Magnesium chelatase

magnesium chelatase
Identifiers
EC number	6.6.1.1
CAS number	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 / EGO
Search PMC articles PubMed articles NCBI proteins

Magnesium chelatase, ChlI subunit
Identifiers
Symbol	Mg_chelatse_chII
Pfam	PF01078
InterPro	IPR000523
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

CobN/magnesium chelatase
Identifiers
Symbol	CobN/Mg_chltase
Pfam	PF02514
InterPro	IPR003672
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Magnesium-chelatase is a three-component enzyme that catalyses the insertion of Mg²⁺ into protoporphyrin IX. This is the first unique step in the synthesis of bacteriochlorophyll. 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:

protoporphyrin IX + Mg2+
+ ATP + H
2O $\rightleftharpoons$ ADP + phosphate + Mg-protoporphyrin IX + 2 H+

The 4 substrates of this enzyme are ATP, protoporphyrin IX, Mg²⁺, and H₂O, whereas its 4 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 participates in porphyrin and chlorophyll metabolism.

References

• 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. 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.