TIGR01810

choline dehydrogenase; Choline dehydrogenase catalyzes the conversion of exogenously supplied choline into the intermediate glycine betaine aldehyde, as part of a two-step oxidative reaction leading to the formation of osmoprotectant betaine. This enzymatic system can be found in both gram-positive and gram-negative bacteria. As in Escherichia coli , Staphylococcus xylosus , and Sinorhizobium meliloti, this enzyme is found associated in a transciptionally co-induced gene cluster with betaine aldehyde dehydrogenase, the second catalytic enzyme in this reaction. Other gram-positive organisms have been shown to employ a different enzymatic system, utlizing a soluable choline oxidase or type III alcohol dehydrogenase instead of choline dehydrogenase. This enzyme is a member of the GMC oxidoreductase family (pfam00732 and pfam05199), sharing a common evoluntionary origin and enzymatic reaction with alcohol dehydrogenase. Outgrouping from this model, Caulobacter crescentus shares sequence homology with choline dehydrogenase, yet other genes participating in this enzymatic reaction have not currently been identified [Cellular processes, Adaptations to atypical conditions].