title: Depression by NAD of x-ray-induced repair-type DNA synthesis in toluene-treated Bacillus subtilis.
abstract: NAD prevents a DNA repair-type synthesis that is dependent on polymerase I in toluene-treated, X-irradiated Bacillus subtilis. In unirradiated preparations, NAD had little effect on an ATP-dependent, semiconservative synthesis but partially inhibited a repair-type synthesis. In a mutant lacking polymerase I (polA1-), the presence of NAD did not affect dTTP utilization in DNA synthesis. Nicotinamide mononucleotide (NMN) partially reverses the NAD inhibition of repair-type DNA synthesis. NADP and FAD were ineffective as substitutes for NAD. Since NAD is the cofactor for polynucleotide ligase in Bacillus subtilis and NMN is known to discharge AMP from the active AMP ligase complex, it is proposed that activation of DNA ligase reduces dTMP incorporation by reducing sites for, or limiting DNA polymerase I action.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D004254:DNA Nucleotidyltransferases / Q000378:metabolism / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects*; D004269:DNA, Bacterial / Q000378:metabolism / Q000528:radiation effects*; D007700:Kinetics; D009243:NAD / Q000494:pharmacology*; D009537:Nicotinamide Mononucleotide / Q000494:pharmacology; D011830:Radiation Effects; D013997:Time Factors; D014050:Toluene / Q000494:pharmacology*
chemical_list: D004269:DNA, Bacterial; D009243:NAD; D009537:Nicotinamide Mononucleotide; D014050:Toluene; D000255:Adenosine Triphosphate; D004254:DNA Nucleotidyltransferases