Isolation and analysis of a mutant of Escherichia coli hyper-resistant to near-ultraviolet light plus 8-methoxypsoralen.
A mutant of Escherichia coli K12 was isolated which shows enhanced resistance towards near-ultraviolet (NUV) light plus 8-methoxypsoralen (MPS) compared with its wild-type parent strain. The PUVA (NUV + MPS)-resistant strain remains as sensitive for far-ultraviolet (FUV) light as its parent strain. A recA- derivative of this mutant strain was as sensitive to PUVA as its reca- parental strain. A polyacrylamide gel electrophoresis study of total cell lysates from the mutant bacteria showed that a protein of approximately 55 kd was synthesised in higher concentrations compared with its synthesis in the wild-type parent strain. Furthermore, synthesis of this protein was reduced in the recA- derivative of the mutant strain suggesting that the recA gene product might be acting as a regulator of the synthesis of the 55-kd protein. It is suggested that in E. coli damage to DNA by PUVA can be repaired by a specific RecA LexA-inducible repair system and the repair efficiency is enhanced if the 55-kd protein is present in concentrations higher than that synthesised by the wild-type parent E. coli.
D001426:Bacterial Proteins / Q000235:genetics; D004260:DNA Repair; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D008730:Methoxsalen / Q000633:toxicity*; D009154:Mutation / Q000187:drug effects / Q000528:radiation effects; D011938:Rec A Recombinases / Q000235:genetics; D012697:Serine Endopeptidases; D014466:Ultraviolet Rays; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D008730:Methoxsalen; D011938:Rec A Recombinases; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein