The fate of thymine-containing dimers in ultraviolet-irradiated Halobacterium cutirubrum.
Extremely halophilic bacteria do not recover in the dark from the effects of ultraviolet radiation, although they can be completely photoreactivated, thus proving that pyrimidine dimers are the cytotoxic photoproducts. We have now shown, by studying the fate of thymine-containing dimers during dark liquid-holding of Halobacterium cutirubrum, that the lack of dark repair in these bacteria is due to their inability to excise such lesions, in contrast to Escherichia coli B. Nevertheless, extensive nonspecific degradation of DNA occurs in H. cutirubrum following ultraviolet irradiation, so the lack of dimer excision is not due to a generalised inability to degrade DNA after such treatment. These findings raise interesting questions concerning the basis of the resistance of halophiles to ultraviolet radiation.
Fitt
P S
PS
Department of Biochemistry, University of Ottawa, Canada.
Sharma
N
N
D004260:DNA Repair; D004269:DNA, Bacterial / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000235:genetics / Q000528:radiation effects; D006217:Halobacterium / Q000235:genetics / Q000528:radiation effects*; D011740:Pyrimidine Dimers / Q000528:radiation effects*; D013045:Species Specificity; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D011740:Pyrimidine Dimers