3KVC

Crystal structure of bovine RPE65 at 1.9 angstrom resolution

PDB DOI: 10.2210/pdb3KVC/pdb

Classification: ISOMERASE
Organism(s): Bos taurus
Mutation(s): Yes

Deposited: 2009-11-29 Released: 2010-02-02
Deposition Author(s): Kiser, P.D., Lodowski, D.T., Golczak, M., Palczewski, K.

Experimental Data Snapshot

Method: X-RAY DIFFRACTION
Resolution: 1.90 Å
R-Value Free: 0.171
R-Value Work: 0.146
R-Value Observed: 0.148

wwPDB Validation 3D Report Full Report

This is version 1.2 of the entry. See complete history.

Literature

Importance of membrane structural integrity for RPE65 retinoid isomerization activity.

Golczak, M., Kiser, P.D., Lodowski, D.T., Maeda, A., Palczewski, K.

(2010) J Biol Chem 285: 9667-9682

PubMed: 20100834 Search on PubMedSearch on PubMed Central
DOI: 10.1074/jbc.M109.063941
Primary Citation of Related Structures:
3KVC

PubMed Abstract:

Regeneration of visual chromophore in the vertebrate visual cycle involves the retinal pigment epithelium-specific protein RPE65, the key enzyme catalyzing the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol. Although RPE65 has no predicted membrane spanning domains, this protein predominantly associates with microsomal fractions isolated from bovine retinal pigment epithelium (RPE). We have re-examined the nature of RPE65 interactions with native microsomal membranes by using extraction and phase separation experiments. We observe that hydrophobic interactions are the dominant forces that promote RPE65 association with these membranes. These results are consistent with the crystallographic model of RPE65, which features a large lipophilic surface that surrounds the entrance to the catalytic site of this enzyme and likely interacts with the hydrophobic core of the endoplasmic reticulum membrane. Moreover, we report a critical role for phospholipid membranes in preserving the retinoid isomerization activity and physical properties of RPE65. Isomerase activity measured in bovine RPE was highly sensitive to phospholipase A(2) treatment, but the observed decline in 11-cis-retinol production did not directly reflect inhibition by products of lipid hydrolysis. Instead, a direct correlation between the kinetics of phospholipid hydrolysis and retinoid isomerization suggests that the lipid membrane structure is critical for RPE65 enzymatic activity. We also provide evidence that RPE65 operates in a multiprotein complex with retinol dehydrogenase 5 and retinal G protein-coupled receptor in RPE microsomes. Modifications in the phospholipid environment affecting interactions with these protein components may be responsible for the alterations in retinoid metabolism observed in phospholipid-depleted RPE microsomes. Thus, our results indicate that the enzymatic activity of native RPE65 strongly depends on its membrane binding and phospholipid environment.

Organizational Affiliation:

Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.

Macromolecules

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(by identity cutoff) | 3D Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Retinoid isomerohydrolase	A, B	533	Bos taurus	Mutation(s): 1 Gene Names: RPE65 EC: 3.1.1.64 (PDB Primary Data), 5.2.1.7 (PDB Primary Data), 5.3.3.22 (UniProt)
UniProt
Find proteins for Q28175 (Bos taurus) Explore Q28175 Go to UniProtKB: Q28175
Entity Groups
Sequence Clusters	30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt Group	Q28175
Protein Feature View Expand
Reference Sequence

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram	3D Interactions
FE2 Query on FE2 Download Ideal Coordinates CCD File SDF format, chain C [auth A] SDF format, chain D [auth B] MOL2 format, chain C [auth A] MOL2 format, chain D [auth B]	C [auth A], D [auth B]	FE (II) ION Fe CWYNVVGOOAEACU-UHFFFAOYSA-N		Ligand Interaction