FIGURE 5.

3-Hydroxypropionate cycle of autotrophic CO₂ fixation in the phototrophic green non-sulfur eubacterium Chloroflexus aurantiacus. Figure redrawn after reference (Alber et al., 2008). Step 1, acetyl-CoA carboxylase; step 2, malonyl-CoA reductase (bifunctional; step 3, propionyl-CoA synthase (trifunctional); step 4, propionyl-CoA carboxylase; step 5,methylmalonyl-CoA epimerase; step 6, methylmalonyl-CoA mutase; step 7, succinyl-CoA–L-malate CoA transferase; step 8, succinate dehydrogenase (electron acceptor unknown); step 9, fumarase; step 10, L-malyl-CoA/β-methylmalyl-CoA lyase (bifunctional).