title: TBP domain symmetry in basal and activated archaeal transcription.
abstract: The TATA box binding protein (TBP) is the platform for assembly of archaeal and eukaryotic transcription preinitiation complexes. Ancestral gene duplication and fusion events have produced the saddle-shaped TBP molecule, with its two direct-repeat subdomains and pseudo-two-fold symmetry. Collectively, eukaryotic TBPs have diverged from their present-day archaeal counterparts, which remain highly symmetrical. The similarity of the N- and C-halves of archaeal TBPs is especially pronounced in the Methanococcales and Thermoplasmatales, including complete conservation of their N- and C-terminal stirrups; along with helix H'1, the C-terminal stirrup of TBP forms the main interface with TFB/TFIIB. Here, we show that, in stark contrast to its eukaryotic counterparts, multiple substitutions in the C-terminal stirrup of Methanocaldococcus jannaschii (Mja) TBP do not completely abrogate basal transcription. Using DNA affinity cleavage, we show that, by assembling TFB through its conserved N-terminal stirrup, Mja TBP is in effect ambidextrous with regard to basal transcription. In contrast, substitutions in either its N- or the C-terminal stirrup abrogate activated transcription in response to the Lrp-family transcriptional activator Ptr2.
authors.affiliation: Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0634, USA. mouham@biomail.ucsd.edu
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ouhammouch
authors.forename: Winfried
authors.initials: W
authors.lastname: Hausner
authors.forename: E Peter
authors.initials: EP
authors.lastname: Geiduschek
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism*; D019641:DNA, Archaeal / Q000378:metabolism; D019848:Gene Expression Regulation, Archaeal; D017015:Methanococcales / Q000235:genetics / Q000378:metabolism*; D035181:TATA-Box Binding Protein / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D019843:Archaeal Proteins; D019641:DNA, Archaeal; D035181:TATA-Box Binding Protein