5dqr: Difference between revisions

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== Function ==
== Function ==
[https://www.uniprot.org/uniprot/HCAR_ARATH HCAR_ARATH] Probable iron-sulfur flavoprotein that converts 7-hydroxymethyl chlorophyll a to chlorophyll a using ferredoxin as a reducing equivalent. Catalyzes the reduction of a hydroxymethyl group to a methyl group. Belongs to the chlorophyll catabolic enzymes (CCEs).<ref>PMID:21934147</ref>  
[https://www.uniprot.org/uniprot/HCAR_ARATH HCAR_ARATH] Probable iron-sulfur flavoprotein that converts 7-hydroxymethyl chlorophyll a to chlorophyll a using ferredoxin as a reducing equivalent. Catalyzes the reduction of a hydroxymethyl group to a methyl group. Belongs to the chlorophyll catabolic enzymes (CCEs).<ref>PMID:21934147</ref>  
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== Publication Abstract from PubMed ==
7-Hydroxymethyl chlorophyll a reductase (HCAR) catalyzes the second half-reaction in chlorophyll b to chlorophyll a conversion. HCAR is required for the degradation of light-harvesting complexes and is necessary for efficient photosynthesis by balancing the chlorophyll a/b ratio. Reduction of the hydroxymethyl group uses redox cofactors [4Fe-4S] cluster and FAD to transfer electrons and is difficult because of the strong carbon-oxygen bond. Here, we report the crystal structure of Arabidopsis HCAR at 2.7-A resolution and reveal that two [4Fe-4S]clusters and one FAD within a very short distance form a consecutive electron pathway to the substrate pocket. In vitro kinetic analysis confirms the ferredoxin-dependent electron transport chain, thus supporting a proton-activated electron transfer mechanism. HCAR resembles a partial reconstruction of an archaeal F420-reducing [NiFe] hydrogenase, which suggests a common mode of efficient proton-coupled electron transfer through conserved cofactor arrangements. Furthermore, the trimeric form of HCAR provides a biological clue of its interaction with light-harvesting complex II.
Crystal Structure and Catalytic Mechanism of 7-Hydroxymethyl Chlorophyll a Reductase.,Wang X, Liu L J Biol Chem. 2016 Jun 17;291(25):13349-59. doi: 10.1074/jbc.M116.720342. Epub, 2016 Apr 12. PMID:27072131<ref>PMID:27072131</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
== References ==
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Latest revision as of 12:10, 20 March 2024

The crystal structure of Arabidopsis 7-hydroxymethyl chlorophyll a reductase (HCAR)The crystal structure of Arabidopsis 7-hydroxymethyl chlorophyll a reductase (HCAR)

Structural highlights

5dqr is a 6 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.7Å
Ligands:,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

HCAR_ARATH Probable iron-sulfur flavoprotein that converts 7-hydroxymethyl chlorophyll a to chlorophyll a using ferredoxin as a reducing equivalent. Catalyzes the reduction of a hydroxymethyl group to a methyl group. Belongs to the chlorophyll catabolic enzymes (CCEs).[1]

References

  1. ↑ Meguro M, Ito H, Takabayashi A, Tanaka R, Tanaka A. Identification of the 7-hydroxymethyl chlorophyll a reductase of the chlorophyll cycle in Arabidopsis. Plant Cell. 2011 Sep;23(9):3442-53. doi: 10.1105/tpc.111.089714. Epub 2011 Sep, 20. PMID:21934147 doi:http://dx.doi.org/10.1105/tpc.111.089714

5dqr, resolution 2.70Å

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OCA
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