3-hydroxypropionate bicycle

Edge evidence

• hydrogencarbonate fixed by 3-hydroxypropionate bicycle METPO:2007404

  Two molecules of bicarbonate are fixed per cycle turn.

  • DOI:10.1128/AEM.02473-10 Berg describes the 3-hydroxypropionate bicycle in Chloroflexus.
• 3-hydroxypropionate bicycle contributes to carbon fixation RO:0002326

  The bicycle is one of the recognized autotrophic CO2-fixation pathways.

  • DOI:10.1146/annurev-marine-120709-142712 Hügler & Sievert include the 3-hydroxypropionate pathway among autotrophic carbon-fixation strategies.
• acetyl-CoA carboxylase causally upstream of malonyl-CoA

  Acetyl-CoA carboxylase converts acetyl-CoA and bicarbonate to malonyl-CoA at the expense of ATP.

  • DOI:10.17192/z2022.0467 acetyl-CoA carboxylase (EC 6.4.1.2) converts acetyl-CoA and bicarbonate to malonyl-CoA.
• propionyl-CoA carboxylase causally upstream of (2S)-methylmalonyl-CoA

  Propionyl-CoA carboxylase converts propionyl-CoA and bicarbonate to (2S)-methylmalonyl-CoA at the expense of ATP.

  • DOI:10.17192/z2022.0467 propionyl-CoA carboxylase (EC 6.4.1.3) converts propionyl-CoA and bicarbonate to (2S)-methylmalonyl-CoA.
• malonyl-CoA reductase causally upstream of 3-hydroxypropionate

  Malonyl-CoA reductase reduces malonyl-CoA to 3-hydroxypropionate; central diagnostic enzyme.

  • DOI:10.1146/annurev-marine-120709-142712 malonyl-CoA reductase reducing malonyl-CoA to 3-hydroxypropionate.
• propionyl-CoA synthase causally upstream of propionyl-CoA

  Propionyl-CoA synthase converts 3-hydroxypropionate to propionyl-CoA.

  • DOI:10.1146/annurev-marine-120709-142712 propionyl-CoA synthase converting 3-hydroxypropionate to propionyl-CoA.
• MMC lyase causally upstream of pyruvate

  MMC lyase cleaves citramalyl-CoA to pyruvate and acetyl-CoA.

  • DOI:10.1146/annurev-marine-120709-142712 cleavage of citramalyl-CoA to pyruvate and acetyl-CoA.
• MMC lyase causally upstream of acetyl-CoA

  MMC lyase cleavage also yields acetyl-CoA alongside pyruvate.

  • DOI:10.1146/annurev-marine-120709-142712 cleavage of citramalyl-CoA to pyruvate and acetyl-CoA.
• 3-hydroxypropionate bicycle has output pyruvate

  Overall the bicycle produces one pyruvate from three bicarbonates.

  • DOI:10.1146/annurev-marine-120709-142712 producing one pyruvate from three bicarbonates.