title: CtrA controls cell division and outer membrane composition of the pathogen Brucella abortus.
abstract: Brucella abortus is a pathogen infecting cattle, able to survive, traffic, and proliferate inside host cells. It belongs to the Alphaproteobacteria, a phylogenetic group comprising bacteria with free living, symbiotic, and pathogenic lifestyles. An essential regulator of cell cycle progression named CtrA was described in the model bacterium Caulobacter crescentus. This regulator is conserved in many alphaproteobacteria, but the evolution of its regulon remains elusive. Here we identified promoters that are CtrA targets using ChIP-seq and we found that CtrA binds to promoters of genes involved in cell cycle progression, in addition to numerous genes encoding outer membrane components involved in export of membrane proteins and synthesis of lipopolysaccharide. Analysis of a conditional B. abortus ctrA loss of function mutant confirmed that CtrA controls cell division. Impairment of cell division generates elongated and branched morphologies, that are also detectable inside HeLa cells. Surprisingly, abnormal bacteria are able to traffic to the endoplasmic reticulum, the usual replication niche of B. abortus in host cells. We also found that CtrA depletion affected outer membrane composition, in particular the abundance and spatial distribution of Omp25. Control of the B. abortus envelope composition by CtrA indicates the plasticity of the CtrA regulon along evolution.
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Nayla
authors.initials: N
authors.lastname: Francis
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Katy
authors.initials: K
authors.lastname: Poncin
authors.affiliation: Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS - Université de Lille, 50 Avenue Halley, Villeneuve d'Ascq, France.
authors.forename: Antonella
authors.initials: A
authors.lastname: Fioravanti
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Victoria
authors.initials: V
authors.lastname: Vassen
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Kevin
authors.initials: K
authors.lastname: Willemart
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Thi Anh Phuong
authors.initials: TA
authors.lastname: Ong
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Luca
authors.initials: L
authors.lastname: Rappez
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Letesson
authors.affiliation: Unité de Glycobiologie Structurale et Fonctionnelle, UMR 8576 CNRS - Université de Lille, 50 Avenue Halley, Villeneuve d'Ascq, France.|Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, CNRS, UMR 7283, Marseille, France.
authors.forename: Emanuele G
authors.initials: EG
authors.lastname: Biondi
authors.affiliation: Microorganisms Biology Research Unit (URBM), Narilis, University of Namur, Namur, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: De Bolle
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D001665:Binding Sites; D002003:Brucella abortus / Q000235:genetics* / Q000472:pathogenicity; D002417:Cattle; D002453:Cell Cycle / Q000235:genetics*; D002455:Cell Division / Q000235:genetics*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D010766:Phosphorylation; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D018085:Regulon; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors