title: Archaeal transcription: function of an alternative transcription factor B from Pyrococcus furiosus.
abstract: The genome of the hyperthermophile archaeon Pyrococcus furiosus encodes two transcription factor B (TFB) paralogs, one of which (TFB1) was previously characterized in transcription initiation. The second TFB (TFB2) is unusual in that it lacks recognizable homology to the archaeal TFB/eukaryotic TFIIB B-finger motif. TFB2 functions poorly in promoter-dependent transcription initiation, but photochemical cross-linking experiments indicated that the orientation and occupancy of transcription complexes formed with TFB2 at the strong gdh promoter are similar to the orientation and occupancy of transcription complexes formed with TFB1. Initiation complexes formed by TFB2 display a promoter opening defect that can be bypassed with a preformed transcription bubble, suggesting a mechanism to explain the low TFB2 transcription activity. Domain swaps between TFB1 and TFB2 showed that the low activity of TFB2 is determined mainly by its N terminus. The low activity of TFB2 in promoter opening and transcription can be partially relieved by transcription factor E (TFE). The results indicate that the TFB N-terminal region, containing conserved Zn ribbon and B-finger motifs, is important in promoter opening and that TFE can compensate for defects in the N terminus through enhancement of promoter opening.
authors.affiliation: Department of Biology, Portland State University, P.O. Box 751, Portland, OR 97207, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Micorescu
authors.forename: Sebastian
authors.initials: S
authors.lastname: Grünberg
authors.forename: Andreas
authors.initials: A
authors.lastname: Franke
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
authors.forename: Michael
authors.initials: M
authors.lastname: Thomm
authors.forename: Michael
authors.initials: M
authors.lastname: Bartlett
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics*; D017124:Conserved Sequence; D019641:DNA, Archaeal / Q000235:genetics / Q000302:isolation & purification; D020745:Genome, Archaeal; D010442:Peptide Chain Initiation, Translational; D011401:Promoter Regions, Genetic; D020027:Pyrococcus furiosus / Q000235:genetics*; D035581:Transcription Factor TFIIB / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D019843:Archaeal Proteins; D019641:DNA, Archaeal; D035581:Transcription Factor TFIIB; C106466:transcription factor B, Archaea