The mechanism of ammonia transport based on the crystal structure of AmtB of Escherichia coli.

ABSTRACT: Ammonium is one of the most important nitrogen sources for bacteria, fungi, and plants, but it is toxic to animals. The ammonium transport proteins (methylamine permeases/ammonium transporters/rhesus) are present in all domains of life; however, functional studies with members of this family have yielded controversial results with respect to the chemical identity (NH(4)(+) or NH(3)) of the transported species. We have solved the structure of wild-type AmtB from Escherichia coli in two crystal forms at 1.8- and 2.1-A resolution, respectively. Substrate transport occurs through a narrow mainly hydrophobic pore located at the center of each monomer of the trimeric AmtB. At the periplasmic entry, a binding site for NH(4)(+) is observed. Two phenylalanine side chains (F107 and F215) block acces

SUBMITTER: Zheng L 

PROVIDER: S-EPMC535379 | biostudies-literature | 2004 Dec

REPOSITORIES: biostudies-literature