Involvement of the cgtA gene function in stimulation of DNA repair in Escherichia coli and Vibrio harveyi.
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 cgtA 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, Escherichia coli and Vibrio harveyi, the cgtA gene product enhances survival of cells after UV irradiation. Expression of the cgtA gene was found to be enhanced after UV irradiation of both E. coli and V. harveyi. Moderate overexpression of cgtA resulted in higher UV resistance of E. coli wild-type and dnaQ strains, but not in uvrA, uvrB, umuC and recA mutant hosts. Overexpression of the E. coli recA gene in the V. harveyi cgtA 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 cgtA mutant of E. coli than in the cgtA(+) strain, and contrary to wild-type bacteria, no significant increase in recA gene expression was observed after UV irradiation of this cgtA mutant. Finally, stimulation of uvrB gene transcription under these conditions was impaired in the V. harveyi cgtA mutant. All these results strongly suggest that the cgtA gene product is involved in DNA repair processes, most probably by stimulation of recA gene expression and resultant activation of RecA-dependent DNA repair pathways.
Zielke
Ryszard
R
Department of Molecular Biology, University of Gdańsk, Kładki 24, 80-822 Gdańsk, Poland.
Sikora
Aleksandra
A
Department of Molecular Biology, University of Gdańsk, Kładki 24, 80-822 Gdańsk, Poland.
Dutkiewicz
Rafał
R
Department of Molecular and Cellular Biology, Institute of Biotechnology, Intercollegiate Faculty of Biotechnology of the University of Gdańsk and Medical University of Gdańsk, Kładki 24, 80-822 Gdańsk, Poland.
Wegrzyn
Grzegorz
G
Institute of Oceanology, Polish Academy of Sciences, Św. Wojciecha 5, 81-347 Gdynia, Poland.
Czyż
Agata
A
Laboratory of Molecular Biology (affiliated with the University of Gdańsk), Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Kładki 24, 80-822 Gdańsk, Poland.
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D011836:Radiation Tolerance / Q000235:genetics; D014466:Ultraviolet Rays; D014733:Vibrio / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C058093:UvrB protein, E coli; C108621:CgtA protein, bacteria; C491572:ObgE protein, E coli; D004265:DNA Helicases; D020559:Monomeric GTP-Binding Proteins