Initial steps of isethionate degradation in Cupriavidus necator H16 and Ruegeria pomeroyi DSS-3 with the corresponding gene clusters in C. necator H16 and R. pomeroyi DSS-3. CM, cytoplasmic membrane; IseJ, isethionate dehydrogenase; Xsc, sulfoacetaldehyde acetyltransferase; Pta, phosphate acetyltransferase; SDH, sulfite dehydrogenase; ThDP, thiamine diphosphate. In strain C. necator H16, where data are available, SDH is periplasmic (9).