title: Thermotoga maritima NusG: domain interaction mediates autoinhibition and thermostability.
abstract: NusG, the only universally conserved transcription factor, comprises an N- and a C-terminal domain (NTD, CTD) that are flexibly connected and move independently in Escherichia coli and other organisms. In NusG from the hyperthermophilic bacterium Thermotoga maritima (tmNusG), however, NTD and CTD interact tightly. This closed state stabilizes the CTD, but masks the binding sites for the interaction partners Rho, NusE and RNA polymerase (RNAP), suggesting that tmNusG is autoinhibited. Furthermore, tmNusG and some other bacterial NusGs have an additional domain, DII, of unknown function. Here we demonstrate that tmNusG is indeed autoinhibited and that binding to RNAP may stabilize the open conformation. We identified two interdomain salt bridges as well as Phe336 as major determinants of the domain interaction. By successive weakening of this interaction we show that after domain dissociation tmNusG-CTD can bind to Rho and NusE, similar to the Escherichia coli NusG-CTD, indicating that these interactions are conserved in bacteria. Furthermore, we show that tmNusG-DII interacts with RNAP as well as nucleic acids with a clear preference for double stranded DNA. We suggest that tmNusG-DII supports tmNusG recruitment to the transcription elongation complex and stabilizes the tmNusG:RNAP complex, a necessary adaptation to high temperatures.
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Drögemüller
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Christin
authors.initials: C
authors.lastname: Schneider
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Kristian
authors.initials: K
authors.lastname: Schweimer
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Strauß
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Birgitta M
authors.initials: BM
authors.lastname: Wöhrl
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Rösch
authors.affiliation: Lehrstuhl Biopolymere und Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany stefan.knauer@uni-bayreuth.de.
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Knauer
mesh_terms: D001665:Binding Sites; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006358:Hot Temperature; D010445:Peptide Elongation Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D017433:Protein Structure, Secondary; D012234:Rho Factor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D020124:Thermotoga maritima / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C070291:NusG protein, E coli; D010445:Peptide Elongation Factors; D012234:Rho Factor; D012269:Ribosomal Proteins; D014157:Transcription Factors; C029537:ribosomal protein S10; D004247:DNA; D012321:DNA-Directed RNA Polymerases