title: recA gene involvement in oxidative and thermal stress in Lactococcus lactis.
abstract: The recA gene is best known for its effects on homologous recombination and DNA repair via SOS induction. There is gathering evidence that recA also affects expression of genes associated with different types of stress. We studied recA properties in Lactococcus lactis by generating a recA-disrupted mutant of MG1363 and comparing it with the wild type strain. recA appears to have an important role in cell survival upon oxygen or thermal stress, in addition to its conserved role in DNA repair. Oxygen toxicity appears to be due to the production of hydroxyl radicals via the Fenton reaction; recA would be involved in the repair of DNA damage generated by these radicals. Surprisingly, the recA strain stops growing at elevated temperature (37 degrees C). Immunological tests indicate that amounts of three heat shock proteins are reduced in the recA strain compared to the wild type strain. In contrast, the amount of heat shock regulator HflB is markedly increased, even at low temperature. HflB is known to degrade heat shock transcription factor sigma 32 in Escherichia coli. We propose that heat shock response is reduced in the recA mutant due to overproduction of HflB.
authors.affiliation: Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique Jouy-en-Josas, France.
authors.forename: P
authors.initials: P
authors.lastname: Duwat
authors.forename: S
authors.initials: S
authors.lastname: Sourice
authors.forename: S D
authors.initials: SD
authors.lastname: Ehrlich
authors.forename: A
authors.initials: A
authors.lastname: Gruss
mesh_terms: D049069:ATP-Dependent Proteases; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D004260:DNA Repair / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D006358:Hot Temperature; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics*; D011995:Recombination, Genetic; D013014:SOS Response, Genetics; D012808:Sigma Factor / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012808:Sigma Factor; D011938:Rec A Recombinases; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli