title: Serum-sensitive mutation of Francisella novicida: association with an ABC transporter gene.
abstract: Francisella novicida is a facultative intracellular pathogen that can survive and grow in macrophages by preventing phagolysosomal fusion. In this study in vitro cassette mutagenesis was used to generate a library of insertion mutants of F.novicida. Two related mutants, KM14 and KM14S, initially identified as defective for growth in macrophages, were found to be sensitive to serum. These mutants were also found to grow approximately 1000-fold less well in the livers and spleens of infected mice. We cloned a genetic locus that was presumably mutagenized in these mutants and found that it included genes that had high similarity in their deduced amino acid sequence to those of msbA and orfE of Escherichia coli. The former is a member of the superfamily of ABC transporter proteins. We named the corresponding genes in F. novicida, valAB. Integration of a cloned valAB locus into the chromosome of KM14S partially restored the serum resistance phenotype found in wild-type F. novicida.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Canada.
authors.forename: K E
authors.initials: KE
authors.lastname: Mdluli
authors.forename: L S
authors.initials: LS
authors.lastname: Anthony
authors.forename: G S
authors.initials: GS
authors.lastname: Baron
authors.forename: M K
authors.initials: MK
authors.lastname: McDonald
authors.forename: S V
authors.initials: SV
authors.lastname: Myltseva
authors.forename: F E
authors.initials: FE
authors.lastname: Nano
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D005603:Francisella / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics
chemical_list: D018528:ATP-Binding Cassette Transporters; D003470:Culture Media; D004269:DNA, Bacterial