Effect of a corrinoid on <Emphasis Type="Italic">Methanosarcina barkeri</Emphasis> DNA synthesis |
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Authors: | E P Ryzhkova A L Brukhanov |
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Institution: | (1) Department of Microbiology, Moscow State University, Moscow, Russia |
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Abstract: | Methanosarcina barkeri is capable of synthesizing large amounts of corrinoids, compounds of the vitamin B12 group, although not cobalamin. In the present work, exogenous cobalamin was demonstrated to upregulate DNA synthesis in M. barkeri cell suspensions incubated under air. The effect is similar to the one in Propionibacterium freudenreichii cells, though less pronounced. The growth of the archaeon under anaerobic conditions was shown to be suppressed by cobalamin and 5,6-dimethylbenzimidazole. The data obtained suggest the presence of a corrinoid-dependent ribonucleotide reductase in the archaeal cells which provides for deoxyribose precursors for DNA biosynthesis independently of the presence of molecular oxygen in the medium. Growth suppression under anoxic conditions by cobalamin and 5,6-dimethylbenzimidazole may be due to a decrease in the concentration of factor III, a polyfunctional corrinoid dominating in M. barkeri cells. |
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Keywords: | Methanosarcina barkeri Propionibacterium freudenreichii DNA biosynthesis corrinoids factor III cobalamin adenosylcobalamin ribonucleotide reductase |
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