1
|
Hong JD, Salom D, Choi EH, Du SW, Tworak A, Smidak R, Gao F, Solano YJ, Zhang J, Kiser PD, Palczewski K. Retinylidene chromophore hydrolysis from mammalian visual and non-visual opsins. J Biol Chem 2024; 300:105678. [PMID: 38272218 PMCID: PMC10877631 DOI: 10.1016/j.jbc.2024.105678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/06/2024] [Accepted: 01/13/2024] [Indexed: 01/27/2024] Open
Abstract
Rhodopsin (Rho) and cone opsins are essential for detection of light. They respond via photoisomerization, converting their Schiff-base-adducted 11-cis-retinylidene chromophores to the all-trans configuration, eliciting conformational changes to activate opsin signaling. Subsequent Schiff-base hydrolysis releases all-trans-retinal, initiating two important cycles that maintain continuous vision-the Rho photocycle and visual cycle pathway. Schiff-base hydrolysis has been thoroughly studied with photoactivated Rho but not with cone opsins. Using established methodology, we directly measured the formation of Schiff-base between retinal chromophores with mammalian visual and nonvisual opsins of the eye. Next, we determined the rate of light-induced chromophore hydrolysis. We found that retinal hydrolysis from photoactivated cone opsins was markedly faster than from photoactivated Rho. Bovine retinal G protein-coupled receptor (bRGR) displayed rapid hydrolysis of its 11-cis-retinylidene photoproduct to quickly supply 11-cis-retinal and re-bind all-trans-retinal. Hydrolysis within bRGR in native retinal pigment epithelium microsomal membranes was >6-times faster than that of bRGR purified in detergent micelles. N-terminal-targeted antibodies significantly slowed bRGR hydrolysis, while C-terminal antibodies had no effect. Our study highlights the much faster photocycle of cone opsins relative to Rho and the crucial role of RGR in chromophore recycling in daylight. By contrast, in our experimental conditions, bovine peropsin did not form pigment in the presence of all-trans-retinal nor with any mono-cis retinal isomers, leaving uncertain the role of this opsin as a light sensor.
Collapse
Affiliation(s)
- John D Hong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Chemistry, University of California Irvine, Irvine, California, USA
| | - David Salom
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA.
| | - Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Samuel W Du
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA
| | - Aleksander Tworak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Roman Smidak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Fangyuan Gao
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Yasmeen J Solano
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA
| | - Jianye Zhang
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA; Department of Clinical Pharmacy Practice, University of California Irvine, Irvine, California, USA; Research Service, VA Long Beach Healthcare System, Long Beach, California, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA; Department of Chemistry, University of California Irvine, Irvine, California, USA; Department of Physiology and Biophysics, University of California Irvine, Irvine, California, USA; Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California, USA.
| |
Collapse
|
2
|
Zhu P, Dyka F, Ma X, Yin L, Yu H, Baehr W, Hauswirth WW, Deng WT. Disease mechanisms of X-linked cone dystrophy caused by missense mutations in the red and green cone opsins. FASEB J 2021; 35:e21927. [PMID: 34547123 PMCID: PMC8462070 DOI: 10.1096/fj.202101066r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/12/2021] [Accepted: 08/31/2021] [Indexed: 11/11/2022]
Abstract
Cone photoreceptors are responsible for the visual acuity and color vision of the human eye. Red/green cone opsin missense mutations N94K, W177R, P307L, R330Q, and G338E have been identified in subjects with congenital blue cone monochromacy or color‐vision deficiency. Studies on disease mechanisms due to these cone opsin mutations have been previously carried out exclusively in vitro, and the reported impairments were not always consistent. Here we expressed these mutants via AAV specifically in vivo in M‐opsin knockout mouse cones to investigate their subcellular localization, the pathogenic effects on cone structure, function, and cone viability. We show that these mutations alter the M‐opsin structure, function, and localization. N94K and W177R mutants appeared to be misfolded since they localized exclusively in cone inner segments and endoplasmic reticulum. In contrast, P307L, R330Q, and G338E mutants were detected predominately in cone outer segments. Expression of R330Q and G338E, but not P307L opsins, also partially restored expression and correct localization of cone PDE6α’ and cone transducin γ and resulted in partial rescue of M‐cone‐mediated light responses. Expression of W177R and P307L mutants significantly reduced cone viability, whereas N94K, R330Q, and G338E were only modestly toxic. We propose that although the underlying biochemical and cellular defects caused by these mutants are distinct, they all seem to exhibit a dominant phenotype, resembling autosomal dominant retinitis pigmentosa associated with the majority of rhodopsin missense mutations. The understanding of the molecular mechanisms associated with these cone opsin mutants is fundamental to developing targeted therapies for cone dystrophy/dysfunction.
