Recruitment of an RNA polymerase II complex is mediated by the constitutive activation domain in CREB, independently of CREB phosphorylation

The cAMP response element binding protein (CREB) is a bifunctional transcri ption activator, exerting its effects through a constitutive activation dom ain (CAD) and a distinct kinase inducible domain (KID), which requires phos phorylation of Ser-133 for activity. Both CAD and phospho-KID have been pro posed to recruit polymerase complexes, but this has not been directly teste d. Here, we show that the entire CREB activation domain or the CAD enhanced recruitment of a complex containing TFIID, TFIIB, and RNA polymerase II to a linked promoter. The nuclear extracts used mediated protein kinase A (PK A)-inducible transcription, but phosphorylation of CRG (both of the CREB ac tivation domains fused to the GaI4 DNA binding domain) or KID-G4 did not me diate recruitment of a complex, and mutation of the PKA site in CRG abolish ed transcription induction by PKA but had no effect upon recruitment. The C REB-binding protein (CBP) was not detected in the recruited complex Our res ults support a model for transcription activation in which the interaction between the CREB CAD and hTAFII130 of TFIID promotes the recruitment of a p olymerase complex to the promoter.