Catalyzes the transfer of the CoA moiety from acetyl-CoA to (R)-2-hydroxyglutarate and related compounds like glutaconate. acetyl-CoA + trans-glutaconate = (2E)-glutaconyl-CoA + acetate Amino-acid degradation; L-glutamate degradation via hydroxyglutarate pathway; crotonoyl-CoA from L-glutamate: step 3/5. Heterooctamer of four A and four B subunits. Belongs to the 3-oxoacid CoA-transferase subunit A family.