Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D03345 (beta-Galactosidase)
 434 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

beta-Galactosidase activities (beta-GA) of E. coli strains carrying the fusion gene of recA and lacZ, GE94 and its DNA repair-deficient derivatives such as KY946[uvrA], KY945[recA] and KY943[lexA] treated with UV, 4NQO, MNNG and MMC were examined. The beta-GA, reflecting the SOS-inducing activity, of GE94 and KY946 treated with these compounds increased significantly with a clear dose-response relationship, and reached a maximum level within 60 min, while no response was seen in KY945 and KY943. Using KY946 and KY945 as a positive and a negative indicator, respectively, the SOS-inducing activity of oxidative mutagens, i.e., hydrogen peroxide (H2O2), formaldehyde, tert-butyl hydroperoxide, cumene hydroperoxide and streptonigrin, was investigated. Clear dose-dependent increases in beta-GA were observed in KY946 treated with all oxidative mutagens tested, but not in KY945. Significant increases in beta-GA were observed with a lower concentration of H2O2 and a shorter incubation time of 4NQO in this assay than in the umu-test. The assay, called 'Rec-lac test' by us, may be useful to detect environmental genotoxic substances.
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PMID:'Rec-lac test' for detecting SOS-inducing activity of environmental genotoxic substance. 189 67

Clones encoding the recA gene of Agrobacterium tumefaciens C58 were isolated from a cosmid bank by complementation of an Escherichia coli recA mutation. Subcloning and mutagenesis with the lacZ fusion transposon Tn3HoHo1 located the Agrobacterium recA gene to a 1.3-kilobase segment of DNA. beta-Galactosidase expression from the fusions established the direction in which the gene was transcribed. The gene restored homologous recombination as well as DNA repair functions in E. coli recA mutants. Similar complementation of DNA repair functions was observed in the UV-induced Rec- Agrobacterium mutant, LBA4301. The Agrobacterium recA gene was disrupted by insertion of a cassette encoding resistance to erythromycin, and the mutated gene was marker exchanged into the chromosome of strain NT-1. The resulting strain, called UIA143, was sensitive to UV irradiation and methanesulfonic acid methyl ester and unable to carry out homologous recombination functions. The mutation was stable and had no effect on other genetic properties of the Agrobacterium strain, including transformability and proficiency as a conjugal donor or recipient. Furthermore, strain UIA143 became tumorigenic upon introduction of a Ti plasmid, indicating that tumor induction is independent of recA functions. Sequence homology was detected between the recA genes of strain C58 and E. coli as well as with DNA isolated from agrobacteria representing the three major biochemically differentiated biovars of this genus. In some cases, biovar-specific restriction fragment length polymorphisms were apparent at the recA locus.
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PMID:Construction of an Agrobacterium tumefaciens C58 recA mutant. 267 71