4f30

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Structure of RPE65: P6522 crystal form grown in ammonium phosphate solutionStructure of RPE65: P6522 crystal form grown in ammonium phosphate solution

Structural highlights

4f30 is a 1 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Ligands:,
Activity:Retinoid isomerohydrolase, with EC number 3.1.1.64
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

[RPE65_BOVIN] Plays important roles in the production of 11-cis retinal and in visual pigment regeneration. The soluble form binds vitamin A (all-trans-retinol), making it available for LRAT processing to all-trans-retinyl ester. The membrane form, palmitoylated by LRAT, binds all-trans-retinyl esters, making them available for IMH (isomerohydrolase) processing to all-cis-retinol. The soluble form is regenerated by transferring its palmitoyl groups onto 11-cis-retinol, a reaction catalyzed by LRAT. The enzymatic activity is linearly dependent of the expression levels and membrane association.[1] [2] [3]

Publication Abstract from PubMed

RPE65 is a key metalloenzyme responsible for maintaining visual function in vertebrates. Despite extensive research on this membrane-bound retinoid isomerase, fundamental questions regarding its enzymology remain unanswered. Here, we report the crystal structure of RPE65 in a membrane-like environment. These crystals, obtained from enzymatically active, nondelipidated protein, displayed an unusual packing arrangement wherein RPE65 is embedded in a lipid-detergent sheet. Structural differences between delipidated and nondelipidated RPE65 uncovered key residues involved in substrate uptake and processing. Complementary iron K-edge X-ray absorption spectroscopy data established that RPE65 as isolated contained a divalent iron center and demonstrated the presence of a tightly bound ligand consistent with a coordinated carboxylate group. These results support the hypothesis that the Lewis acidity of iron could be used to promote ester dissociation and generation of a carbocation intermediate required for retinoid isomerization.

Structure of RPE65 isomerase in a lipidic matrix reveals roles for phospholipids and iron in catalysis.,Kiser PD, Farquhar ER, Shi W, Sui X, Chance MR, Palczewski K Proc Natl Acad Sci U S A. 2012 Oct 9;109(41):E2747-56. doi:, 10.1073/pnas.1212025109. Epub 2012 Sep 24. PMID:23012475[4]

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

See Also

References

  1. ↑ Jin M, Li S, Moghrabi WN, Sun H, Travis GH. Rpe65 is the retinoid isomerase in bovine retinal pigment epithelium. Cell. 2005 Aug 12;122(3):449-59. PMID:16096063 doi:10.1016/j.cell.2005.06.042
  2. ↑ Kiser PD, Golczak M, Lodowski DT, Chance MR, Palczewski K. Crystal structure of native RPE65, the retinoid isomerase of the visual cycle. Proc Natl Acad Sci U S A. 2009 Oct 13;106(41):17325-30. Epub 2009 Oct 5. PMID:19805034
  3. ↑ Golczak M, Kiser PD, Lodowski DT, Maeda A, Palczewski K. Importance of membrane structural integrity for RPE65 retinoid isomerization activity. J Biol Chem. 2010 Mar 26;285(13):9667-82. Epub 2010 Jan 25. PMID:20100834 doi:10.1074/jbc.M109.063941
  4. ↑ Kiser PD, Farquhar ER, Shi W, Sui X, Chance MR, Palczewski K. Structure of RPE65 isomerase in a lipidic matrix reveals roles for phospholipids and iron in catalysis. Proc Natl Acad Sci U S A. 2012 Oct 9;109(41):E2747-56. doi:, 10.1073/pnas.1212025109. Epub 2012 Sep 24. PMID:23012475 doi:http://dx.doi.org/10.1073/pnas.1212025109

4f30, resolution 3.15Å

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