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https://www.readbyqxmd.com/read/28533401/evolutionary-steps-involving-counterion-displacement-in-a-tunicate-opsin
#1
Keiichi Kojima, Takahiro Yamashita, Yasushi Imamoto, Takehiro G Kusakabe, Motoyuki Tsuda, Yoshinori Shichida
Ci-opsin1 is a visible light-sensitive opsin present in the larval ocellus of an ascidian, Ciona intestinalis This invertebrate opsin belongs to the vertebrate visual and nonvisual opsin groups in the opsin phylogenetic tree. Ci-opsin1 contains candidate counterions (glutamic acid residues) at positions 113 and 181; the former is a newly acquired position in the vertebrate visual opsin lineage, whereas the latter is an ancestral position widely conserved among invertebrate opsins. Here, we show that Glu113 and Glu181 in Ci-opsin1 act synergistically as counterions, which imparts molecular properties to Ci-opsin1 intermediate between those of vertebrate- and invertebrate-type opsins...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28527429/coexistence-of-light-driven-na-and-h-transport-in-a-microbial-rhodopsin-from-nonlabens-dokdonensis
#2
Hongshen Zhao, Baofu Ma, Liangliang Ji, Longjie Li, Huanhuan Wang, Deliang Chen
Ion pumping microbial rhodopsins are photochemically active membrane proteins, converting light energy into ion-motive-force for ATP synthesis. Nonlabens dokdonensis rhodopsin 2 (NdR2), was recently identified as a light-driven Na(+) pump. However, few functional studies on NdR2 have been conducted to elucidate its mechanism of ion transport. By reconstituting NdR2 into liposomes, we proved that NdR2 functions as a light-driven Na(+)/H(+) pump. As Na(+) concentration increased, the dominant H(+) pump activity switched to the Na(+) pump activity at neutral pH...
May 10, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28524165/molecular-assembly-of-rhodopsin-with-g-protein-coupled-receptor-kinases
#3
Yuanzheng He, Xiang Gao, Devrishi Goswami, Li Hou, Kuntal Pal, Yanting Yin, Gongpu Zhao, Oliver P Ernst, Patrick Griffin, Karsten Melcher, H Eric Xu
G protein-coupled receptor kinases (GRKs) play pivotal roles in desensitizing GPCR signaling but little is known about how GRKs recognize and phosphorylate GPCRs due to the technical difficulties in detecting the highly dynamic GPCR/GRK interaction. By combining a genetic approach with multiple biochemical assays, we identified the key determinants for the assembly of the prototypical GPCR rhodopsin with its kinase GRK1. Our work reveals that the regulatory G-protein signaling homology (RH) domain of GRKs is the primary binding site to GPCRs and an active conformation of the GRK1 kinase domain is required for efficient interaction with rhodopsin...
May 19, 2017: Cell Research
https://www.readbyqxmd.com/read/28518188/ph-dependent-absorption-spectrum-of-a-protein-a-minimal-electrostatic-model-of-anabaena-sensory-rhodopsin
#4
Michael Stenrup, Elisa Pieri, Vincent Ledentu, Nicolas Ferré
A minimal electrostatic model is introduced which aims at reproducing and analyzing the visible-light absorption energy shift of a protein with pH. It relies on the existence of a protein structure, the prediction of titratable amino-acid pKa values and a very limited set of parameters. Applied to the case of the photochromic Anabaena sensory rhodopsin protein, the model succeeds in reproducing qualitatively the reported experimental data, confirming the importance of aspartic acid 217 in the observed blue shift in the λmax of ASR at neutral pH...
May 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28515229/unique-cell-biological-profiles-of-retinal-disease-causing-missense-mutations-in-the-polarity-protein-crumbs
#5
Milena Pellikka, Ulrich Tepass
Mutations in human CRB1 are a major cause of retinal disease that lead to blindness. CRB1 is a transmembrane protein found in the inner segment of photoreceptor cells (PRCs) and the apical membrane of Müller glia. The function of the extracellular region of CRB1 is poorly understood although more than 80 disease-causing missense mutations have been mapped to it. We have recreated four mutations in Drosophila Crumbs (Crb) that affect different extracellular domains. Crb regulates epithelial polarity and growth, and contributes to PRC differentiation and survival...
May 17, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28507272/phosphatidylinositol-5-phosphate-4-kinase-regulates-early-endosomal-dynamics-during-clathrin-mediated-endocytosis
#6
Kumari Kamalesh, Deepti Trivedi, Sarah Toscano, Sanjeev Sharma, Sourav Kolay, Padinjat Raghu
Endocytic turnover is essential to regulate the protein composition and function of the plasma membrane thus regulating the plasma membrane levels of many receptors. In Drosophila photoreceptors, photon absorption by the GPCR rhodopsin 1 (Rh1) triggers its endocytosis by clathrin-mediated endocytosis (CME). We find that CME of Rh1 is regulated by phosphatidylinositol 5 phosphate 4-kinase (PIP4K). Flies lacking PIP4K show mislocalization of Rh1 on expanded endomembranes within the cell body. This mislocalization of Rh1 was dependent on the formation of an expanded Rab5 compartment...
May 15, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28501588/oligomeric-structure-of-anabaena-sensory-rhodopsin-in-a-lipid-bilayer-environment-by-combining-solid-state-nmr-and-long-range-deer-constraints
#7
Sergey Milikisiyants, Shenlin Wang, Rachel A Munro, Matthew Donohue, Meaghan E Ward, David Bolton, Leonid S Brown, Tatyana I Smirnova, Vladimir Ladizhansky, Alex I Smirnov
Oligomerization of membrane proteins is common in nature. Here, we combine spin-labeling Double Electron-Electron Resonance (DEER) and solid-state NMR (ssNMR) spectroscopy to refine the structure of an oligomeric integral membrane protein, Anabaena Sensory Rhodopsin (ASR), reconstituted in a lipid environment. An essential feature of such a combined approach is that it provides structural distance restraints spanning a range of ca. 3-60Å, while using the same sample preparation (i.e., mutations, paramagnetic labeling, and reconstitution in lipid bilayers) for both ssNMR and DEER...
May 10, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28500716/functional-expression-of-gloeobacter-rhodopsin-in-synechocystis-sp-pcc6803
#8
Que Chen, Jos Arents, Srividya Ganapathy, Willem J de Grip, Klaas J Hellingwerf
Proteorhodopsins are light-driven proton pumps that occur widespread in Nature, where they function predominantly in environments with high incident irradiance. Their maximal absorbance is usually in the blue range, but can be extended into the (far)red range of the electromagnetic spectrum. Because they can be expressed heterologously, they may be exploited in studies aimed at increasing the efficiency of photosynthesis. Here we report further studies toward this goal, by comparing the expression of two different bacterial rhodopsins (Proteorhodopsin and Gloeobacter rhodopsin) in the model cyanobacterium Synechocystis sp...
May 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28500714/sensory-rhodopsin-i-and-sensory-rhodopsin-ii-form-trimers-of-dimers-in-complex-with-their-cognate-transducers
#9
Philipp Orekhov, Arne Bothe, Heinz-Jürgen Steinhoff, Konstantin V Shaitan, Stefan Raunser, Dimitrios Fotiadis, Ramona Schlesinger, Johann P Klare, Martin Engelhard
Archaeal photoreceptors consist of sensory rhodopsins in complex with their cognate transducers. After light excitation, a two-component signaling chain is activated, which is homologous to the chemotactic signaling cascades in enterobacteria. The latter system has been studied in detail. From structural and functional studies, a picture emerges which includes stable signaling complexes, which assemble to receptor arrays displaying hexagonal structural elements. At this higher order structural level, signal amplification and sensory adaptation occur...
May 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28500713/photochemical-properties-of-the-red-shifted-channelrhodopsin-chrimson
#10
David Urmann, Charlotte Lorenz, Stephanie M Linker, Markus Braun, Josef Wachtveitl, Christian Bamann
Color-tuned variants of channelrhodopsins allow for selective optogenetic manipulation of different host cell populations. Chrimson is the channelrhodopsin with the longest wavelength absorbance maximum. We characterize its photochemical properties at different pH values corresponding to two protonation states of the counterion for the protonated Schiff base. Both states will lead to a functional channel opening, but the route is different as reflected in the photochemical states observed spectroscopically...
