A two-lane mechanism for selective biological ammonium transport

Elife. 2020 Jul 14;9:e57183. doi: 10.7554/eLife.57183.


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. This has been the subject of a particular controversy for the exchange of ammonium across cellular membranes, an essential process in all domains of life. Ammonium transport is mediated by the ubiquitous Amt/Mep/Rh transporters that includes the human Rhesus factors. Here, using a combination of 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 transporters AmtB from Escherichia coli and Rh50 from Nitrosomonas europaea. 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.

Keywords: E. coli; SSME; Saccharomyces cerevisiae; ammonium transporter; biochemistry; chemical biology; nitrosomonas europaea; rhesus protein; transport selectivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonia / metabolism*
  • Ammonium Compounds / metabolism*
  • Escherichia coli / metabolism*
  • Ion Transport*
  • Nitrosomonas europaea / metabolism*


  • Ammonium Compounds
  • Ammonia

Associated data

  • figshare/10.6084/m9.figshare.12826316