View source for Cobalt chelatase

{{Short description|Enzyme}}
{{infobox enzyme
| Name       = cobalt chelatase
| EC_number  = 6.6.1.2
| CAS_number = 81295-49-0
| GO_code    = 0051116
| image      = EVWong CC2XVX raytraced.png
| caption    = Putative cobalt chelatase monomer from ''Desulvobrio vulgaris''.<ref>{{cite journal |last1=Romão |first1=Célia V. |last2=Ladakis |first2=Dimitrios |last3=Lobo |first3=Susana A. L. |last4=Carrondo |first4=Maria A. |last5=Brindley |first5=Amanda A. |last6=Deery |first6=Evelyne |last7=Matias |first7=Pedro M. |last8=Pickersgill |first8=Richard W. |last9=Saraiva |first9=Lígia M. |last10=Warren |first10=Martin J. |title=Evolution in a family of chelatases facilitated by the introduction of active site asymmetry and protein oligomerization |journal=Proceedings of the National Academy of Sciences |date=4 January 2011 |volume=108 |issue=1 |pages=97–102 |doi=10.1073/pnas.1014298108 |pmid=21173279 |pmc=3017170 |doi-access=free }}</ref>
}}
{{Pfam box |Symbol = CobT |Name = Cobalt chelatase, CobT subunit |Pfam = PF06213 |InterPro = IPR006538 |PROSITE =  |PDB = }}

'''Cobalt chelatase''' ({{EnzExplorer|6.6.1.2}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]

:ATP + hydrogenobyrinic acid a,c-diamide + Co<sup>2+</sup> + H<sub>2</sub>O <math>\rightleftharpoons</math> ADP + phosphate + cob(II)yrinic acid a,c-diamide + H<sup>+</sup>

The four [[substrate (biochemistry)|substrates]] of this enzyme are [[adenosine triphosphate|ATP]], [[hydrogenobyrinic acid a,c-diamide]], [[Cobalt|Co]]<sup>2+</sup>, and [[water|H<sub>2</sub>O]]; its four [[product (chemistry)|products]] are [[adenosine diphosphate|ADP]], [[phosphate]], [[cob(II)yrinic acid a,c-diamide]], and [[hydrogen ion|H<sup>+</sup>]].

The aerobic cobalt chelatase (aerobic cobalamin biosynthesis pathway)<ref name="PUB00011188">{{cite journal |vauthors=Crouzet J, Cameron B, Cauchois L, Rigault S, Blanche F, Guilhot C, Levy-schil S, Rouyez MC |title=Genetic and sequence analyses of a Pseudomonas denitrificans DNA fragment containing two cob genes |journal=J. Bacteriol. |volume=173 |issue=19 |pages=6058–6065 |year=1991 |pmid=1917840 |pmc=208352|doi=10.1128/jb.173.19.6058-6065.1991 }}</ref><ref name="PUB00009664">{{cite journal |vauthors=Crouzet J, Cameron B, Blanche F, Thibaut D, Debussche L, Couder M |title=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 |journal=J. Bacteriol. |volume=174 |issue=22 |pages=7445–7451 |year=1992 |pmid=1429466 |pmc=207441|doi=10.1128/jb.174.22.7445-7451.1992 }}</ref> consists of three subunits, CobT, CobN ({{InterPro|IPR003672}}) and CobS ({{InterPro|IPR006537}}).

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]]'').<ref name="PUB00006361">{{cite journal |vauthors=Roth JR, Lawrence JG, Bobik TA |title=Cobalamin (coenzyme B12): synthesis and biological significance |journal=Annu. Rev. Microbiol. |volume=50 |pages=137–181 |year=1996 |pmid=8905078 |doi=10.1146/annurev.micro.50.1.137|s2cid=36290299 |url=http://pdfs.semanticscholar.org/d859/d9a7b8f4dcebb41a5992232b36cf2f4351d5.pdf |archive-url=https://web.archive.org/web/20190307012130/http://pdfs.semanticscholar.org/d859/d9a7b8f4dcebb41a5992232b36cf2f4351d5.pdf |url-status=dead |archive-date=2019-03-07 }}</ref><ref name="PUB00011189">{{cite journal |vauthors=Willows RD, Al-Karadaghi S, Hansson M, Fodje MN, Hansson A, Olsen JG, Gough S |title=Interplay between an AAA module and an integrin I domain may regulate the function of magnesium chelatase |journal=J. Mol. Biol. |volume=311 |issue=1 |pages=111–122 |year=2001 |pmid=11469861 |doi=10.1006/jmbi.2001.4834}}</ref> 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.<ref name="PUB00011189" /> 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).<ref name="PUB00011189"/>

This enzyme belongs to the family of [[ligase]]s, specifically those forming nitrogen-D-metal bonds in coordination complexes.  The [[List of enzymes|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 B<sub>12</sub>) in [[Aerobic organism|aerobic]] [[bacteria]].

==See also==
* [[Cobalamin biosynthesis]]

== References ==
{{reflist}}

== Further reading ==
{{refbegin}}
* {{cite journal | vauthors = Debussche L, Couder M, Thibaut D, Cameron B, Crouzet J, Blanche F | year = 1992 | title = 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 | journal = J. Bacteriol.  | volume = 174 | pages = 7445&ndash;51  | pmid = 1429466 | issue = 22 | pmc = 207441 | doi = 10.1128/JB.174.22.7445-7451.1992 }}
* {{cite journal | vauthors = Warren MJ, Raux E, Schubert HL, Escalante-Semerena JC | year = 2002 | title = The biosynthesis of adenosylcobalamin (vitamin B12) | journal = Nat. Prod. Rep.  | volume = 19 | pages = 390&ndash;412  | pmid = 12195810 | doi = 10.1039/b108967f | issue = 4 }}
{{refend}}

{{InterPro content|IPR006538}}
{{Phosphoric ester and nitrogen-metal ligases}}
{{Enzymes}}
{{Portal bar|Biology|border=no}}

[[Category:EC 6.6.1]]


{{ligase-stub}}