Table 1.
Key enzymes, reference organisms (and accession numbers), and pathway completeness thresholds of the different CFPs.
| Autotrophic pathway | Key enzyme | Reference organism | Number of reactions in CFP | Expected completeness threshold (%) | Number of detected MAGs |
|---|---|---|---|---|---|
| rTCA1 | Citrate lyase A (ACLa)Citrate lyase B (ACLb) | Chlorobium limicola (16)(CP001097.1) | 9 | 90 | 207 |
| rTCA2 | Citryl-CoA lyase (CCL)Citryl-CoA synthetase small (CCSs)Citryl-CoA synthetase large (CCSl) | Hydrogenobacter thermophilus (18)(CP002221.1) | 12 | 73 | 10 |
| 3HP | Mesaconyl-CoA isomerase(TIGR04253) | Chloroflexus auranticus (19)(CP000909.1) | 26 | 82 | 21 |
| CBB | Phosphoribulokinase I (PRK1)Phosphoribulokinase II (PRK2) | Cereibacter(formerlyRhodobacter)sphaeroides (20)(CP001150.1) | 13 | 90 | 616 |
| HP/HB | 4-Hydroxybutyrate dehydrogenase(HBD) | Nitrosopumilus maritimus (21)(CP000866.1) | 16 | 90 | 135 |
| DC/HB | 4-Hydroxybutyrate dehydrogenase(HBD) | Ignicoccus hospitalis (22)(CP000816.1) | 14 | 75 | 18 |
Citrate is cleaved into oxalacetate (OAA) and acetyl-CoA in a one-step reaction catalyzed by ACL in rTCA1. The rTCA2 pathway is a two-step catalysis, in which citrate is first cleaved into citryl-CoA by CCS and then citryl-CoA is cleaved into OAA and acetyl-CoA.