title: Structure of a (Cys3His) zinc ribbon, a ubiquitous motif in archaeal and eucaryal transcription.
abstract: Transcription factor IIB (TFIIB) is an essential component in the formation of the transcription initiation complex in eucaryal and archaeal transcription. TFIIB interacts with a promoter complex containing the TATA-binding protein (TBP) to facilitate interaction with RNA polymerase II (RNA pol II) and the associated transcription factor IIF (TFIIF). TFIIB contains a zinc-binding motif near the N-terminus that is directly involved in the interaction with RNA pol II/TFIIF and plays a crucial role in selecting the transcription initiation site. The solution structure of the N-terminal residues 2-59 of human TFIIB was determined by multidimensional NMR spectroscopy. The structure consists of a nearly tetrahedral Zn(Cys)3(His)1 site confined by type I and "rubredoxin" turns, three antiparallel beta-strands, and disordered loops. The structure is similar to the reported zinc-ribbon motifs in several transcription-related proteins from archaea and eucarya, including Pyrococcus furiosus transcription factor B (PfTFB), human and yeast transcription factor IIS (TFIIS), and Thermococcus celer RNA polymerase II subunit M (TcRPOM). The zinc-ribbon structure of TFIIB, in conjunction with the biochemical analyses, suggests that residues on the beta-sheet are involved in the interaction with RNA pol II/TFIIF, while the zinc-binding site may increase the stability of the beta-sheet.
authors.affiliation: Center for Metalloenzyme Studies, University of Georgia, Athens 30602-2556, USA.
authors.forename: H T
authors.initials: HT
authors.lastname: Chen
authors.forename: P
authors.initials: P
authors.lastname: Legault
authors.forename: J
authors.initials: J
authors.lastname: Glushka
authors.forename: J G
authors.initials: JG
authors.lastname: Omichinski
authors.forename: R A
authors.initials: RA
authors.lastname: Scott
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001105:Archaea / Q000235:genetics*; D003545:Cysteine / Q000737:chemistry*; D005057:Eukaryotic Cells / Q000378:metabolism; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D035581:Transcription Factor TFIIB; D014157:Transcription Factors / Q000737:chemistry; D014158:Transcription, Genetic; D015032:Zinc / Q000737:chemistry*
chemical_list: D035581:Transcription Factor TFIIB; D014157:Transcription Factors; D006639:Histidine; D015032:Zinc; D003545:Cysteine