CoA transferase having broad substrate specificity for short-chain acyl-CoA thioesters with the activity decreasing when the length of the carboxylic acid chain exceeds four carbons. May play a role in short-chain fatty acid metabolism in E.coli. acetate + an acyl-CoA = a carboxylate + acetyl-CoA Homotetramer; dimer of dimers. Formation of the covalent enzyme-CoA thioester intermediate proceeds via an unstable anhydride species formed between the carboxylate group of the catalytic glutamate of the enzyme and the carbonyl carbon of the thioester linkage of the substrate. Belongs to the 3-oxoacid CoA-transferase family.