title: rexAB mutants in Streptococcus pneumoniae.
abstract: Streptococcus pneumoniae is a human pathogen that is naturally transformable. In this study a major component of the homologous recombination pathway, the RexAB exonuclease/helicase, was characterized. rexA and rexB insertional mutants were constructed using mariner mutagenesis and found to have identical phenotypes. Both rexAB mutants displayed poor cell viability, reduced double-strand exonuclease activity, UV sensitivity and a reduced level of gene conversion compared to the wild-type strain. No effect was observed on plasmid and chromosomal transformation efficiencies. These results indicate that in S. pneumoniae, RexAB is required for DNA repair, but not for chromosomal transformation and plasmid establishment.
authors.affiliation: Unité de Recherches Laitières et Génétique Appliquée, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas, France.
authors.forename: David
authors.initials: D
authors.lastname: Halpern
authors.affiliation: Unité de Recherches Laitières et Génétique Appliquée, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas, France.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gruss
authors.affiliation: Laboratoire de Microbiologie et Génétique Moléculaires UMR 5100, CNRS Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Claverys
authors.affiliation: Unité de Recherches Laitières et Génétique Appliquée, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas, France.
authors.forename: Meriem El
authors.initials: ME
authors.lastname: Karoui
mesh_terms: D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D009154:Mutation; D010957:Plasmids; D011995:Recombination, Genetic; D013296:Streptococcus pneumoniae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development*; D014466:Ultraviolet Rays
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D005090:Exodeoxyribonucleases; D004265:DNA Helicases