Core promoter elements recognized by transcription factor IIB

The general transcription factor TFIIB (transcription factor IIB) plays a critical role in the assembly of the RNA polymerase II pre-initiation complex. TFIIB can make sequence-specific DNA contacts both upstream and downstream of the TATA box. This has led to the definition of two core promoter BREs (TFIIB-recognition elements), one upstream [BRE^u (upstream BRE)] and one downstream of TATA box [BRE^d (downstream BRE)]. TFIIB–BRE^u and TFIIB–BRE^d contacts are mediated by two independent DNA-recognition motifs within the core domain of TFIIB. Both the BRE^u and the BRE^d modulate the transcriptional potency of a promoter. However, the net effect of the BREs on promoter activity is dependent on the specific blend of elements present within a core promoter.