Abstract Phytoplankton is the base of the marine food chain, oxygen, carbon cycle playing a global role in climate and ecology. Nucleocytoplasmic Large DNA Viruses regulating the dynamics of phytoplankton comprise genes of rhodopsins of two distinct families. We present a function-structure characterization of two homologous proteins representatives of family 1 of viral rhodopsins, OLPVR1 and VirChR1. VirChR1 is a highly selective, Ca 2+ -dependent, Na + /K + - conducting channel and, in contrast to known cation channelrhodopsins (ChRs), is impermeable to Ca 2+ ions. In human neuroblastoma cells, upon illumination, VirChR1 depolarizes the cell membrane to a level sufficient to fire neurons. It suggests its unique optogenetic potential. 1.4 Å resolution structure of OLPVR1 reveals their remarkable difference from the known channelrhodopsins and a unique ion-conducting pathway. The data suggest that viral channelrhodopsins mediate phototaxis of algae enhancing the host anabolic processes to support virus reproduction, and therefore, their key role in global phytoplankton dynamics.
Roman Astashkin, Kirill Kovalev, Sergey Bukhdruker, S. Vaganova, Alexander Kuzmin, Alexey Alekseev, Taras Balandin, Dmitrii Zabelskii, Ivan Gushchin, Antoine Royant, D. Volkov, Gleb Bourenkov, Eugene V Koonin, Martin Engelhard, Ernst Bamberg, Valentin Gordeliy
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