Cobalt chelatase explained
| cobalt chelatase |
| Ec Number: | 6.6.1.2 |
| Cas Number: | 81295-49-0 |
| Go Code: | 0051116 |
Cobalt chelatase is an enzyme that catalyzes the chemical reaction
ATP + hydrogenobyrinic acid a,c-diamide + Co2+ + H2O
ADP + phosphate + cob(II)yrinic acid a,c-diamide + H
+The four substrates of this enzyme are ATP, hydrogenobyrinic acid a,c-diamide, Co2+, and H2O; its four products are ADP, phosphate, cob(II)yrinic acid a,c-diamide, and H+.
The aerobic cobalt chelatase (aerobic cobalamin biosynthesis pathway)[1] [2] 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 (e.g., in Pseudomonas denitrificans) or via ATP-independent reactions of sirohydrochlorin in the anaerobic pathway (e.g., in Salmonella typhimurium).[3] [4] 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 (involved in bacteriochlorophyll synthesis, e.g., in Rhodobacter capsulatus).[4]
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 (ADP-forming). 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 (vitamin B12) in aerobic bacteria.
See also
Further reading
- Debussche L, Couder M, Thibaut D, Cameron B, Crouzet J, Blanche F . 1992 . Assay, purification, and characterization of cobaltochelatase, a unique complex enzyme catalyzing cobalt insertion in hydrogenobyrinic acid a,c-diamide during coenzyme B12 biosynthesis in Pseudomonas denitrificans . J. Bacteriol. . 174 . 7445 - 51 . 1429466 . 22 . 207441 . 10.1128/JB.174.22.7445-7451.1992 .
- Warren MJ, Raux E, Schubert HL, Escalante-Semerena JC . 2002 . The biosynthesis of adenosylcobalamin (vitamin B12) . Nat. Prod. Rep. . 19 . 390 - 412 . 12195810 . 10.1039/b108967f . 4 .
Notes and References
- Crouzet J, Cameron B, Cauchois L, Rigault S, Blanche F, Guilhot C, Levy-schil S, Rouyez MC . Genetic and sequence analyses of a Pseudomonas denitrificans DNA fragment containing two cob genes . J. Bacteriol. . 173 . 19 . 6058–6065 . 1991 . 1917840 . 208352. 10.1128/jb.173.19.6058-6065.1991 .
- Crouzet J, Cameron B, Blanche F, Thibaut D, Debussche L, Couder M . Assay, purification, and characterization of cobaltochelatase, a unique complex enzyme catalyzing cobalt insertion in hydrogenobyrinic acid a,c-diamide during coenzyme B12 biosynthesis in Pseudomonas denitrificans . J. Bacteriol. . 174 . 22 . 7445–7451 . 1992 . 1429466 . 207441. 10.1128/jb.174.22.7445-7451.1992 .
- Roth JR, Lawrence JG, Bobik TA . Cobalamin (coenzyme B12): synthesis and biological significance . Annu. Rev. Microbiol. . 50 . 137–181 . 1996 . 8905078 . 10.1146/annurev.micro.50.1.137. 36290299 . https://web.archive.org/web/20190307012130/http://pdfs.semanticscholar.org/d859/d9a7b8f4dcebb41a5992232b36cf2f4351d5.pdf . dead . 2019-03-07 .
- Willows RD, Al-Karadaghi S, Hansson M, Fodje MN, Hansson A, Olsen JG, Gough S . Interplay between an AAA module and an integrin I domain may regulate the function of magnesium chelatase . J. Mol. Biol. . 311 . 1 . 111–122 . 2001 . 11469861 . 10.1006/jmbi.2001.4834.
