New recA mutations that dissociate the various RecA protein activities in Escherichia coli provide evidence for an additional role for RecA protein in UV mutagenesis

Journal Article · Mon May 01 00:00:00 EDT 1989 · J. Bacteriol.; (United States)

OSTI ID:5901838

Dutreix, M; Moreau, P L; Bailone, A; Galibert, F; Battista, J R; Walker, G C; Devoret, R

To isolate strains with new recA mutations that differentially affect RecA protein functions, we mutagenized in vitro the recA gene carried by plasmid mini-F and then introduced the mini-F-recA plasmid into a delta recA host that was lysogenic for prophage phi 80 and carried a lac duplication. By scoring prophage induction and recombination of the lac duplication, we isolated new recA mutations. A strain carrying mutation recA1734 (Arg-243 changed to Leu) was found to be deficient in phi 80 induction but proficient in recombination. The mutation rendered the host not mutable by UV, even in a lexA(Def) background. Yet, the recA1734 host became mutable upon introduction of a plasmid encoding UmuD*, the active carboxyl-terminal fragment of UmuD. Although the recA1734 mutation permits cleavage of lambda and LexA repressors, it renders the host deficient in the cleavage of phi 80 repressor and UmuD protein. Another strain carrying mutation recA1730 (Ser-117 changed to Phe) was found to be proficient in phi 80 induction but deficient in recombination. The recombination defect conferred by the mutation was partly alleviated in a cell devoid of LexA repressor, suggesting that, when amplified, RecA1730 protein is active in recombination. Since LexA protein was poorly cleaved in the recA1730 strain while phage lambda was induced, we conclude that RecA1730 protein cannot specifically mediate LexA protein cleavage. Our results show that the recA1734 and recA1730 mutations differentially affect cleavage of various substrates. The recA1730 mutation prevented UV mutagenesis, even upon introduction into the host of a plasmid encoding UmuD* and was dominant over recA+.

• Research Organization: Centre National de la Recherche Scientifique, Gif-sur-Yvette (France)
• OSTI ID: 5901838
• Journal Information: J. Bacteriol.; (United States), Vol. 171:5
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ESCHERICHIA COLI
GENETIC RADIATION EFFECTS
PROTEINS
BIOLOGICAL FUNCTIONS
ULTRAVIOLET RADIATION
MUTAGENESIS
CLEAVAGE
CLONING
DNA
DNA REPAIR
GENE RECOMBINATION
MUTATIONS
PLASMIDS
RADIOINDUCTION
STRUCTURE-ACTIVITY RELATIONSHIPS
TRANSCRIPTION
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CONSTITUENTS
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
FUNCTIONS
GENETIC EFFECTS
MICROORGANISMS
MICROSTRUCTURE
NUCLEIC ACIDS
ORGANIC COMPOUNDS
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
560130* - Radiation Effects on Microorganisms