title: Attenuated signature-tagged mutagenesis mutants of Brucella melitensis identified during the acute phase of infection in mice.
abstract: For this study, we screened 1,152 signature-tagged mutagenesis mutants of Brucella melitensis 16M in a mouse model of infection and found 36 of them to be attenuated in vivo. Molecular characterization of transposon insertion sites showed that for four mutants, the affected genes were only present in Rhizobiaceae. Another mutant contained a disruption in a gene homologous to mosA, which is involved in rhizopine biosynthesis in some strains of Rhizobium, suggesting that this sugar may be involved in Brucella pathogenicity. A mutant was disrupted in a gene homologous to fliF, a gene potentially coding for the MS ring, a basal component of the flagellar system. Surprisingly, a mutant was affected in the rpoA gene, coding for the essential alpha-subunit of the RNA polymerase. This disruption leaves a partially functional protein, impaired for the activation of virB transcription, as demonstrated by the absence of induction of the virB promoter in the Tn5::rpoA background. The results presented here highlight the fact that the ability of Brucella to induce pathogenesis shares similarities with the molecular mechanisms used by both Rhizobium and Agrobacterium to colonize their hosts.
authors.affiliation: Unité de Recherche en Biologie Moléculaire (URBM), Laboratoire d'Immunologie et de Microbiologie, University of Namur, 5000 Namur, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Lestrate
authors.forename: A
authors.initials: A
authors.lastname: Dricot
authors.forename: R-M
authors.initials: RM
authors.lastname: Delrue
authors.forename: C
authors.initials: C
authors.lastname: Lambert
authors.forename: V
authors.initials: V
authors.lastname: Martinelli
authors.forename: X
authors.initials: X
authors.lastname: De Bolle
authors.forename: J-J
authors.initials: JJ
authors.lastname: Letesson
authors.forename: A
authors.initials: A
authors.lastname: Tibor
mesh_terms: D000208:Acute Disease; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D017347:Brucella melitensis / Q000235:genetics* / Q000472:pathogenicity*; D002006:Brucellosis / Q000382:microbiology* / Q000503:physiopathology; D004251:DNA Transposable Elements; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells / Q000382:microbiology; D006801:Humans; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D016254:Mutagenesis, Insertional; D009154:Mutation; D014774:Virulence; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D037521:Virulence Factors; D012321:DNA-Directed RNA Polymerases; C113275:RNA polymerase alpha subunit