3-hydroxypropionate cycle

3-Hydroxypropionate pathway is a process that allows some bacteria to generate 3-Hydroxypropionate utilizing carbon dioxide. In this pathway CO₂ is fixed (i.e. incorporated) by the action of two enzymes, acetyl-CoA carboxylase and propionyl-CoA carboxylase. These enzymes generate malonyl-CoA and (S)-methylmalonyl-CoA, respectively. Malonyl-CoA, in a series of reactions is further split into acetyl-CoA and glyoxylate. Glyoxylate is incorporated into beta-methylmalyl-coA which is then split, again through a series of reactions to release pyruvate as well as acetate, which is used to replenish the cycle. This pathway has been demonstrated in Chloroflexus, a nonsulfur photosynthetic bacterium, however other studies suggest that 3-hydroxypropionate pathway is utilized by several chemotrophic archaea.

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