NinaB combines carotenoid oxygenase and retinoid isomerase activity in a single polypeptide

Oberhauser, Vitus; Voolstra, Olaf; Bangert, Annette; Lintig, Johannes von; Vogt, Klaus

doi:10.1073/pnas.0807805105

Cited by 84 publications

(102 citation statements)

References 42 publications

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“…Mechanisms that involve participation of molecular oxygen in the isomerization reaction cannot be definitively ruled out, but would require especially complex chemistry that is not justified by the experimental evidence available to date. Recently, a member of the CCO family, called NinaB, from the Galleria mellonella moth with isomerooxygenase activity was described, indicating that members of this family originally developed isomerase activity while maintaining carotenoid oxygenase activity (35). This finding suggests that the iron cofactor is not directly involved in double bond isomerase activity of NinaB or RPE65.…”

Section: Resultsmentioning

confidence: 65%

Crystal structure of native RPE65, the retinoid isomerase of the visual cycle

Kiser

Golczak²,

Lodowski³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

141

227

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Vertebrate vision is maintained by the retinoid (visual) cycle, a complex enzymatic pathway that operates in the retina to regenerate the visual chromophore, 11-cis-retinal. A key enzyme in this pathway is the microsomal membrane protein RPE65. This enzyme catalyzes the conversion of all-trans-retinyl esters to 11-cis-retinol in the retinal pigment epithelium (RPE). Mutations in RPE65 are known to be responsible for a subset of cases of the most common form of childhood blindness, Leber congenital amaurosis (LCA). Although retinoid isomerase activity has been attributed to RPE65, its catalytic mechanism remains a matter of debate. Also, the manner in which RPE65 binds to membranes and extracts retinoid substrates is unclear. To gain insight into these questions, we determined the crystal structure of native bovine RPE65 at 2.14-Å resolution. The structural, biophysical, and biochemical data presented here provide the framework needed for an in-depth understanding of the mechanism of catalytic isomerization and membrane association, in addition to the role mutations that cause LCA have in disrupting protein function.isomerization ͉ metalloprotein ͉ monotopic membrane protein V ision begins when the 11-cis-retinylidene chromophore of rhodopsin is photoisomerized to all-trans-retinylidene, a process resulting in receptor activation and transduction of the light signal (1). After rhodopsin is photoactivated, it is no longer responsive to light, so for vision to continue, a trans-to-cis isomerization mechanism must be present to regenerate lightsensitive visual pigments. In vertebrates, after photoisomerization, all-trans-retinylidene is hydrolyzed from rhodopsin, reduced to all-trans-retinol, and transported to a tissue adjacent to the photoreceptor layer known as the retinal pigment epithelium (RPE), where enzymatic isomerization occurs (2). An RPEspecific, microsomal membrane protein with an apparent molecular mass of 65 kDa, known as RPE65, was determined to be responsible for trans-to-cis retinoid isomerase activity in the RPE (3-5). The importance of this protein in visual function is also evident from the observation that certain RPE65 mutations cause a form of the hereditary childhood blinding disease known as Leber congenital amaurosis (LCA) or the less severe, lateronset disease, retinitis pigmentosa (RP) (6-8).Based on sequence homology, RPE65 belongs to a family of carotenoid cleavage oxygenase (CCO) enzymes that oxidatively cleave ␤-carotene or apocarotenoids (9-11). However, RPE65 is distinct from all other members of this family in that it simultaneously cleaves and isomerizes all-trans-retinyl esters to 11-cisretinol and a fatty acid rather than oxidatively cleaving carotenoids (3-5, 11, 12). Unlike the reactions catalyzed by other CCO family members, there is no obvious role for molecular oxygen in RPE65 enzymology. The only family member with a known crystal structure is an apocarotenoid oxygenase from Synechocystis that is 25% identical and 42% homologous to human RPE65 (13). All members of this fa...

