Functions in the bile acid 7alpha-dehydroxylation pathway, which forms secondary bile acids via the 7alpha-dehydroxylation of primary bile acids, and is carried out by intestinal anaerobic bacteria. Acts as a bile acid CoA transferase with broad bile acid substrate specificity. Catalyzes the transfer of the CoA moiety of secondary bile acid-CoA compounds to primary bile acids. Can use lithocholoyl-CoA, deoxycholoyl-CoA and allodeoxycholoyl-CoA as bile acid CoA donors and cholate, allocholate, chenodeoxycholate, ursodeoxycholate, and beta-muricholate as bile acid CoA acceptors (PubMed:22021638). Also displays CoA hydrolase activity, being able to catalyze the hydrolysis of choloyl-CoA, 3-dehydrocholoyl-CoA, and chenodeoxycholoyl-CoA, releasing CoA and the corresponding free bile acid (PubMed:9869646). However, this latter activity may not represent the actual activity of this enzyme, since using a transferase rather than hydrolase, the bacteria conserve the thioester bond energy, saving ATP molecules (Probable). Shows no hydrolytic activity with acetyl-CoA, isovaleryl-CoA, palmitoyl-CoA, or phenylacetyl-CoA as substrates (PubMed:9869646). cholate + lithocholoyl-CoA = choloyl-CoA + lithocholate cholate + deoxycholoyl-CoA = choloyl-CoA + deoxycholate allodeoxycholoyl-CoA + cholate = allodeoxycholate + choloyl-CoA allocholate + deoxycholoyl-CoA = allocholoyl-CoA + deoxycholate allocholate + lithocholoyl-CoA = allocholoyl-CoA + lithocholate allocholate + allodeoxycholoyl-CoA = allocholoyl-CoA + allodeoxycholate chenodeoxycholate + lithocholoyl-CoA = chenodeoxycholoyl-CoA + lithocholate deoxycholoyl-CoA + ursodeoxycholate = deoxycholate + ursodeoxycholoyl-CoA lithocholoyl-CoA + ursodeoxycholate = lithocholate + ursodeoxycholoyl-CoA allodeoxycholoyl-CoA + ursodeoxycholate = allodeoxycholate + ursodeoxycholoyl-CoA beta-muricholate + lithocholoyl-CoA = beta-muricholoyl-CoA + lithocholate beta-muricholate + deoxycholoyl-CoA = beta-muricholoyl-CoA + deoxycholate allodeoxycholoyl-CoA + beta-muricholate = allodeoxycholate + beta-muricholoyl-CoA choloyl-CoA + H2O = cholate + CoA + H(+) chenodeoxycholoyl-CoA + H2O = chenodeoxycholate + CoA + H(+) Optimum pH is between pH 6.0 and 7.0 or the hydrolysis of choloyl-CoA. No activity is detected below pH 4.0 or above pH 9.0. Lipid metabolism; bile acid biosynthesis. Induced by bile acids. Belongs to the CoA-transferase III family.