title: Partial disruption of translational and posttranslational machinery reshapes growth rates of Bartonella birtlesii.
abstract: Specialization of bacteria in a new niche is associated with genome repertoire changes, and speciation in bacterial specialists is associated with genome reduction. Here, we tested a signature-tagged mutant library of 3,456 Bartonella birtlesii clones to detect mutants that could grow rapidly in vitro. Overall, we found 124 mutants that grew faster than the parental wild-type strain in vitro. We sequenced the genomes of the four mutants with the most rapid growth (formed visible colonies in only 1 to 2 days compared with 5 days for the wild type) and compared them to the parental isolate genome. We found that the number of disrupted genes associated with translation in the 124 rapid-growth clones was significantly higher than the number of genes involved in translation in the full genome (P < 10(-6)). Analysis of transposon integration in the genome of the four most rapidly growing clones revealed that one clone lacked one of the two wild-type RNA ribosomal operons. Finally, one of the four clones did not induce bacteremia in our mouse model, whereas infection with the other three resulted in a significantly lower bacterial count in blood than that with the wild-type strain.
  
  
  OBJECTIVE
  Here, we show that specialization in a specific niche could be caused by the disruption of critical genes. Most of these genes were involved in translation, and we show that evolution of obligate parasitism bacteria was specifically associated with disruption of translation system-encoding genes.
authors.affiliation: URMITE CNRS-IRD, URMITE 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille Université, Marseille, France.
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Rolain
authors.forename: Muriel
authors.initials: M
authors.lastname: Vayssier-Taussat
authors.forename: Watcharee
authors.initials: W
authors.lastname: Saisongkorh
authors.forename: Vicky
authors.initials: V
authors.lastname: Merhej
authors.forename: Gregory
authors.initials: G
authors.lastname: Gimenez
authors.forename: Catherine
authors.initials: C
authors.lastname: Robert
authors.forename: Danielle
authors.initials: D
authors.lastname: Le Rhun
authors.forename: Christoph
authors.initials: C
authors.lastname: Dehio
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
mesh_terms: D000818:Animals; D001473:Bartonella / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D004251:DNA Transposable Elements; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D051379:Mice; D008807:Mice, Inbred BALB C; D016254:Mutagenesis, Insertional; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D017422:Sequence Analysis, DNA
chemical_list: D004251:DNA Transposable Elements