Uracil-DNA glycosylase activities in hyperthermophilic micro-organisms.

Hyperthermophiles exist in conditions which present an increased threat to the informational integrity of their DNA, particularly by hydrolytic damage. As in mesophilic organisms, specific activities must exist to restore and protect this template function of DNA. In this study we have demonstrated the presence of thermally stable uracil-DNA glycosylase activities in seven hyperthermophiles; one bacterial: Thermotoga maritima, and six archaeal: Sulfolobus solfataricus, Sulfolobus shibatae, Sulfolobus acidocaldarius, Thermococcus litoralis, Pyrococcus furiosus and Pyrobaculum islandicum. Uracil-DNA glycosylase inhibitor protein of the Bacillus subtilis bacteriophage PBS1 shows activity against all of these, suggesting a highly conserved tertiary structure between hyperthermophilic and mesophilic uracil-DNA glycosylases.