Involved in the biosynthesis of prenylated phenolics natural products which contribute to the bitter taste of beer and display broad biological activities (Probable). Catalyzes the ligation of CoA on isovalerate to produce 3-methylbutanoyl-CoA (PubMed:23300257). Can also use butanoate, hexanoate, pentanoate, 3-methylpentanoate and 4-methylpentanoate as substrates with a lower efficiency (PubMed:23300257). ATP + CoA + isovalerate = 3-methylbutanoyl-CoA + AMP + diphosphate ATP + butanoate + CoA = AMP + butanoyl-CoA + diphosphate ATP + CoA + hexanoate = AMP + diphosphate + hexanoyl-CoA ATP + CoA + pentanoate = AMP + diphosphate + pentanoyl-CoA 3-methylpentanoate + ATP + CoA = 3-methylpentanoyl-CoA + AMP + diphosphate 4-methylpentanoate + ATP + CoA = 4-methylpentanoyl-CoA + AMP + diphosphate kcat is 17.2 min(-1) with isovalerate as substrate (PubMed:23300257). kcat is 23.3 min(-1) with CoA as substrate (PubMed:23300257). Secondary metabolite biosynthesis. Restricted to glandular trichomes (lupulin glands). Accumulates progressively in glandular trichomes (lupulin glands) after flowering. 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.