title: [The partial recA-lexA dependence of the adaptive response of Escherichia coli to exposure to methylmethane sulfonate].
abstract: A study was made of the adaptive response to methylmethane sulfonate (MMS) in E. coli. (18 strains of B, WP2, and H/r30 groups, including three strains of bacteria with pKM101 plasmid). The adaptation of wild type cells and uvrA- and uvrB- mutants to non-lethal concentrations of MMS (10-30 mkg/ml during 90-120 min) leads to a significant increase in their resistance to lethal MMS concentrations (10-30 mM for 10-120 min): the dose modifying factor (DMF) being 1.5-1.8. In single recA or lexA mutants (or double recA uvr- and lexA uvr- mutants) the efficiency of adaptive response to MMS was significantly lower: the DMF being 1.1-1.2. In Bs-1 gamma R strain with intragenic suppressor of lexA gene the adaptive response efficiency was the same as in B/r (recA+lexA+) strain. There is no adaptive response to MMS in polA- strains. The adaptive response to MMS in E. coli is different from that to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methylnitrosourea (MNM), because in these two cases it is absolutely lexA-recA dependent. It is supposed that a partial recA-lexA dependence of the adaptive response to MMS in E. coli may be due to a specific MMS-induced lethal damage that induces an adaptive repair non-related to the system of recA-lexA-independent adaptive responses to MNNG and MNM. The presence of a plasmid of drug resistance pKM101 exerts no influence on the value, efficiency and recA-lexA-dependence of the adaptive response of E. coli to MMS.
authors.forename: V D
authors.initials: VD
authors.lastname: Zhestianikov
authors.forename: E
authors.initials: E
authors.lastname: Janovská
authors.forename: G E
authors.initials: GE
authors.lastname: Savel'eva
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects* / Q000235:genetics; D001426:Bacterial Proteins / Q000187:drug effects* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics; D005798:Genes, Bacterial / Q000187:drug effects / Q000235:genetics; D008741:Methyl Methanesulfonate / Q000494:pharmacology*; D009154:Mutation; D010957:Plasmids / Q000187:drug effects / Q000235:genetics; D011938:Rec A Recombinases / Q000187:drug effects* / Q000235:genetics; D012097:Repressor Proteins / Q000187:drug effects* / Q000235:genetics; D012697:Serine Endopeptidases; D013997:Time Factors; D014157:Transcription Factors / Q000187:drug effects*; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D008741:Methyl Methanesulfonate; D011938:Rec A Recombinases; D012097:Repressor Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein
vernacular_title: Chastichnaia recA-lexA-zavisimost' adaptivnogo otveta Escherichia coli na vozdeĭstvie metilmetansul'fonatom.