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6ytn

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Magnesium chelatase H subunit (ChlH) E660W variant from Synechocystis sp.PCC6803

Structural highlights

6ytn is a 2 chain structure with sequence from Synechocystis sp. PCC 6803. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.7Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

P73020_SYNY3

Publication Abstract from PubMed

The insertion of magnesium into protoporphyrin initiates the biosynthesis of chlorophyll, the pigment that underpins photosynthesis. This reaction, catalysed by the magnesium chelatase complex, couples ATP hydrolysis by a ChlID motor complex to chelation within the ChlH subunit. We probed the structure and catalytic function of ChlH using a combination of X-ray crystallography, computational modelling, mutagenesis and enzymology. Two linked domains of ChlH in an initially open conformation of ChlH bind protoporphyrin IX, and the rearrangement of several loops envelops this substrate, forming an active site cavity. This induced fit brings an essential glutamate (E660), proposed to be the key catalytic residue for magnesium insertion, into proximity with the porphyrin. A buried solvent channel adjacent to E660 connects the exterior bulk solvent to the active site, forming a possible conduit for the delivery of magnesium or abstraction of protons.

The active site of magnesium chelatase.,Adams NBP, Bisson C, Brindley AA, Farmer DA, Davison PA, Reid JD, Hunter CN Nat Plants. 2020 Nov 30. pii: 10.1038/s41477-020-00806-9. doi:, 10.1038/s41477-020-00806-9. PMID:33257858^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Adams NBP, Bisson C, Brindley AA, Farmer DA, Davison PA, Reid JD, Hunter CN. The active site of magnesium chelatase. Nat Plants. 2020 Nov 30. pii: 10.1038/s41477-020-00806-9. doi:, 10.1038/s41477-020-00806-9. PMID:33257858 doi:http://dx.doi.org/10.1038/s41477-020-00806-9