May 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28500442/drosophila-rhodopsin-7-can-partially-replace-the-structural-role-of-rhodopsin-1-but-not-its-physiological-function
#11
Rudi Grebler, Christa Kistenpfennig, Dirk Rieger, Joachim Bentrop, Stephan Schneuwly, Pingkalai R Senthilan, Charlotte Helfrich-Förster
Rhodopsin 7 (Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000 and thought to encode for a functional Rhodopsin protein. Indeed, Rh7 exhibits most hallmarks of the known Rhodopsins, except for the G-protein-activating QAKK motif in the third cytoplasmic loop that is absent in Rh7. Here, we show that Rh7 can partially substitute Rh1 in the outer receptor cells (R1-6) for rhabdomere maintenance, but that it cannot activate the phototransduction cascade in these cells...
May 12, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/28493967/water-permeation-through-the-internal-water-pathway-in-activated-gpcr-rhodopsin
#12
Katsufumi Tomobe, Eiji Yamamoto, Kholmirzo Kholmurodov, Kenji Yasuoka
Rhodopsin is a light-driven G-protein-coupled receptor that mediates signal transduction in eyes. Internal water molecules mediate activation of the receptor in a rhodopsin cascade reaction and contribute to conformational stability of the receptor. However, it remains unclear how internal water molecules exchange between the bulk and protein inside, in particular through a putative solvent pore on the cytoplasmic. Using all-atom molecular dynamics simulations, we identified the solvent pore on cytoplasmic side in both the Meta II state and the Opsin...
2017: PloS One
https://www.readbyqxmd.com/read/28490005/opposing-effects-of-valproic-acid-treatment-mediated-by-histone-deacetylase-inhibitor-activity-in-four-transgenic-x-laevis-models-of-retinitis-pigmentosa
#13
Ruanne Y J Vent-Schmidt, Runxia H Wen, Zusheng Zong, Colette N Chiu, Beatrice M Tam, Christopher G May, Orson L Moritz
Retinitis pigmentosa (RP) is an inherited retinal degeneration (RD) that leads to blindness for which no treatment is available. RP is frequently caused by mutations in Rhodopsin; in some animal models, RD is exacerbated by light. Valproic acid (VPA) is a proposed treatment for RP and other neurodegenerative disorders, with a phase II trial for RP under way. However, the therapeutic mechanism is unclear, with minimal research supporting its use in RP. We investigated the effects of VPA on Xenopus laevis models of RP expressing human P23H, T17M, T4K, and Q344ter rhodopsins, which are associated with RP in humans...
January 25, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28489826/a-rhodopsin-in-the-brain-functions-in-circadian-photoentrainment-in-drosophila
#14
Jinfei D Ni, Lisa S Baik, Todd C Holmes, Craig Montell
Animals partition their daily activity rhythms through their internal circadian clocks, which are synchronized by oscillating day-night cycles of light. The fruitfly Drosophila melanogaster senses day-night cycles in part through rhodopsin-dependent light reception in the compound eye and photoreceptor cells in the Hofbauer-Buchner eyelet. A more noteworthy light entrainment pathway is mediated by central pacemaker neurons in the brain. The Drosophila circadian clock is extremely sensitive to light. However, the only known light sensor in pacemaker neurons, the flavoprotein cryptochrome (Cry), responds only to high levels of light in vitro...
May 10, 2017: Nature
https://www.readbyqxmd.com/read/28487362/complex-binding-pathways-determine-the-regeneration-of-mammalian-green-cone-opsin-with-a-locked-retinal-analogue
#15
Nathan S Alexander, Kota Katayama, Wenyu Sun, David Salom, Sahil Gulati, Jianye Zhang, Muneto Mogi, Krzysztof Palczewski, Beata Jastrzebska
Phototransduction is initiated when the absorption of light converts the 11-cis-retinal chromophore to its all-trans configuration in both rod and cone vertebrate photoreceptors. To sustain vision, 11-cis-retinal is continuously regenerated from its all-trans conformation through a series of enzymatic steps comprising the visual or retinoid cycle. Abnormalities in this cycle can compromise vision because of the diminished supply of 11-cis-retinal and the accumulation of toxic, constitutively active opsin. As shown previously for rod cells, attenuation of constitutively active opsin can be achieved with the unbleachable analogue, 11-cis-6-membered ring (11-cis-6mr)-retinal, which has therapeutic effects against certain degenerative retinal diseases...
May 9, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28487225/structural-and-functional-alterations-associated-with-deutan-n94k-and-r330q-mutations-of-green-cone-opsin
#16
Sundaramoorthy Srinivasan, Miguel A Fernández-Sampedro, Eva Ramon, Pere Garriga
Deuteranopia is an X-linked congenital dichromatic condition in which single point mutations in green cone opsin lead to defective non-functional cone photoreceptor cells. Green cone opsin belongs to the G protein-coupled receptor superfamily and consists of a seven transmembrane helical apoprotein covalently bound to 11-cis-retinal, by means of a protonated Schiff base linkage, in its inactive dark state. Several point mutations in green cone opsin have been reported to cause deuteranopia, but the structural details underlying the molecular mechanisms behind the malfunction of mutated opsins have not been clearly established...
May 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28484015/adaptation-of-cone-pigments-found-in-green-rods-for-scotopic-vision-through-a-single-amino-acid-mutation
#17
Keiichi Kojima, Yuki Matsutani, Takahiro Yamashita, Masataka Yanagawa, Yasushi Imamoto, Yumiko Yamano, Akimori Wada, Osamu Hisatomi, Kanto Nishikawa, Keisuke Sakurai, Yoshinori Shichida
Most vertebrate retinas contain a single type of rod for scotopic vision and multiple types of cones for photopic and color vision. The retinas of certain amphibian species uniquely contain two types of rods: red rods, which express rhodopsin, and green rods, which express a blue-sensitive cone pigment (M1/SWS2 group). Spontaneous activation of rhodopsin induced by thermal isomerization of the retinal chromophore has been suggested to contribute to the rod's background noise, which limits the visual threshold for scotopic vision...
May 8, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28483278/specific-visible-radiation-facilitates-lipolysis-in-mature-3t3-l1-adipocytes-via-rhodopsin-dependent-%C3%AE-3-adrenergic-signaling
#18
Phil June Park, Jae Youl Cho, Eun-Gyung Cho
The regulation of fat metabolism is important for maintaining functional and structural tissue homeostasis in biological systems. Reducing excessive lipids has been an important concern due to the concomitant health risks caused by metabolic disorders such as obesity, adiposity and dyslipidemia. A recent study revealed that unlike conventional care regimens (e.g., diet or medicine), low-energy visible radiation (VR) regulates lipid levels via autophagy-dependent hormone-sensitive lipase (HSL) phosphorylation in differentiated human adipose-derived stem cells...
April 27, 2017: European Journal of Cell Biology
https://www.readbyqxmd.com/read/28480968/the-influence-of-raav2-mediated-sox2-delivery-into-neonatal-and-adult-human-rpe-cells-a-comparative-study
#19
Razie Ezati, Azadeh Etemadzadeh, Zahra-Soheila Soheili, Shahram Samiei, Ehsan Ranaei Pirmardan, Malihe Davari, Hoda Shams Najafabadi
Cell replacement is a promising therapy for degenerative diseases like age-related macular degeneration (AMD). Since the human retina lacks regeneration capacity, much attention has been directed towards persuading for cells that can differentiate into retinal neurons. In this report we have investigated reprogramming of the human RPE cells and concerned the effect of donor age on the cellular fate as a critical determinant in reprograming competence. We evaluated the effect of SOX2 over-expression in human neonatal and adult RPE cells in cultures...
May 8, 2017: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/28477350/protonation-state-coupled-conformational-dynamics-in-reaction-mechanisms-of-channel-and-pump-rhodopsins
#20
Ana-Nicoleta Bondar, Jeremy C Smith
Channel and pump rhodopsins use energy from light absorbed by a covalently bound retinal chromophore to transport ions across membranes of microbial cells. Ion transfer steps, including proton transfer, can couple to changes in protein conformational dynamics and water positions. Although general principles of how microbial rhodopsins function are largely understood, key issues pertaining to reaction mechanisms remain unclear. In this review, we compare the protonation-coupled dynamics of pump and channel rhodopsins, highlighting the roles that water dynamics, protein electrostatics, and protein flexibility can have in ion transport mechanisms...
May 6, 2017: Photochemistry and Photobiology
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