--- res: bibo_abstract: - Multiple resistance and pH adaptation (Mrp) antiporters are multi-subunit Na+ (or K+)/H+ exchangers representing an ancestor of many essential redox-driven proton pumps, such as respiratory complex I. The mechanism of coupling between ion or electron transfer and proton translocation in this large protein family is unknown. Here, we present the structure of the Mrp complex from Anoxybacillus flavithermus solved by cryo-EM at 3.0 Å resolution. It is a dimer of seven-subunit protomers with 50 trans-membrane helices each. Surface charge distribution within each monomer is remarkably asymmetric, revealing probable proton and sodium translocation pathways. On the basis of the structure we propose a mechanism where the coupling between sodium and proton translocation is facilitated by a series of electrostatic interactions between a cation and key charged residues. This mechanism is likely to be applicable to the entire family of redox proton pumps, where electron transfer to substrates replaces cation movements.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Julia foaf_name: Steiner, Julia foaf_surname: Steiner foaf_workInfoHomepage: http://www.librecat.org/personId=3BB67EB0-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0003-0493-3775 - foaf_Person: foaf_givenName: Leonid A foaf_name: Sazanov, Leonid A foaf_surname: Sazanov foaf_workInfoHomepage: http://www.librecat.org/personId=338D39FE-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-0977-7989 bibo_doi: 10.7554/eLife.59407 bibo_volume: 9 dct_date: 2020^xs_gYear dct_identifier: - UT:000562123600001 dct_isPartOf: - http://id.crossref.org/issn/2050084X dct_language: eng dct_publisher: eLife Sciences Publications@ dct_title: Structure and mechanism of the Mrp complex, an ancient cation/proton antiporter@ fabio_hasPubmedId: '32735215' ...