title: Inherent instability of the retinitis pigmentosa P23H mutant opsin.
abstract: The P23H opsin mutation is the most common cause of autosomal dominant retinitis pigmentosa. Even though the pathobiology of the resulting retinal degeneration has been characterized in several animal models, its complex molecular mechanism is not well understood. Here, we expressed P23H bovine rod opsin in the nervous system of Caenorhabditis elegans. Expression was low due to enhanced protein degradation. The mutant opsin was glycosylated, but the polysaccharide size differed from that of the normal protein. Although P23H opsin aggregated in the nervous system of C. elegans, the pharmacological chaperone 9-cis-retinal stabilized it during biogenesis, producing a variant of rhodopsin called P23H isorhodopsin. In vitro, P23H isorhodopsin folded correctly, formed the appropriate disulfide bond, could be photoactivated but with reduced sensitivity, and underwent Meta II decay at a rate similar to wild type isorhodopsin. In worm neurons, P23H isorhodopsin initiated phototransduction by coupling with the endogenous Gi/o signaling cascade that induced loss of locomotion. Using pharmacological interventions affecting protein synthesis and degradation, we showed that the chromophore could be incorporated either during or after mutant protein translation. However, regeneration of P23H isorhodopsin with chromophore was significantly slower than that of wild type isorhodopsin. This effect, combined with the inherent instability of P23H rhodopsin, could lead to the structural cellular changes and photoreceptor death found in autosomal dominant retinitis pigmentosa. These results also suggest that slow regeneration of P23H rhodopsin could prevent endogenous chromophore-mediated stabilization of rhodopsin in the retina.
authors: From the Department of Pharmacology.
authors: Yuanyuan
authors: Y
authors: Chen
authors: Beata
authors: B
authors: Jastrzebska
authors: Pengxiu
authors: P
authors: Cao
authors: Jianye
authors: J
authors: Zhang
authors: Benlian
authors: B
authors: Wang
authors: Wenyu
authors: W
authors: Sun
authors: Yiyuan
authors: Y
authors: Yuan
authors: Zhaoyang
authors: Z
authors: Feng
authors: Krzysztof
authors: K
authors: Palczewski
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics; D002417:Cattle; D016923:Cell Death; D004220:Disulfides / Q000737:chemistry; D008027:Light; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010786:Photoreceptor Cells / Q000473:pathology; D055550:Protein Stability; D012174:Retinitis Pigmentosa / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017299:Rod Opsins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D004220:Disulfides; D050505:Mutant Proteins; D017299:Rod Opsins
keywords: G Protein-coupled Receptors; Retina; Retinal Degeneration; Vision; Vitamin A