title: The anaerobe-specific orange protein complex of Desulfovibrio vulgaris hildenborough is encoded by two divergent operons coregulated by σ54 and a cognate transcriptional regulator.
abstract: Analysis of sequenced bacterial genomes revealed that the genomes encode more than 30% hypothetical and conserved hypothetical proteins of unknown function. Among proteins of unknown function that are conserved in anaerobes, some might be determinants of the anaerobic way of life. This study focuses on two divergent clusters specifically found in anaerobic microorganisms and mainly composed of genes encoding conserved hypothetical proteins. We show that the two gene clusters DVU2103-DVU2104-DVU2105 (orp2) and DVU2107-DVU2108-DVU2109 (orp1) form two divergent operons transcribed by the σ(54)-RNA polymerase. We further demonstrate that the σ(54)-dependent transcriptional regulator DVU2106, located between orp1 and orp2, collaborates with σ(54)-RNA polymerase to orchestrate the simultaneous expression of the divergent orp operons. DVU2106, whose structural gene is transcribed by the σ(70)-RNA polymerase, negatively retrocontrols its own expression. By using an endogenous pulldown strategy, we identify a physiological complex composed of DVU2103, DVU2104, DVU2105, DVU2108, and DVU2109. Interestingly, inactivation of DVU2106, which is required for orp operon transcription, induces morphological defects that are likely linked to the absence of the ORP complex. A putative role of the ORP proteins in positioning the septum during cell division is discussed.
authors.affiliation: Institut de Microbiologie de la Méditerranée, CNRS 13402 Marseille Cedex 20, France.
authors.forename: Anouchka
authors.initials: A
authors.lastname: Fiévet
authors.forename: Laetitia
authors.initials: L
authors.lastname: My
authors.forename: Eric
authors.initials: E
authors.lastname: Cascales
authors.forename: Mireille
authors.initials: M
authors.lastname: Ansaldi
authors.forename: Sofia R
authors.initials: SR
authors.lastname: Pauleta
authors.forename: Isabel
authors.initials: I
authors.lastname: Moura
authors.forename: Zorah
authors.initials: Z
authors.lastname: Dermoun
authors.forename: Christophe S
authors.initials: CS
authors.lastname: Bernard
authors.forename: Alain
authors.initials: A
authors.lastname: Dolla
authors.forename: Corinne
authors.initials: C
authors.lastname: Aubert
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D016969:Desulfovibrio vulgaris / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005810:Multigene Family; D009876:Operon; D051877:RNA Polymerase Sigma 54 / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D015534:Trans-Activators; D051877:RNA Polymerase Sigma 54