Contributes to jasmonic acid biosynthesis by initiating the beta-oxidative chain shortening of its precursors (PubMed:18267944). Acyl-coenzyme A synthetase which exhibits a high activity specifically toward OPC-6 ((9R,13R)-1a,1b-dinor-10,11-dihydro-12-oxo-15-phytoenoate) (PubMed:18267944). Also capable of activating sinapic acid, a cinnamic acid derivative (PubMed:18267944). ATP + CoA + OPC-6 = AMP + diphosphate + OPC-6-CoA kcat is 1.94 sec(-1) with OPC-6 as substrate. kcat is 0.12 sec(-1) with sinapic acid as substrate. Expressed at very low level in leaves. Both substrate-binding domains (SBD1 and SBD2) are involved in the substrate recognition, and are sufficient to confer the substrate specificity. Belongs to the ATP-dependent AMP-binding enzyme family. The predicted gene has been split into 3 genes: At1g20480, At1g20490 and At1g20500.