title: The RNA polymerase trigger loop functions in all three phases of the transcription cycle.
abstract: The trigger loop (TL) forms a conserved element in the RNA polymerase active centre that functions in the elongation phase of transcription. Here, we show that the TL also functions in transcription initiation and termination. Using recombinant variants of RNA polymerase from Pyrococcus furiosus and a reconstituted transcription system, we demonstrate that the TL is essential for initial RNA synthesis until a complete DNA-RNA hybrid is formed. The archaeal TL is further important for transcription fidelity during nucleotide incorporation, but not for RNA cleavage during proofreading. A conserved glutamine residue in the TL binds the 2'-OH group of the nucleoside triphosphate (NTP) to discriminate NTPs from dNTPs. The TL also prevents aberrant transcription termination at non-terminator sites.
authors.affiliation: Institut of Microbiology and Archaea Center, Universität Regensburg, 93053 Regensburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fouqueau
authors.forename: Mirijam E
authors.initials: ME
authors.lastname: Zeller
authors.forename: Alan C
authors.initials: AC
authors.lastname: Cheung
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
authors.forename: Michael
authors.initials: M
authors.lastname: Thomm
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D020027:Pyrococcus furiosus / Q000201:enzymology; D012313:RNA / Q000096:biosynthesis; D059367:RNA Cleavage; D017386:Sequence Homology, Amino Acid; D061805:Transcription Elongation, Genetic; D061785:Transcription Initiation, Genetic; D061806:Transcription Termination, Genetic
chemical_list: D019843:Archaeal Proteins; D012313:RNA; D012321:DNA-Directed RNA Polymerases