Open AccessCrystal structure of schizorhodopsin reveals mechanism of inward proton pumping
Author(s) -
Akimitsu Higuchi,
Wataru Shihoya,
Masae Konno,
Tatsuya Ikuta,
Hideki Kandori,
Kazuhide Inoue,
Osamu Nureki
Publication year - 2021
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.2016328118
Subject(s) - archaea , rhodopsin , bacteriorhodopsin , transmembrane protein , biophysics , biology , cytoplasm , cytosol , convergent evolution , bacteria , biochemistry , crystallography , chemistry , membrane , genetics , enzyme , phylogenetics , gene , receptor , retinal
Significance We present a high-resolution structure of schizorhodopsin (SzR), a new rhodopsin family identified in Asgard archaea. SzRs work as light-driven inward H+ pumps as bacterial xenorhodopsins. Although SzRs are phylogenetically located at an intermediate position between type-1 microbial rhodopsins and heliorhodopsins, the structure of SzR resembles that of bacteriorhodopsin. Notably, the cytoplasmic parts of the transmembrane helices in SzR are shorter than those in other microbial rhodopsin, and thus the putative H+ acceptor E81 is located near the cytosol. Thus, we propose a model of untrapped inward H+ release through a water-mediated transport network, which is different from xenorhodopsins, suggesting essential insights into the convergent evolution of the same molecular function in Asgard archaea and bacteria.