Fig. 9.

Proposed degradation pathway of DTDP. Initial cleavage by a dihydrolipoamide dehydrogenase (step I) yields two molecules of 3MP, which are further oxygenated by a dioxygenase (step II), yielding 3SP. The latter is activated to the corresponding CoA thioester by SucCD (step III), as shown in the present study. The next step is most probably the dehydrogenation of 3-sulfinopropionyl-CoA by an acyl-CoA-dehydrogenase homologue (step IV) in an FAD-dependent step. The sulfur moiety of the dehydrogenation product, 3-sulfino-2,3-dehydropropionyl-CoA, is putatively removed by an enzymatic or an autocatalytic reaction. Propionyl-CoA subsequently enters the central metabolism via the methyl citric acid cycle.