1887

Abstract

CgtA is a member of the Obg/Gtp1 subfamily of small GTP-binding proteins. CgtA homologues have been found in various prokaryotic and eukaryotic organisms, ranging from bacteria to humans. Nevertheless, despite the fact that is an essential gene in most bacterial species, its function in the regulation of cellular processes is largely unknown. Here it has been demonstrated that in two bacterial species, and , the gene product enhances survival of cells after UV irradiation. Expression of the gene was found to be enhanced after UV irradiation of both and . Moderate overexpression of resulted in higher UV resistance of wild-type and strains, but not in , , and mutant hosts. Overexpression of the gene in the mutant, which is very sensitive to UV light, restored the level of survival of UV-irradiated cells to the levels observed for wild-type bacteria. Moreover, the basal level of the RecA protein was lower in a temperature-sensitive mutant of than in the strain, and contrary to wild-type bacteria, no significant increase in gene expression was observed after UV irradiation of this mutant. Finally, stimulation of gene transcription under these conditions was impaired in the mutant. All these results strongly suggest that the gene product is involved in DNA repair processes, most probably by stimulation of gene expression and resultant activation of RecA-dependent DNA repair pathways.

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2003-07-01
2024-05-01
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