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Channelrhodopsin (ChR) functions as a light-gated ion channel in Chlamydomonas reinhardtii. Passive transport of cations by ChR is fundamentally different from the active transport by light-driven ion pumps such as archaerhodopsin, bacteriorhodopsin, and halorhodopsin. These microbial rhodopsins are important tools for optogenetics, where ChR is used to(More)
Light-driven outward H(+) pumps are widely distributed in nature, converting sunlight energy into proton motive force. Here we report the characterization of an oppositely directed H(+) pump with a similar architecture to outward pumps. A deep-ocean marine bacterium, Parvularcula oceani, contains three rhodopsins, one of which functions as a light-driven(More)
The recently identified Krokinobacter rhodopsin 2 (KR2) functions as a light-driven sodium ion pump. The structure of the retinal-binding pocket of KR2 offers important insights into the mechanisms of KR2, which has motif of Asn112, Asp116, and Gln123 (NDQ) that is common among sodium ion pump rhodopsins but is unique among other microbial rhodopsins. Here(More)
Light-driven H+, Na+ and Cl- pumps have been found in eubacteria, which convert light energy into a transmembrane electrochemical potential. A recent mutation study revealed asymmetric functional conversion between the two pumps, where successful functional conversions are achieved exclusively when mutagenesis reverses the evolutionary amino acid sequence(More)
One of the main functions of microbial rhodopsins is outward-directed light-driven proton transport across the plasma membrane, which can provide sources of energy alternative to respiration and chlorophyll photosynthesis. Proton-pumping rhodopsins are found in Archaea (Halobacteria), multiple groups of Bacteria, numerous fungi, and some microscopic algae.(More)
Parvularcula oceani xenorhodopsin (PoXeR) is a light-driven inward proton pump that was discovered from deep ocean marine bacteria. PoXeR is categorized into the same family of Anabaena sensory rhodopsin (ASR) that functions as a photochromic sensor. In this study, we applied light-induced difference Fourier-transform infrared (FTIR) spectroscopy to PoXeR(More)
Microbial rhodopsins are membrane proteins found widely in archaea, eubacteria and eukaryotes (fungal and algal species). They have various functions, such as light-driven ion pumps, light-gated ion channels, light sensors and light-activated enzymes. A light-driven proton pump bacteriorhodopsin (BR) contains a DTD motif at positions 85, 89, and 96, which(More)
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