transcription from defined sites in the HS2 enhancer.…”

Myc represses the p21 (WAF1/CIP1) promoter and interacts with Sp1/Sp3

“…The Inr element is usually defined as a weak consensus YYCAYYYYY, where Y is a pyrimidine base (32). The initiator binding protein TFII-I stimulates basal transcription from the Inr element (33). Myc can bind TFII-I and form a complex associated with the Inr sequence that prevents transcriptional activation from Inr (34).…”