Current submillisecond time-resolved broad-band infrared spectroscopy, one of the most frequently used techniques for studying structure-function relationships in life sciences, is typically limited to fast-cycling reactions that can be repeated thousands of times with high frequency. Notably, a majority of chemical and biological processes do not comply with this requirement. For example, the activation of vertebrate rhodopsin, a prototype of many protein receptors in biological organisms that mediate basic functions of life, including vision, smell, and taste, is irreversible. Here we present a dispersive single-shot Féry spectrometer setup that extends such spectroscopy to irreversible and slow-cycling systems by exploiting the unique properties of brilliant synchrotron infrared light combined with an advanced focal plane detector array embedded in a dispersive optical concept. We demonstrate our single-shot method on microbial actinorhodopsin with a slow photocycle and on vertebrate rhodopsin with irreversible activation.
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http://dx.doi.org/10.1021/acs.jpclett.9b03099 | DOI Listing |
J Struct Biol
January 2025
Gavin Herbert Eye Institute - Center for Translational Vision Research, Department of Ophthalmology, University of California, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. Electronic address:
Arrestins halt cell signaling by binding to phosphorylated activated G protein-coupled receptors. Arrestin-1 binds to rhodopsin, arrestin-4 binds to cone opsins, and arrestins-2,3 bind to the rest of GPCRs. In addition, it has been reported that arrestin-1 is functionally expressed in mouse cone photoreceptors.
View Article and Find Full Text PDFInt J Mol Sci
January 2025
Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
Sequences and three-dimensional structures of the four vertebrate arrestins are very similar, yet in sharp contrast to other subtypes, arrestin-1 demonstrates exquisite selectivity for the active phosphorylated form of its cognate receptor, rhodopsin. The N-terminus participates in receptor binding and serves as the anchor of the C-terminus, the release of which facilitates arrestin transition into a receptor-binding state. We tested the effects of substitutions of fourteen residues in the N-terminus of arrestin-1 on the binding to phosphorylated and unphosphorylated light-activated rhodopsin of wild-type protein and its enhanced mutant with C-terminal deletion that demonstrates higher binding to both functional forms of rhodopsin.
View Article and Find Full Text PDFNat Commun
January 2025
Center for Life Sciences, Yunnan Key Laboratory of Cell Metabolism and Diseases, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Life Sciences, Yunnan University, Kunming, China.
Phosphorus in crucial for all living organisms. In vertebrate, cellular phosphate homeostasis is partly controlled by XPR1, a poorly characterized inositol pyrophosphate-dependent phosphate exporter. Here, we report the cryo-EM structure of human XPR1, which forms a loose dimer with 10 transmembrane helices (TM) in each protomer.
View Article and Find Full Text PDFPLoS Biol
January 2025
Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America.
Pathogenic mutations that cause rhodopsin misfolding lead to a spectrum of currently untreatable blinding diseases collectively termed retinitis pigmentosa. Small molecules to correct rhodopsin misfolding are therefore urgently needed. In this study, we utilized virtual screening to search for drug-like molecules that bind to the orthosteric site of rod opsin and improve its folding and trafficking.
View Article and Find Full Text PDFJ Vis Exp
December 2024
Department of Ophthalmology and Visual Neurosciences, University of Minnesota;
G protein-coupled receptors (GPCRs) are a superfamily of transmembrane proteins that initiate signaling cascades through activation of its G protein upon association with its ligand. In all mammalian vision, rhodopsin is the GPCR responsible for the initiation of the phototransduction cascade. Within photoreceptors, rhodopsin is bound to its chromophore 11-cis-retinal and is activated through the light-sensitive isomerization of 11-cis-retinal to all-trans-retinal, which activates the transducin G protein, resulting in the phototransduction cascade.
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