Magnesium-chelatase is a three-component enzyme (EC 6.6.1.1) that catalyses the insertion of Mg2+ into protoporphyrin IX. This is the first unique step in the synthesis of chlorophyll and bacteriochlorophyll.[1][2] As a result, it is thought that Mg-chelatase has an important role in channeling intermediates into the (bacterio)chlorophyll branch in response to conditions suitable for photosynthetic growth:
| Magnesium chelatase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 Magnesium chelatase hetero12mer, Rhodobacter capsulatus | |||||||||
| Identifiers | |||||||||
| EC no. | 6.6.1.1 | ||||||||
| CAS no. | 9074-88-8 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
| Magnesium chelatase, ChlI subunit | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||||
| Symbol | Mg_chelatse_chII | ||||||||||
| Pfam | PF01078 | ||||||||||
| InterPro | IPR000523 | ||||||||||
| |||||||||||
| CobN/magnesium chelatase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | CobN/Mg_chltase | ||||||||
| Pfam | PF02514 | ||||||||
| InterPro | IPR003672 | ||||||||
| |||||||||
+ ATP + H
2O ADP + phosphate + Mg-protoporphyrin IX + 2 H+
The four substrates of this enzyme are ATP, protoporphyrin IX, Mg2+, and H2O; its four products are ADP, phosphate, Mg-protoporphyrin IX, and H+.
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 Mg-protoporphyrin IX magnesium-lyase. Other names in common use include protoporphyrin IX magnesium-chelatase, protoporphyrin IX Mg-chelatase, magnesium-protoporphyrin IX chelatase, magnesium-protoporphyrin chelatase, magnesium-chelatase, Mg-chelatase, and Mg-protoporphyrin IX magnesio-lyase. This enzyme is part of the biosynthetic pathway to chlorophylls.
See also
editReferences
edit- ^ Willows, Robert D. (2003). "Biosynthesis of chlorophylls from protoporphyrin IX". Natural Product Reports. 20 (6): 327–341. doi:10.1039/B110549N. PMID 12828371.
- ^ Bollivar, David W. (2007). "Recent advances in chlorophyll biosynthesis". Photosynthesis Research. 90 (2): 173–194. doi:10.1007/s11120-006-9076-6. PMID 17370354. S2CID 23808539.
- Walker CJ, Weinstein JD (1991). "In vitro assay of the chlorophyll biosynthetic enzyme Mg-chelatase: resolution of the activity into soluble and membrane-bound fractions". Proc. Natl. Acad. Sci. U.S.A. 88 (13): 5789–93. Bibcode:1991PNAS...88.5789W. doi:10.1073/pnas.88.13.5789. PMC 51963. PMID 11607197.
- Walker CJ, Willows RD (Oct 15, 1997). "Mechanism and regulation of Mg-chelatase". Biochem. J. 327 (2): 321–33. doi:10.1042/bj3270321. PMC 1218797. PMID 9359397.
- Al-Karadaghi S; Hansson, A; Hansson, M; Olsen, JG; Gough, S; Willows, RD; Al-Karadaghi, S (2001). "Interplay between an AAA module and an integrin I domain may regulate the function of magnesium chelatase". J. Mol. Biol. 311 (1): 111–22. doi:10.1006/jmbi.2001.4834. PMID 11469861.
