An unusual twin: his arrangement in the pore of ammonia channels is essential for substrate conductance

Arnaud Javelle, Domenico Lupo, Lei Zheng, Xiao-Dan Li, Fritz K Winkler, Mike Merrick

    Research output: Contribution to journalArticlepeer-review

    56 Citations (Scopus)

    Abstract

    Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved histidine residues in the pore have been proposed to be necessary for ammonia conductance. By analyzing 14 engineered polar and non-polar variants of these histidines, in Escherichia coli AmtB, we show that both histidines are absolutely required for optimum substrate conductance. Crystal structures of variants confirm that substitution of the histidine residues does not affect AmtB structure. In a subgroup of Amt proteins, found only in fungi, one of the histidines is replaced by glutamate. The equivalent substitution in E. coli AmtB is partially active, and the structure of this variant suggests that the glutamate side chain can make similar interactions to those made by histidine.

    Original languageEnglish
    Pages (from-to)39492-8
    Number of pages7
    JournalJournal of Biological Chemistry
    Volume281
    Issue number51
    DOIs
    Publication statusPublished - 2006

    Fingerprint Dive into the research topics of 'An unusual twin: his arrangement in the pore of ammonia channels is essential for substrate conductance'. Together they form a unique fingerprint.

    Cite this