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The Aeration-Dependent Effect of Vitamin B12 on DNA Biosynthesis in Methylobacterium dichloromethanicum
Authors:Danilova  I. V.  Doronina  N. V.  Trotsenko  Yu. A.  Netrusov  A. I.  Ryzhkova (Iordan)   E. P.
Affiliation:(1) Department of Microbiology, Faculty of Biology, Moscow State University, Vorob'evy gory, Moscow, 119992, Russia;(2) Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, Pushchino, Moscow oblast, 142290, Russia
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 mgrg corrinoids per gram dry biomass, compared to about 7 mgrg/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 AdoCbl-dependent ribonucleotide reductase. In vitro studies showed that M. dichloromethanicumalso 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 conditions of poor aeration.
Keywords:Methylobacterium dichloromethanicum  ribonucleotide reductase  vitamin B12  adenosylcobalamin  DNA biosynthesis
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