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Marín MDC, Konno M, Yawo H, Inoue K. Converting a Natural-Light-Driven Outward Proton Pump Rhodopsin into an Artificial Inward Proton Pump. J Am Chem Soc 2023; 145:10938-10942. [PMID: 37083435 DOI: 10.1021/jacs.2c12602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Microbial rhodopsins are a large family of photoreceptive membrane proteins with diverse light-regulated functions. While the most ubiquitous microbial rhodopsins are light-driven outward proton (H+) pumps, new subfamilies of microbial rhodopsins transporting H+ inwardly, i.e., light-driven inward H+ pumps, have been discovered recently. Although structural and spectroscopic studies provide insights into their ion transport mechanisms, the minimum key element(s) that determine the direction of H+ transport have not yet been clarified. Here, we conducted the first functional conversion study by substituting key amino acids in a natural outward H+-pumping rhodopsin (PspR) with those in inward H+-pumping rhodopsins. Consequently, an artificial inward H+ pump was constructed by mutating only three residues of PspR. This result indicates that these residues govern the key processes that discriminate between outward and inward H+ pumps. Spectroscopic studies revealed the presence of an inward H+-accepting residue in the H+ transport pathway and direct H+ uptake from the extracellular solvent. This finding of the simple element for determining H+ transport would provide a new basis for understanding the concept of ion transport not only by microbial rhodopsins but also by other ion-pumping proteins.
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Affiliation(s)
- María Del Carmen Marín
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Hiromu Yawo
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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He S, Linz AM, Stevens SLR, Tran PQ, Moya-Flores F, Oyserman BO, Dwulit-Smith JR, Forest KT, McMahon KD. Diversity, distribution, and expression of opsin genes in freshwater lakes. Mol Ecol 2023; 32:2798-2817. [PMID: 36799010 DOI: 10.1111/mec.16891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 01/28/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023]
Abstract
Microbial rhodopsins are widely distributed in aquatic environments and may significantly contribute to phototrophy and energy budgets in global oceans. However, the study of freshwater rhodopsins has been largely limited. Here, we explored the diversity, ecological distribution, and expression of opsin genes that encode the apoproteins of type I rhodopsins in humic and clearwater lakes with contrasting physicochemical and optical characteristics. Using metagenomes and metagenome-assembled genomes, we recovered opsin genes from a wide range of taxa, mostly predicted to encode green light-absorbing proton pumps. Viral opsin and novel bacterial opsin clades were recovered. Opsin genes occurred more frequently in taxa from clearwater than from humic water, and opsins in some taxa have nontypical ion-pumping motifs that might be associated with physicochemical conditions of these two freshwater types. Analyses of the surface layer of 33 freshwater systems revealed an inverse correlation between opsin gene abundance and lake dissolved organic carbon (DOC). In humic water with high terrestrial DOC and light-absorbing humic substances, opsin gene abundance was low and dramatically declined within the first few meters, whereas the abundance remained relatively high along the bulk water column in clearwater lakes with low DOC, suggesting opsin gene distribution is influenced by lake optical properties and DOC. Gene expression analysis confirmed the significance of rhodopsin-based phototrophy in clearwater lakes and revealed different diel expressional patterns among major phyla. Overall, our analyses revealed freshwater opsin diversity, distribution and expression patterns, and suggested the significance of rhodopsin-based phototrophy in freshwater energy budgets, especially in clearwater lakes.
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Affiliation(s)
- Shaomei He
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Alexandra M Linz
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sarah L R Stevens
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Patricia Q Tran
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Francisco Moya-Flores
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ben O Oyserman
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jeffrey R Dwulit-Smith
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Program in Biophysics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Katrina T Forest
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Program in Biophysics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Katherine D McMahon
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Complete Genome of Sphingomonas aerolata PDD-32b-11, Isolated from Cloud Water at the Summit of Puy de Dôme, France. Microbiol Resour Announc 2022; 11:e0068422. [PMID: 36106890 PMCID: PMC9584328 DOI: 10.1128/mra.00684-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The complete genome of
Sphingomonas aerolata
PDD-32b-11, a bacterium isolated from cloud water, was sequenced. It features four circular replicons, a chromosome of 3.99 Mbp, and three plasmids. Two putative rhodopsin-encoding genes were detected which might act as proton pumps to harvest light energy.
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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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