PHENOTYPIC AND GENETIC CHARACTERISTICS OF BLEOMYCIN-SENSITIVE STRAIN OF ESCHERICHIA COLI

Abstract

Bleomycin-sensitive mutants were isolated from Escherichia coli by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. All the mutants isolated are as resistant to ultraviolet (UV) radiation as the parental strain. Genetic analysis of one of these mutants revealed that a Bleomycin-sensitive gene is located near the locus lac, i.e., in the so-called membrane cluster region. From this strain, UV-sensitive substrains were derived. Double mutants possessing Bleomycin-sensitive and recombination-deficient genes were extremely sensitive to Bleomycin but those possessing Bleomycin-sensitive and host cell-reactivation deficient genes were not. Single mutants possessing recombination-deficient gene alone were not Bleomycin sensitive. From these facts, the following possibilities are strongly suggested. (1) Bleomycin damage on DNA may be repaired by recombination function, and (2) Bleomycin-sensitive gene may enhance the permeability of the cell membrane to Bleomycin molecules.