Involved in the third cycle of side chain dehydrogenation in the beta-oxidation of cholesterol catabolism (PubMed:26161441). Contributes partly to the virulence by increasing the efficiency of beta-oxidation (PubMed:22045806, PubMed:23560677). Catalyzes the dehydrogenation of 2'-propanoyl-CoA ester side chains of 3-oxo-4-pregnene-20-carboxyl-CoA (3-OPC-CoA) to yield 3-oxo-4,17-pregnadiene-20-carboxyl-CoA (3-OPDC-CoA). Also able to dehydrogenate steroyl-CoA such as 3-oxo-chol-4-en-24-oyl-CoA (3-OCO-CoA), 1beta-(2'-propanoyl-CoA)-3a-alpha-H- 7a-beta-methylhexahydro-4-indanone (indanone-CoA ester), hexahydroindanone and pregenenone (PubMed:22045806, PubMed:23560677). 3-oxochol-4-en-22-oyl-CoA + A = 3-oxochola-4,17-dien-22-oyl-CoA + AH2 Binds 1 FAD per heterodimer. kcat is 78 min(-1) for 3-OPC-CoA as substrate (at pH 8.5 and 25 degrees Celsius) (PubMed:23560677). kcat is 5.1 min(-1) for indanone-CoA ester as substrate (at pH 8.5 and 25 degrees Celsius) (PubMed:23560677). kcat is 1.3 sec(-1) for 3-OPC-CoA as substrate (at pH 8.5 and 25 degrees Celsius) (PubMed:26161441). kcat is 0.16 sec(-1) for 3-OCO-CoA as substrate (at pH 8.5 and 25 degrees Celsius) (PubMed:26161441). Steroid metabolism; cholesterol degradation. Heterotetramer composed of FadE28 and FadE29. Induced by cholesterol and repressed by KtsR. Belongs to the acyl-CoA dehydrogenase family.