InterPro: IPR011533 Choline dehydrogenase

Choline dehydrogenase catalyses 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 [1], Staphylococcus xylosus [2], and Rhizobium meliloti (Sinorhizobium meliloti) [3], this enzyme is found associated in a transcriptionally 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, utilising a soluble choline oxidase or type III alcohol dehydrogenase instead of choline dehydrogenase [4]. This enzyme is a member of the GMC oxidoreductase family, sharing a common evolutionary origin and enzymatic reaction with alcohol dehydrogenase [5]. Out grouping from this model, Caulobacter crescentus (Caulobacter vibrioides) shares sequence homology with choline dehydrogenase, yet other genes participating in this enzymatic reaction have not currently been identified.