9or2

Antarctic Rhodopsin crystallized in bicelles at pH 4.0

spinqualitylabelsall models 9or2, resolution 2.07Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9or2 is a 1 chain structure with sequence from Unidentified. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.07Å Ligands: 3PE, D12, RET Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Two phylogenetically distinct groups of microbial rhodopsins show light-induced inward proton transport activity, xenorhodopsins (XeRs) and schizorhodopsins (SzRs). However, structural insights into inward proton pumps are limited, as only three structures have been determined to date, Nanosalina xenorhodopsin (NsXeR), Bacillus coahuilensis xenorhodopsin (BcXeR), and Lokiarchaeota archaeon Schizorhodopsin-4 (SzR4). In contrast, numerous structures of outward proton-pumping rhodopsins are available, posing challenges for broad structure-function comparisons and limiting the study of structural variations among inward proton pumps. Here, we report the crystal structure of the light-driven inward proton pumping rhodopsin, Antarctic Rhodopsin (AntR), a representative member of the SzR group. As AntR displayed a pH-dependent retinal configuration, it was crystallized under acidic and basic conditions. The structures revealed short transmembrane alpha-helices and large water-filled cavities, which are similar to SzR4 and exceedingly different to NsXeR and BcXeR. AntR possesses a long C-terminal alpha-helix that extends into the cytoplasm to cover the proton conducting pathway, a feature which has not been observed in other microbial rhodopsins. Truncating this cytoplasmic alpha-helix results in decreased inward proton pumping efficiency. Integrating the structural and functional results with existing mutagenesis data, we propose a putative inward proton transport mechanism for AntR. The AntR structure provided insights into the conserved and distinctive characteristics of SzRs, highlighting structural variations from type I rhodopsins and heliorhodopsins. Structural insights into an inward proton pumping rhodopsin.,Besaw JE, Peng S, Kuo A, Reichenwallner J, Miller RJD, Brown LS, Ernst OP Biophys J. 2025 Nov 11:S0006-3495(25)00746-5. doi: 10.1016/j.bpj.2025.11.011. PMID:41229115 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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