Repression of damage-inducible (din) genes by the lexA3 mutation or by plasmid carrying the lexA gene; effect on pyrimidine dimer excision in UV-irradiated Escherichia coli.
Dimer excision was followed in Escherichia coli K-12 AB1157 DM49 lexA3 mutant (whose repressor is not cleavable with RecA protease), and in E. coli K-12 AB2497[pGC3] carrying the cloned lexA gene. In either case din genes could not be efficiently derepressed. In such cells ultraviolet (UV) irradiation caused an extensive DNA degradation, which was not observed in cells with derepressed din genes. Even after a high UV dose (70 J/m2) dimers were being excised efficiently. However, progressive DNA degradation interfered with the precise detection of unexcised dimers. We conclude that induction of din genes is required for filling some of the gaps and for prevention of DNA degradation, but not for excision itself.
Masek
F
F
Department of Molecular Genetics, Slovak Academy of Sciences, Bratislava, Czechoslavakia.
Skorvaga
M
M
Sedliaková
M
M
D001426:Bacterial Proteins / Q000235:genetics*; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000528:radiation effects; D005809:Genes, Regulator; D009154:Mutation; D010957:Plasmids; D011740:Pyrimidine Dimers / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics*; D012697:Serine Endopeptidases; D014157:Transcription Factors / Q000235:genetics*; D014466:Ultraviolet Rays; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011740:Pyrimidine Dimers; D012097:Repressor Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein