Read by QxMD icon Read


Tilman Kottke, Aihua Xie, Delmar S Larsen, Wouter D Hoff
The first stage in biological signaling is based on changes in the functional state of a receptor protein triggered by interaction of the receptor with its ligand(s). The light-triggered nature of photoreceptors allows studies on the mechanism of such changes in receptor proteins using a wide range of biophysical methods and with superb time resolution. Here, we critically evaluate current understanding of proton and electron transfer in photosensory proteins and their involvement both in primary photochemistry and subsequent processes that lead to the formation of the signaling state...
March 14, 2018: Annual Review of Biophysics
Arisu Shigeta, Shota Ito, Rina Kaneko, Sahoko Tomida, Keiichi Inoue, Hideki Kandori, Izuru Kawamura
Krokinobacter rhodopsin 2 (KR2), a light-driven Na+ pump, is a dual-functional protein, pumping protons in the absence of Na+ when K+ or larger alkali metal ions are present. A specific mutation in helix A near the extracellular Na+ binding site, H30A, eliminates its proton pumping ability. We induced structural changes in H30A by altering the alkali metal ion bound at the extracellular binding site, and observed a strong electrostatic interaction between the Schiff base and counterion and torsion around the Schiff base as revealed by solid-state nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies...
March 14, 2018: Physical Chemistry Chemical Physics: PCCP
Yan Xia, Axel W Fischer, Pedro Teixeira, Brian Weiner, Jens Meiler
While great progress has been made, only 10% of the nearly 1,000 integral, α-helical, multi-span membrane protein families are represented by at least one experimentally determined structure in the PDB. Previously, we developed the algorithm BCL::MP-Fold, which samples the large conformational space of membrane proteins de novo by assembling predicted secondary structure elements guided by knowledge-based potentials. Here, we present a case study of rhodopsin fold determination by integrating sparse and/or low-resolution restraints from multiple experimental techniques including electron microscopy, electron paramagnetic resonance spectroscopy, and nuclear magnetic resonance spectroscopy...
February 23, 2018: Structure
Natsuki Monai, Kodai Yamauchi, Reiko Tanabu, Takayuki Gonome, Sei-Ichi Ishiguro, Mitsuru Nakazawa
PURPOSE: To characterize the optical coherence tomography (OCT) appearances of photoreceptor degeneration in the rhodopsin P23H transgenic rat (line 2) in relation to the histological, ultrastructural, and electroretinography (ERG) findings. MATERIALS AND METHODS: Homozygous rhodopsin P23H transgenic albino rats (line 2, very-slow degeneration model) were employed. Using OCT (Micron IV®; Phoenix Research Labs, Pleasanton, CA, USA), the natural course of photoreceptor degeneration was recorded from postnatal day (P) 15 to P 287...
2018: PloS One
Hideki Kandori, Keiichi Inoue, Satoshi P Tsunoda
Ion pumps perform active transport of ions by using energy. The active transport mechanism can be illustrated by the Panama Canal model, which considers two gates and a gain in energy. The Panama Canal model is consistent with the alternating access model that is used to describe active transport, in which the substrate ion is bound, energized, and released. It was generally accepted that energization occurs only for an ion-bound protein but not for an ion-unbound protein. Light-driven proton and chloride pumps, two of the best studied pumps, are represented by the Panama Canal model...
March 7, 2018: Chemical Reviews
Gang Dai, Xiong Geng, Luomeng Chao, Jun Tamogami, Takashi Kikukawa, Makoto Demura, Naoki Kamo, Tatsuo Iwasa
Aspartic acid 103 (D103) of sensory rhodopsin II from Halobacterium salinarum (HsSRII, or also called phoborhodopsin) corresponds to D115 of bacteriorhodopsin (BR). This amino acid residue is functionally important in BR. The present work reveals that a substitution of D103 with asparagine (D103N) or glutamic acid (D103E) can cause large changes in HsSRII photocycle. These changes include (1) shortened lifetime of the M intermediate in the following order: the wild-type > D103N > D103E; (2) altered decay pathway of a 13-cis O-like species...
March 7, 2018: Photochemistry and Photobiology
Hongfeng Zhao, Junxia Jiang, Gang Wang, Chong Le, John C Wingfield
Extra-retinal, non-pineal, encephalic photoreceptors (EP) play important roles in mediating development of the reproductive system by the annual change in day length (photoperiodic gonadal response - PGR) in birds. However, the distribution of rhodopsin-like EPs and their functional daily, circadian and seasonal changes are still unclear in the avian brain. This study identifies two novel groups of rhodopsin-immunoreactive cells in the nucleus paraventricularis magnocellularis (PVN) of the hypothalamus and in the medial basal hypothalamus (MBH) in a seasonally breeding species, Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii)...
March 3, 2018: Brain Research
Philip D Kiser, Jianye Zhang, Aditya Sharma, Juan M Angueyra, Alexander V Kolesnikov, Mohsen Badiee, Gregory P Tochtrop, Junzo Kinoshita, Neal S Peachey, Wei Li, Vladimir J Kefalov, Krzysztof Palczewski
Visual function in vertebrates critically depends on the continuous regeneration of visual pigments in rod and cone photoreceptors. RPE65 is a well-established retinoid isomerase in the pigment epithelium that regenerates rhodopsin during the rod visual cycle; however, its contribution to the regeneration of cone pigments remains obscure. In this study, we use potent and selective RPE65 inhibitors in rod- and cone-dominant animal models to discern the role of this enzyme in cone-mediated vision. We confirm that retinylamine and emixustat-family compounds selectively inhibit RPE65 over DES1, the putative retinoid isomerase of the intraretinal visual cycle...
March 2, 2018: Journal of General Physiology
Yuehui Tian, Shiqiang Gao, Shang Yang, Georg Nagel
It is since many years textbook knowledge that the concentration of the second messenger cGMP is regulated in animal rod and cone cells by type-II rhodopsins via a G protein signaling cascade. Microbial rhodopsins with enzymatic activity for regulation of cGMP concentration were only recently discovered: in 2014 light-activated guanylyl cyclase opsins in fungi and in 2017 a novel rhodopsin phosphodiesterase in the protist Salpingoeca rosetta ( Sr RhoPDE). The light-regulation of Sr RhoPDE however, seemed very weak or absent...
February 26, 2018: Biochemical Journal
Takashi Nagata, Mitsumasa Koyanagi, Robert Lucas, Akihisa Terakita
Peropsin or retinal pigment epithelium-derived rhodopsin homolog, found in many animals, belongs to the opsin family. Most opsins bind to 11-cis-retinal as a chromophore and act as light-activated G protein-coupled receptors. Some peropsins, however, bind all-trans-retinal and isomerise it into 11-cis form by light, and peropsin has been suggested to supply other visual opsins with 11-cis-retinal. Additionally, peropsin has some amino acid sequence motifs that are highly conserved among G protein-coupled opsins...
February 23, 2018: Scientific Reports
Paul McVeigh, Erin McCammick, Paul McCusker, Duncan Wells, Jane Hodgkinson, Steve Paterson, Angela Mousley, Nikki J Marks, Aaron G Maule
G protein-coupled receptors (GPCRs) are established drug targets. Despite their considerable appeal as targets for next-generation anthelmintics, poor understanding of their diversity and function in parasitic helminths has thwarted progress towards GPCR-targeted anti-parasite drugs. This study facilitates GPCR research in the liver fluke, Fasciola hepatica, by generating the first profile of GPCRs from the F. hepatica genome. Our dataset describes 147 high confidence GPCRs, representing the largest cohort of GPCRs, and the largest set of in silico ligand-receptor predictions, yet reported in any parasitic helminth...
February 5, 2018: International Journal for Parasitology, Drugs and Drug Resistance
Hyun Aaron Kim, Hyun Ju Kim, Min Ju Lee, Jihoon Park, Ah Reum Choi, Haeyoung Jeong, Kwang-Hwan Jung, Pil Kim, Sang Jun Lee
We reported that the phototrophic metabolism via plasmid-originated Gloeobacter rhodopsin(GR)-expression is improved in Escherichia coli ET5 harboring pKJ606-GR by a genomic point mutation (dgcQC1082A ) encoding a transmembrane cell signaling protein (Microb. Cell Fact. 16:111, 2017). Another evolved descendant was isolated from the chemostat, and the genome variation of the strain named ET8 harboring pKJ606-GR was investigated in this study. Whole genome sequencing analysis identified a single point mutation (C3831976A) located in the non-coding upstream region of kdtA and an IS4 insertional mutation at galUG706 without any mutations in the plasmid...
February 22, 2018: Biotechnology Journal
Marko Ilić, Andrej Meglič, Marko Kreft, Gregor Belušič
Microvillar photoreceptors are intrinsically capable of detecting the orientation of e-vector of linearly polarized light. They provide most invertebrates with an additional sensory channel to detect important features of their visual environment. However, polarization sensitivity (PS) of photoreceptors may lead to the detection of polarization-induced false colors and intensity contrasts. Most insect photoreceptors are thus adapted to have minimal PS. Flies have twisted rhabdomeres with microvilli rotated along the length of the ommatidia to reduce PS...
2018: Frontiers in Cellular Neuroscience
Jonathan Rolland, Daniele Silvestro, Glenn Litsios, Laurélène Faye, Nicolas Salamin
The difference between rapid morphological evolutionary changes observed in populations and the long periods of stasis detected in the fossil record has raised a decade-long debate about the exact role played by intraspecific mechanisms at the interspecific level. Although they represent different scales of the same evolutionary process, micro- and macroevolution are rarely studied together and few empirical studies have compared the rates of evolution and the selective pressures between both scales. Here, we analyse morphological, genetic and ecological traits in clownfishes at different evolutionary scales and demonstrate that the tempo of molecular and morphological evolution at the species level can be, to some extent, predicted from parameters estimated below the species level, such as the effective population size or the rate of evolution within populations...
February 28, 2018: Proceedings. Biological Sciences
Ivan Gushchin, Valentin Gordeliy
Microbial rhodopsins (MRs) are a large family of photoactive membrane proteins, found in microorganisms belonging to all kingdoms of life, with new members being constantly discovered. Among the MRs are light-driven proton, cation and anion pumps, light-gated cation and anion channels, and various photoreceptors. Due to their abundance and amenability to studies, MRs served as model systems for a great variety of biophysical techniques, and recently found a great application as optogenetic tools. While the basic aspects of microbial rhodopsins functioning have been known for some time, there is still a plenty of unanswered questions...
2018: Sub-cellular Biochemistry
Katie L Bales, Lara Ianov, Andrew J Kennedy, J David Sweatt, Alecia K Gross
Purpose: Epigenetic and transcriptional mechanisms have been shown to contribute to long-lasting functional changes in adult neurons. The purpose of this study was to identify any such modifications in diseased retinal tissues from a mouse model of rhodopsin mutation-associated autosomal dominant retinitis pigmentosa (ADRP), Q344X, relative to age-matched wild-type (WT) controls. Methods: We performed RNA sequencing (RNA-seq) at poly(A) selected RNA to profile the transcriptional patterns in 3-week-old ADRP mouse model rhodopsin Q344X compared to WT controls...
2018: Molecular Vision
Ned Van Eps, Christian Altenbach, Lydia N Caro, Naomi R Latorraca, Scott A Hollingsworth, Ron O Dror, Oliver P Ernst, Wayne L Hubbell
More than two decades ago, the activation mechanism for the membrane-bound photoreceptor and prototypical G protein-coupled receptor (GPCR) rhodopsin was uncovered. Upon light-induced changes in ligand-receptor interaction, movement of specific transmembrane helices within the receptor opens a crevice at the cytoplasmic surface, allowing for coupling of heterotrimeric guanine nucleotide-binding proteins (G proteins). The general features of this activation mechanism are conserved across the GPCR superfamily...
February 20, 2018: Proceedings of the National Academy of Sciences of the United States of America
E Lobysheva, C M Taylor, G R Marshall, O G Kisselev
The heterotrimeric G-protein binding site on G-protein coupled receptors remains relatively unexplored regarding its potential as a new target of therapeutic intervention or as a secondary site of action by the existing drugs. Tauroursodeoxycholic acid bears structural resemblance to several compounds that were previously identified to specifically bind to the light-activated form of the visual receptor rhodopsin and to inhibit its activation of transducin. We show that TUDCA stabilizes the active form of rhodopsin, metarhodopsin II, and does not display the detergent-like effects of common amphiphilic compounds that share the cholesterol scaffold structure, such as deoxycholic acid...
February 15, 2018: Experimental Eye Research
Ting Su, Yisheng Zhong, Anna M Demetriades, Jikui Shen, Ailing Sui, Yiyun Yao, Yushuo Gao, Yanji Zhu, Xi Shen, Bing Xie
Purpose: Ocular neovascularization (NV) is a pathologic process characterized by the proliferation and infiltration of various types of cells such as RPE, glial, and endothelial cells, which interact with proangiogenic factors and inflammatory cytokines. Endocan is known to be enriched in retinal endothelial tip cells under hypoxia, but the effect of endocan on ocular NV progression is largely unknown. In this study, we investigated the role of endocan in the ocular NV pathologic process and the possible mechanisms involved...
February 1, 2018: Investigative Ophthalmology & Visual Science
Lifu Xiao, Abdul K Parchur, Timothy A Gilbertson, Anhong Zhou
G-protein-coupled receptor 120 (GPR120), as a member of the rhodopsin family of G-protein-coupled receptors, has been shown to function as a sensor for dietary fat in the gustatory and digestive systems. Its specific role in the chemoreception of fatty acids, which is thought to be crucial in understanding the mechanism surrounding the control of fat intake and, accordingly, in the treatment of obesity, remains unclear. Here we report a novel surface-enhanced Raman spectroscopy (SERS)-fluorescence bimodal microscopic technique for detection and imaging of GPR120 in single living cells...
2018: Analytical Methods: Advancing Methods and Applications
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"