Cobalt chelatase
Cobalt chelatase is an enzyme that catalyzes the chemical reaction
The four substrates of this enzyme are ATP, hydrogenobyrinic acid a,c-diamide, Co2+, and H2O; its four products are ADP, phosphate, cobyrinic acid a,c-diamide, and H+.
The aerobic cobalt chelatase consists of three subunits, CobT, CobN and CobS.
The macrocycle of vitamin B12 can be complexed with metal via the ATP-dependent reactions in the aerobic pathway or via ATP-independent reactions of sirohydrochlorin in the anaerobic pathway. The corresponding cobalt chelatases are not homologous. However, aerobic cobalt chelatase subunits CobN and CobS are homologous to Mg-chelatase subunits BchH and BchI, respectively. CobT, too, has been found to be remotely related to the third subunit of Mg-chelatase, BchD.
This enzyme belongs to the family of ligases, specifically those forming nitrogen-D-metal bonds in coordination complexes. The systematic name of this enzyme class is hydrogenobyrinic-acid-a,c-diamide:cobalt cobalt-ligase . Other names in common use include hydrogenobyrinic acid a,c-diamide cobaltochelatase, CobNST, and CobNCobST. This enzyme is part of the biosynthetic pathway to cobalamin in aerobic bacteria.
