Involved in the degradation of long-chain fatty acids. acetyl-CoA + an acyl-CoA = a 3-oxoacyl-CoA + CoA 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 thiolase-like superfamily. Thiolase family.