title: Structural evidence for a common zinc binding domain in archaeal and eukaryal transcription factor IIB proteins.
abstract: X-ray absorption spectroscopy has been used to compare the metal coordination of the N-terminal zinc binding domain of eukaryal human transcription factor (TF) IIB to the previously reported structure of archaeal Pyrococcus furiosus (Pf) TFB. Full length and N-terminal fragments for both PfTFB and human TFIIB were cloned, expressed, and purified. The [C10H] variant of PfTFB was constructed to resemble the metal binding motif of higher eukaryal TFIIB proteins by mutating the second cysteine ligand to a histidine. All five proteins bind zinc in a 1:1 ratio. Zn X-ray absorption spectroscopy of human TFIIB and [C10H]PfTFB mutant are consistent with ZnS3(N,O) ligation, and further suggest that the N/O ligand is an imidazole.
authors.affiliation: Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens 30602-2556, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Colangelo
authors.forename: L M
authors.initials: LM
authors.lastname: Lewis
authors.forename: N J
authors.initials: NJ
authors.lastname: Cosper
authors.forename: R A
authors.initials: RA
authors.lastname: Scott
mesh_terms: D015502:Absorptiometry, Photon; D001105:Archaea / Q000235:genetics; D005057:Eukaryotic Cells / Q000201:enzymology; D006801:Humans; D008024:Ligands; D011485:Protein Binding; D035581:Transcription Factor TFIIB; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism*; D014170:Transformation, Genetic / Q000235:genetics; D015032:Zinc / Q000378:metabolism*
chemical_list: D008024:Ligands; D035581:Transcription Factor TFIIB; D014157:Transcription Factors; D015032:Zinc