Collapse
Affiliation(s)
- Ping Zhu
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Frank Dyka
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Xiaojie Ma
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Ling Yin
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Heather Yu
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Wolfgang Baehr
- Department of Ophthalmology, John A. Moran Eye Center, University of Utah Health Science Center, Salt Lake City, Utah, USA.,Department of Neurobiology and Anatomy, University of Utah Health Science Center, Salt Lake City, Utah, USA.,Department of Biology, University of Utah, Salt Lake City, Utah, USA
| | - William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Wen-Tao Deng
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| |
Collapse
|
3
|
James EI, Murphree TA, Vorauer C, Engen JR, Guttman M. Advances in Hydrogen/Deuterium Exchange Mass Spectrometry and the Pursuit of Challenging Biological Systems. Chem Rev 2021; 122:7562-7623. [PMID: 34493042 PMCID: PMC9053315 DOI: 10.1021/acs.chemrev.1c00279] [Citation(s) in RCA: 102] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Solution-phase hydrogen/deuterium
exchange (HDX) coupled to mass
spectrometry (MS) is a widespread tool for structural analysis across
academia and the biopharmaceutical industry. By monitoring the exchangeability
of backbone amide protons, HDX-MS can reveal information about higher-order
structure and dynamics throughout a protein, can track protein folding
pathways, map interaction sites, and assess conformational states
of protein samples. The combination of the versatility of the hydrogen/deuterium
exchange reaction with the sensitivity of mass spectrometry has enabled
the study of extremely challenging protein systems, some of which
cannot be suitably studied using other techniques. Improvements over
the past three decades have continually increased throughput, robustness,
and expanded the limits of what is feasible for HDX-MS investigations.
To provide an overview for researchers seeking to utilize and derive
the most from HDX-MS for protein structural analysis, we summarize
the fundamental principles, basic methodology, strengths and weaknesses,
and the established applications of HDX-MS while highlighting new
developments and applications.
Collapse
Affiliation(s)
- Ellie I James
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Taylor A Murphree
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Clint Vorauer
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - John R Engen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Miklos Guttman
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| |
Collapse
|
4
|
Han X, Hofmann L, de la Fuente M, Alexander N, Palczewski K, Nieman MT. PAR4 activation involves extracellular loop 3 and transmembrane residue Thr153. Blood 2020; 136:2217-2228. [PMID: 32575122 PMCID: PMC7645988 DOI: 10.1182/blood.2019004634] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 05/24/2020] [Indexed: 12/17/2022] Open
Abstract
Protease-activated receptor 4 (PAR4) mediates sustained thrombin signaling in platelets and is required for a stable thrombus. PAR4 is activated by proteolysis of the N terminus to expose a tethered ligand. The structural basis for PAR4 activation and the location of its ligand binding site (LBS) are unknown. Using hydrogen/deuterium exchange (H/D exchange), computational modeling, and signaling studies, we determined the molecular mechanism for tethered ligand-mediated PAR4 activation. H/D exchange identified that the LBS is composed of transmembrane 3 (TM3) domain and TM7. Unbiased computational modeling further predicted an interaction between Gly48 from the tethered ligand and Thr153 from the LBS. Mutating Thr153 significantly decreased PAR4 signaling. H/D exchange and modeling also showed that extracellular loop 3 (ECL3) serves as a gatekeeper for the interaction between the tethered ligand and LBS. A naturally occurring sequence variant (P310L, rs2227376) and 2 experimental mutations (S311A and P312L) determined that the rigidity conferred by prolines in ECL3 are essential for PAR4 activation. Finally, we examined the role of the polymorphism at position 310 in venous thromboembolism (VTE) using the International Network Against Venous Thrombosis (INVENT) consortium multi-ancestry genome-wide association study (GWAS) meta-analysis. Individuals with the PAR4 Leu310 allele had a 15% reduction in relative risk for VTE (odds ratio, 0.85; 95% confidence interval, 0.77-0.94) compared with the Pro310 allele. These data are consistent with our H/D exchange, molecular modeling, and signaling studies. In conclusion, we have uncovered the structural basis for PAR4 activation and identified a previously unrecognized role for PAR4 in VTE.
