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bioRxiv · 10.1101/767665

High Resolution Structural Insights into Heliorhodopsin Family

Kovalev, K.·Volkov, D.·Astashkin, R.·Alekseev, A.·Gushchin, I.·Haro-Moreno, J.·Rogachev, A.·Balandin, T.·Borshchevskiy, V.·Popov, A.·Bourenkov, G.·Bamberg, E.·Rodriguez-Valera, F.·Bueldt, G.·Gordeliy, V.
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Abstract

Rhodopsins are the most abundant light-harvesting proteins. A new family of rhodopsins, heliorhodopsins (HeRs), was recently discovered. In opposite to the known rhodopsins their N-termini face the cytoplasm. HeRs structure and function remain unknown. We present structures of two HeR-48C12 states at 1.5 [A] showing its remarkable difference from all known rhodopsins. Its internal extracellular part is completely hydrophobic, while the cytoplasmic part comprises a cavity (active site), surrounded by charged amino acids and containing a cluster of water molecules, presumably being a primary proton acceptor from the Schiff base. At acidic pH a planar triangle molecule (acetate) is present in the active site which demonstrated its ability to maintain such anions as carbonate or nitrate. Structure-based bioinformatic analysis identified 10 subfamilies of HeRs suggesting their diverse biological functions. The structures and available data suggest an enzymatic activity of HeR-48C12 subfamily and their possible involvement into fundamental redox biological processes.

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Kovalev, K., Volkov, D., Astashkin, R., Alekseev, A., Gushchin, I., Haro-Moreno, J., Rogachev, A., Balandin, T., Borshchevskiy, V., Popov, A., Bourenkov, G., Bamberg, E., Rodriguez-Valera, F., Bueldt, G., Gordeliy, V.. 2019-09-12. High Resolution Structural Insights into Heliorhodopsin Family. https://doi.org/10.1101/767665

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