Ammonium Transporters Achieve Charge Transfer by Fragmenting Their Substrate
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
 
ID 1202689
Author(s) Wang, Shihao; Orabi, Esam A; Baday, Sefer; Bernèche, Simon; Lamoureux, Guillaume
Author(s) at UniBasel Bernèche, Simon
Year 2012
Title Ammonium Transporters Achieve Charge Transfer by Fragmenting Their Substrate
Journal Journal of the American Chemical Society
Volume 134
Number 25
Pages / Article-Number 10419-27
Abstract

Proteins of the Amt/MEP family facilitate ammonium transport across the membranes of plants, fungi, and bacteria, and are essential for growth in nitrogen-poor environments. Some are known to facilitate the diffusion of the neutral NH3 while others, notably in plants, transport the positively charged NH4+. Based on the structural data for AmtB from Escherichia coli, we illustrate the mechanism by which proteins from the Amt family can sustain electrogenic transport. Free energy calculations show that NH4+ is stable in the AmtB pore, reaching a binding site from which it can spontaneously transfer a proton to a pore-lining histidine residue (His168). The substrate diffuses down the pore in the form of NH3 while the excess proton is co-transported through a highly conserved hydrogen-bonded His168-His318 pair. This constitutes a novel permeation mechanism that confers to the histidine dyad an essential mechanistic role that was so far unknown.

Publisher American Chemical Society
ISSN/ISBN 0002-7863
edoc-URL http://edoc.unibas.ch/dok/A6043625
Full Text on edoc No
Digital Object Identifier DOI 10.1021/ja300129x
PubMed ID http://www.ncbi.nlm.nih.gov/pubmed/22631217
ISI-Number WOS:000305716700026
Document type (ISI) Journal Article
 
   

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