Collapse
Affiliation(s)
- Xu Han
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| | - Lukas Hofmann
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| | | | - Nathan Alexander
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| | | | - Marvin T Nieman
- Case Western Reserve University, School of Medicine, Cleveland, OH; and
| |
Collapse
|
5
|
Salom D, Jin H, Gerken TA, Yu C, Huang L, Palczewski K. Human red and green cone opsins are O-glycosylated at an N-terminal Ser/Thr-rich domain conserved in vertebrates. J Biol Chem 2019; 294:8123-8133. [PMID: 30948514 DOI: 10.1074/jbc.ra118.006835] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/15/2019] [Indexed: 12/28/2022] Open
Abstract
There are fundamental differences in the structures of outer segments between rod and cone photoreceptor cells in the vertebrate retina. Visual pigments are the only essential membrane proteins that differ between rod and cone outer segments, making it likely that they contribute to these structural differences. Human rhodopsin is N-glycosylated on Asn2 and Asn15, whereas human (h) red and green cone opsins (hOPSR and hOPSG, respectively) are N-glycosylated at Asn34 Here, utilizing a monoclonal antibody (7G8 mAB), we demonstrate that hOPSR and hOPSG from human retina also are O-glycosylated with full occupancy. We determined that 7G8 mAB recognizes the N-terminal sequence 21DSTQSSIF28 of hOPSR and hOPSG from extracts of human retina, but only after their O-glycans have been removed with O-glycosidase treatment, thus revealing this post-translational modification of red and green cone opsins. In addition, we show that hOPSR and hOPSG from human retina are recognized by jacalin, a lectin that binds to O-glycans, preferentially to Gal-GalNAc. Next, we confirmed the presence of O-glycans on OPSR and OPSG from several vertebrate species, including mammals, birds, and amphibians. Finally, the analysis of bovine OPSR by MS identified an O-glycan on Ser22, a residue that is semi-conserved (Ser or Thr) among vertebrate OPSR and OPSG. These results suggest that O-glycosylation is a fundamental feature of red and green cone opsins, which may be relevant to their function or to cone cell development, and that differences in this post-translational modification also could contribute to the different morphologies of rod and cone photoreceptors.
Collapse
Affiliation(s)
- David Salom
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, Irvine, California 92697; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106.
| | - Hui Jin
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Thomas A Gerken
- Department of Biochemistry and Chemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute and the Department of Ophthalmology, University of California, Irvine, Irvine, California 92697; Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106.
| |
Collapse
|
6
|
Calabrese AN, Radford SE. Mass spectrometry-enabled structural biology of membrane proteins. Methods 2018; 147:187-205. [DOI: 10.1016/j.ymeth.2018.02.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/30/2018] [Accepted: 02/21/2018] [Indexed: 01/01/2023] Open
|