title: Nested DNA inversion of Campylobacter fetus S-layer genes is recA dependent.
abstract: Wild-type strains of Campylobacter fetus are covered by a monomolecular array of surface layer proteins (SLPs) critical for virulence. Each cell possesses eight SLP gene cassettes, tightly clustered in the genome, that encode SLPs of 97 to 149 kDa. Variation of SLP expression occurs by a mechanism of nested DNA rearrangement that involves the inversion of a 6.2-kb sapA promoter-containing element alone or together with one or more flanking SLP gene cassettes. The presence of extensive regions of identity flanking the 5' and 3' ends of each SLP gene cassette and of a Chi-like recognition sequence within the 5' region of identity suggests that rearrangement of SLP gene cassettes may occur by a generalized (RecA-dependent) homologous recombination pathway. To explore this possibility, we cloned C. fetus recA and created mutant strains by marker rescue, in which recA is disrupted in either S+ or S- strains. These mutants then were assessed for their abilities to alter SLP expression either in the presence or absence of a complementary shuttle plasmid harboring native recA. In contrast to all previously reported programmed DNA inversion systems, inversion in C. fetus is recA dependent.
authors.affiliation: Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: J
authors.initials: J
authors.lastname: Dworkin
authors.forename: O L
authors.initials: OL
authors.lastname: Shedd
authors.forename: M J
authors.initials: MJ
authors.lastname: Blaser
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000276:immunology; D001426:Bacterial Proteins; D001770:Blood Bactericidal Activity; D002168:Campylobacter fetus / Q000235:genetics* / Q000276:immunology; D007446:Chromosome Inversion; D003001:Cloning, Molecular; D003165:Complement System Proteins; D005798:Genes, Bacterial; D008562:Membrane Glycoproteins; D008741:Methyl Methanesulfonate; D008969:Molecular Sequence Data; D005810:Multigene Family; D009153:Mutagens; D009154:Mutation; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D009153:Mutagens; C055764:S-layer proteins; D003165:Complement System Proteins; D008741:Methyl Methanesulfonate; D011938:Rec A Recombinases