Human General Transcription Factor TFIIB: Conformational Variability and Interaction with VP16 Activation Domain
详细信息 查看全文
- 作者：Fumiaki Hayashi ; Rieko Ishima ; Dingjiang Liu ; Kit I. Tong ; Sungjoon Kim ; Danny Reinberg ; Stefan Bagby ; and Mitsuhiko Ikura
- 刊名：Biochemistry
- 出版年：1998
- 出版时间：June 2, 1998
- 年：1998
- 卷：37
- 期：22
- 页码：7941 - 7951
- 全文大小：290K
- 年卷期：v.37,no.22(June 2, 1998)
- ISSN：1520-4995
文摘
Human TFIIB, an essential factor in transcription ofprotein-coding genes by RNA polymeraseII, consists of an amino-terminal zinc binding domain (TFIIBn)connected by a linker of about 60 residuesto a carboxy-terminal core domain (TFIIBc). The TFIIB core domainhas two internally repeated motifs,each comprising five 
-helices arranged as in the cyclin box.Compared to the crystal structure of TFIIBcin complex with TBP and a TATA-containing oligonucleotide, theNMR-derived solution structure offree TFIIBc is more compact, with a different repeat-repeatorientation and a significantly shorter firsthelix in the second repeat. Analysis of backbone 15Nrelaxation parameters indicates the presence ofrelatively large amplitude, nanosecond time-scale motions in the TFIIBcinterrepeat linker and structuralfluctuations throughout the backbone. Interaction of TFIIBc withthe acidic activation domain of VP16or with TFIIBn induces 1H-15N chemical shiftand line width changes concentrated in the first repeat,interrepeat linker and the first helix of the second repeat. Theseresults suggest that TFIIB is somewhatpliable and that the conformation of the C-terminal core domain can bemodulated by interaction with theN-terminal zinc binding domain. Furthermore, binding of the VP16activation domain may promoteTFIIBc conformations primed for binding to a TBP-DNAcomplex.
-helices arranged as in the cyclin box.Compared to the crystal structure of TFIIBcin complex with TBP and a TATA-containing oligonucleotide, theNMR-derived solution structure offree TFIIBc is more compact, with a different repeat-repeatorientation and a significantly shorter firsthelix in the second repeat. Analysis of backbone 15Nrelaxation parameters indicates the presence ofrelatively large amplitude, nanosecond time-scale motions in the TFIIBcinterrepeat linker and structuralfluctuations throughout the backbone. Interaction of TFIIBc withthe acidic activation domain of VP16or with TFIIBn induces 1H-15N chemical shiftand line width changes concentrated in the first repeat,interrepeat linker and the first helix of the second repeat. Theseresults suggest that TFIIB is somewhatpliable and that the conformation of the C-terminal core domain can bemodulated by interaction with theN-terminal zinc binding domain. Furthermore, binding of the VP16activation domain may promoteTFIIBc conformations primed for binding to a TBP-DNAcomplex.