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Molecular clues to Bothnia-type retinal dystrophy.

Type of publication Peer-reviewed
Publikationsform Contribution to book (peer-reviewed)
Publication date 2012
Author He Xiaoqin, Lobsiger Joel, Stocker Achim,
Project Structural and functional characterization of the retinoid visual cycle in the vertebrate eye
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Contribution to book (peer-reviewed)

Book Retinal Degenerative Diseases
Editor , Anderson R.E.; , Ash J.; , Grimm C.; , LaVail M.M.; , Hollyfield J.G.; , Rickman C.B.
Publisher Springer US, US
Page(s) 589 - 94
ISBN 0065-2598
Title of proceedings Retinal Degenerative Diseases
DOI 10.1007/978-1-4614-0631-0_75

Open Access

URL https://www.boris.unibe.ch/
Type of Open Access Repository (Green Open Access)

Abstract

Cellular retinaldehyde-binding protein (CRALBP) is a 36-kD water soluble protein with an essential chaperone function in mammalian vision (J Biol Chem 252:3267–3271, 1977). CRALBP is only found in retina and pineal gland. It functions in the retinal pigment epithelium (RPE) as a high-affinity receptor of 11-cis-retinol in the isomerization of the rod visual cycle and as a substrate carrier for 11-cis-retinol dehydrogenase. The CRALBP mutant R234W tightens retinoid interactions, which in turn compromise substrate carrier interactions with 11-cis-retinol dehydrogenase and lead to Bothnia-type retinal dystrophy (Invest Ophthalmol Vis Sci 40:995–1000, 1999). Bothnia disease makes patients suffer from night blindness and tunnel vision in earlier age and lose sight in their later life. We crystallized the CRALBP WT-11-cis-retinal complex and the mutant R234W-11-cis-retinal complex, in order to better understand CRALBP visual cycle functions, which require rapid association and dissociation of retinoid. The structures were solved at resolution of 3 and 1.7 Å, respectively (Proc Natl Acad Sci 106:18545–18550, 2009). We compared the R234W structure with wild type, and observed that a one-amino-acid mutation from arginine to tryptophan causes dramatic domino-like arrangements in the retinal-binding pocket of R234W. The volume of the ligand binding cavities was calculated using the VOIDOO program for both, wild type and R234W. We found that the mutant pocket is 7% smaller than wild type with a concomitant increase of packing density. We performed photoisomerization experiment, showing that 11-cis-retinal binds R234W five times tighter than wild type. This is consistent with our crystallographic results. Our findings provide an explanation for the disease mechanism of Bothnia-type retinal dystrophy at the molecular level and give a hint for future drug design.
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