title: [The aeration-dependent effect of vitamin B12 on DNA biosynthesis in Methylobacterium dichloromethanicum].
abstract: The effect of vitamin B12 (cobalamin) on DNA biosynthesis in Methylobacterium dichloromethanicum was studied. When cultivated in media with methanol or dichloromethane, the bacterium produced approximately 10 micrograms corrinoids per g dry biomass, compared to about 7 micrograms/g when cultivated on ethanol or succinate. Exogenous adenosylcobalamin (AdoCbl) stimulated DNA biosynthesis in M. dichloromethanicum cells grown under poor aeration, the effect being mediated by AdoCb1-linked ribonucleotide reductase. In vitro studies showed that M. dichloromethanicum also has AdoCbl-independent ribonucleotide reductase. Under good aeration, exogenous AdoCbl had no effect on DNA biosynthesis, while hydroxyurea suppressed it. These data suggest that AdoCbl-independent ribonucleotide reductase, which is likely to be activated by oxygen, plays an important part in DNA biosynthesis when M. dichloromethanicum is cultured with good aeration, whereas AdoCbl-dependent ribonucleotide reductase is active under the conditions of poor aeration.
authors.affiliation: Department of Microbiology, Faculty of Biology, Moscow State University, Vorob'evy gory, Moscow, 119992 Russia.
authors.forename: I V
authors.initials: IV
authors.lastname: Danilova
authors.forename: N V
authors.initials: NV
authors.lastname: Doronina
authors.forename: Iu A
authors.initials: IuA
authors.lastname: Trotsenko
authors.forename: A I
authors.initials: AI
authors.lastname: Netrusov
authors.forename: E P
authors.initials: EP
authors.lastname: Ryzhkova
mesh_terms: D000332:Aerobiosis; D003038:Cobamides / Q000494:pharmacology; D003470:Culture Media; D004269:DNA, Bacterial / Q000096:biosynthesis*; D000432:Methanol / Q000378:metabolism; D008752:Methylene Chloride / Q000378:metabolism; D020580:Methylobacterium / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D012264:Ribonucleotide Reductases / Q000378:metabolism; D014805:Vitamin B 12 / Q000096:biosynthesis / Q000494:pharmacology*
chemical_list: D003038:Cobamides; D003470:Culture Media; D004269:DNA, Bacterial; D008752:Methylene Chloride; D012264:Ribonucleotide Reductases; C000913:cobamamide; D014805:Vitamin B 12; D000432:Methanol