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Section: Resultsmentioning

confidence: 65%

Crystal structure of native RPE65, the retinoid isomerase of the visual cycle

Kiser

Golczak²,

Lodowski³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

141

227

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“…Extraction of Carotenoids and Retinoids and HPLC Analyses-Lipid compounds from flies were extracted and HPLC procedures were carried out as described previously (17,25,29). All extractions were carried out under a red safety light.…”

Section: Whole Mount In Situ Hybridization Of Drosophila Embryos-mentioning

confidence: 99%

“…Test for Enzymatic Activity-For heterologous expression, expression vectors for Drosophila and Galleria NinaB (25), were transformed in the Escherichia coli strain XL1-blue (Stratagene, La Jolla, CA). Bacteria were grown at 28°C to an A 600 of 0.5.…”

Section: Whole Mount In Situ Hybridization Of Drosophila Embryos-mentioning

confidence: 99%

“…In flies, an 11-cis configuration of retinoids is also essential for visual pigment biogenesis (12,25,26). Although preformed retinoids such as all-trans-retinal support visual pigment production only in the presence of light, carotenoids can promote visual pigment production light independently (25).…”

mentioning

confidence: 99%

“…Although preformed retinoids such as all-trans-retinal support visual pigment production only in the presence of light, carotenoids can promote visual pigment production light independently (25). Biochemical analysis shows that NinaB from the moth Galleria mellonella combines the activities of a carotenoid oxygenase and a retinoid isomerase in a single polypeptide (25). In this isomerooxygenase reaction, carotenoids such as zeaxanthin are lightindependently converted to one molecule of 11-cis-and one molecule of all-trans-3-hydroxy-retinal.…”

mentioning

confidence: 99%

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NinaB Is Essential for Drosophila Vision but Induces Retinal Degeneration in Opsin-deficient Photoreceptors

Voolstra

Oberhauser

Sumser

et al. 2010

Journal of Biological Chemistry

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In animals, visual pigments are essential for photoreceptor function and survival. These G-protein-coupled receptors consist of a protein moiety (opsin) and a covalently bound 11-cis-retinylidene chromophore. The chromophore is derived from dietary carotenoids by oxidative cleavage and trans-to-cis isomerization of double bonds. In vertebrates, the necessary chemical transformations are catalyzed by two distinct but structurally related enzymes, the carotenoid oxygenase ␤-carotenoid-15,15-monooxygenase and the retinoid isomerase RPE65 (retinal pigment epithelium protein of 65 kDa). Recently, we provided biochemical evidence that these reactions in insects are catalyzed by a single enzyme family member named NinaB. Here we show that in the fly pathway, carotenoids are mandatory precursors of the chromophore. After chromophore formation, the retinoid-binding protein Pinta acts downstream of NinaB and is required to supply photoreceptors with chromophore. Like ninaE encoding the opsin, ninaB expression is eye-dependent and is activated as a downstream target of the eyeless/pax6 and sine oculis master control genes for eye development. The requirement for coordinated synthesis of chromophore and opsin is evidenced by analysis of ninaE mutants. Retinal degeneration in opsin-deficient photoreceptors is caused by the chromophore and can be prevented by restricting its supply as seen in an opsin and chromophore-deficient double mutant. Thus, our study identifies NinaB as a key component for visual pigment production and provides evidence that chromophore in opsin-deficient photoreceptors can elicit retinal degeneration.Photoreceptors are sensory neurons with specialized lightsensitive compartments, the outer segments of vertebrate cones and rods and the rhabdomeres of insects. These structures are orderly stacks of photosensitive plasma membrane that house the phototransduction machinery. Light sensitivity is mediated by visual pigments, the major protein constituent of these membranes. Visual pigments are G-protein-coupled receptors that consist of an integral membrane protein, referred as the opsin, and an 11-cis-retinylidene chromophore covalently linked to a lysine residue through a Schiff base linkage (reviewed in Ref. 1). Visual pigment biogenesis is a complex process that involves the transport of the opsin through the secretory pathway to photosensitive membranes and the metabolic supply of the chromophore. It is now clear that mutations resulting in ineffective visual pigment biogenesis and pigment regeneration after a bleach are an important cause of retinal degeneration and blindness in humans (for recent reviews see Refs. 2, 3).Drosophila have long served as an animal model to analyze visual pigment biogenesis and study the pathology of associated blinding diseases (for recent review see Ref. 4). The first mutations linked to retinal degeneration were noted in the ninaE gene (neither inactivation nor afterpotential mutant E) (5, 6). ninaE encodes the opsin moiety of the flies' major visual pigment (Rh1) 2 an...

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Retinoids and the Visual Cycle

Babino

Lintig

2015

The Retinoids

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NinaB combines carotenoid oxygenase and retinoid isomerase activity in a single polypeptide

Cited by 84 publications

References 42 publications

Crystal structure of native RPE65, the retinoid isomerase of the visual cycle

Crystal structure of native RPE65, the retinoid isomerase of the visual cycle

NinaB Is Essential for Drosophila Vision but Induces Retinal Degeneration in Opsin-deficient Photoreceptors

Retinoids and the Visual Cycle

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