Substitution of Co alpha-(5-hydroxybenzimidazolyl)cobamide (factor III) by vitamin B12 in Methanobacterium thermoautotrophicum.

摘要: Methanobacterium thermoautotrophicum grown on mineral medium contains 120 nmol of Co alpha-(5-hydroxybenzimidazolyl)cobamides (derivatives factor III) per g dry cell mass as the sole cobamide. The bacterium assimilated several corrinoids and benzimidazole bases during autotrophic growth. were converted into III; however, after three transfers in 5,6-dimethylbenzimidazole (200 microM)-supplemented medium, derivatives III completely replaced by vitamin B12, which is atypical for methanogens. total cobamide content these cells their growth rate not affected compared with III-containing cells. Therefore, high rather than a particular type required metabolism Derivatives are essential cofactors cobamide-containing enzymes from methanogenic bacteria, but they result unique biosynthetic ability archaebacteria. biosynthesis include unspecific enzymes, made it possible either to convert non-species-derived or synthesize other types cobamides III. regulated its end product. In addition, uptake extracellular controlled, regulate cellular biosynthesis.