Involved in the 3-hydroxypropionate cycle used for autotrophic carbon dioxide fixation. Catalyzes the transfer of CoA moiety from succinyl-CoA to L-malate to yield L-malyl-CoA (By similarity). (S)-malate + succinyl-CoA = (S)-malyl-CoA + succinate (3S)-citramalate + succinyl-CoA = (3S)-citramalyl-CoA + succinate Forms a large complex composed of six heterodimers (alpha, beta). Under autotrophic growth conditions. Belongs to the CoA-transferase III family.