An Array of Coactivators Is Required for Optimal Recruitment of TATA Binding Protein and RNA Polymerase II by Promoter-Bound Gcn4p
AUTOR(ES)
Qiu, Hongfang
FONTE
American Society for Microbiology
RESUMO
Wild-type transcriptional activation by Gcn4p is dependent on multiple coactivators, including SAGA, SWI/SNF, Srb mediator, CCR4-NOT, and RSC, which are all recruited by Gcn4p to its target promoters in vivo. It was not known whether these coactivators are required for assembly of the preinitiation complex (PIC) or for subsequent steps in the initiation or elongation phase of transcription. We find that mutations in subunits of these coactivators reduce the recruitment of TATA binding protein (TBP) and RNA polymerase II (Pol II) by Gcn4p at ARG1, ARG4, and SNZ1, implicating all five coactivators in PIC assembly at Gcn4p target genes. Recruitment of Pol II at SNZ1 and ARG1 was eliminated by mutations in TBP or by deletion of the TATA box, indicating that TBP binding is a prerequisite for Pol II recruitment by Gcn4p. However, several mutations in SAGA subunits and deletion of SRB10 had a greater impact on promoter occupancy of Pol II versus TBP, suggesting that SAGA and Srb mediator can promote Pol II binding independently of their stimulatory effects on TBP recruitment. Our results reveal an unexpected complexity in the cofactor requirements for the enhancement of PIC assembly by a single activator protein.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=400468Documentos Relacionados
- A Multiplicity of Coactivators Is Required by Gcn4p at Individual Promoters In Vivo
- Human cytomegalovirus IE86 protein interacts with promoter-bound TATA-binding protein via a specific region distinct from the autorepression domain.
- The Gcn4p Activation Domain Interacts Specifically In Vitro with RNA Polymerase II Holoenzyme, TFIID, and the Adap-Gcn5p Coactivator Complex
- Human Mediator Enhances Activator-Facilitated Recruitment of RNA Polymerase II and Promoter Recognition by TATA-Binding Protein (TBP) Independently of TBP-Associated Factors
- Enhancer-dependent transcription of the epsilon-globin promoter requires promoter-bound GATA-1 and enhancer-bound AP-1/NF-E2.