Catalyzes the activation of medium/long-chain fatty acids as acyl-coenzyme A (acyl-CoA), which are then transferred to the multifunctional polyketide synthase (PKS) type III for further chain extension (PubMed:15042094, PubMed:15984864, PubMed:19182784). Also involved in the degradation of cholesterol via the degradation of the side chains of C-24 branched-chain sterols. Catalyzes the ATP-dependent CoA thioesterification of the sterol 3-oxocholest-4-en-26-oate to yield 3-oxocholest-4-en-26-oyl-CoA. It can also use 3beta-hydroxy-5-cholesten-26-oate (PubMed:24244004). a medium chain fatty acid + ATP + CoA = a medium-chain fatty acyl-CoA + AMP + diphosphate a long-chain fatty acid + ATP + CoA = a long-chain fatty acyl-CoA + AMP + diphosphate (25S)-3-oxocholest-4-en-26-oate + ATP + CoA = (25S)-3-oxocholest-4-en-26-oyl-CoA + AMP + diphosphate ATP + CoA + hexanoate = AMP + diphosphate + hexanoyl-CoA ATP + CoA + octanoate = AMP + diphosphate + octanoyl-CoA ATP + CoA + decanoate = AMP + decanoyl-CoA + diphosphate ATP + CoA + dodecanoate = AMP + diphosphate + dodecanoyl-CoA ATP + CoA + tetradecanoate = AMP + diphosphate + tetradecanoyl-CoA ATP + CoA + hexadecanoate = AMP + diphosphate + hexadecanoyl-CoA ATP + CoA + octadecanoate = AMP + diphosphate + octadecanoyl-CoA 3-hydroxytetradecanoate + ATP + CoA = 3-hydroxytetradecanoyl-CoA + AMP + diphosphate 12-hydroxyoctadecanoate + ATP + CoA = 12-hydroxyoctadecanoyl-CoA + AMP + diphosphate 15-hydroxypentadecanoate + ATP + CoA = 15-hydroxypentadecanoyl-CoA + AMP + diphosphate 16-hydroxyhexadecanoate + ATP + CoA = 16-hydroxyhexadecanoyl-CoA + AMP + diphosphate 2-methylhexadecanoate + ATP + CoA = 2-methylhexadecanoyl-CoA + AMP + diphosphate 3-methylundecanoate + ATP + CoA = 3-methylundecanoyl-CoA + AMP + diphosphate 12-methyltridecanoate + ATP + CoA = 12-methyltridecanoyl-CoA + AMP + diphosphate 12-methyloctadecanoate + ATP + CoA = 12-methyloctadecanoyl-CoA + AMP + diphosphate (25S)-3beta-hydroxy-5-cholestenoate + ATP + CoA = (25S)-3beta-hydroxy-5-cholestenoyl-CoA + AMP + diphosphate kcat is 0.75 sec(-1) for 3-oxo-4-cholesten-26-oate--CoA ligase activity (at pH 7.3 and 22 degrees Celsius). Lipid metabolism; fatty acid biosynthesis. Steroid metabolism; cholesterol metabolism. Belongs to the ATP-dependent AMP-binding enzyme family.