Involved in the degradation of long-chain fatty acids. a long-chain fatty acid + ATP + CoA = a long-chain fatty acyl-CoA + AMP + diphosphate Lipid metabolism; fatty acid beta-oxidation. Repressed by FadR in the absence of LCFAs (fatty acids of 14-20 carbon atoms). When LCFAs are present in the medium, they are converted to long-chain acyl-CoAs, which antagonize FadR as to its binding to FadR boxes on target DNA and thus derepress transcription. Belongs to the ATP-dependent AMP-binding enzyme family.