Open AccessA two-lane mechanism for selective biological ammonium transport
Author(s) -
Gordon Williamson,
Gaëtan Dias Mirandela,
Giulia Tamburrino,
Mélanie Boeckstaens,
Adriana Bizior,
Eilidh Terras,
Marcus G Bage,
Callum M. Ives,
Andrei V. Pisliakov,
Anna María Marini,
Paul A. Hoskisson,
Ulrich Zachariae,
Arnaud Javelle
Publication year - 2020
Publication title -
access microbiology
Language(s) - English
Resource type - Journals
ISSN - 2516-8290
DOI - 10.1099/acmi.ac2020.po0133
Subject(s) - mechanism (biology) , deprotonation , chemistry , membrane , biophysics , complementation , transporter , substrate (aquarium) , ion transporter , ammonium , membrane transport protein , biological membrane , ion , biochemistry , mutant , biology , membrane protein , physics , ecology , gene , organic chemistry , quantum mechanics
The transport of charged molecules across biological membranes faces the dual problem of accommodating charges in a highly hydrophobic environment while maintaining selective substrate translocation. A particular controversy has existed around the mechanism of ammonium exchange by the ubiquitous Amt/Mep/Rh transporter family, an essential process in all kingdoms of life. Here, using a combination of SSME electrophysiology, yeast functional complementation, and extended molecular dynamics simulations, we reveal a unique two-lane pathway for electrogenic NH4+transport in two archetypal members of the family. The pathway underpins a mechanism by which charged H+and neutral NH3 are carried separately across the membrane after NH4+deprotonation. This mechanism defines a new principle of achieving transport selectivity against competing ions in a biological transport process.