Report

Structure and Mechanism of an Amino Acid Antiporter

See allHide authors and affiliations

Science  19 Jun 2009:
Vol. 324, Issue 5934, pp. 1565-1568
DOI: 10.1126/science.1173654

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Abstract

Virulent enteric pathogens such as Escherichia coli strain O157:H7 rely on acid-resistance (AR) systems to survive the acidic environment in the stomach. A major component of AR is an arginine-dependent arginine:agmatine antiporter that expels intracellular protons. Here, we report the crystal structure of AdiC, the arginine:agmatine antiporter from E. coli O157:H7 and a member of the amino acid/polyamine/organocation (APC) superfamily of transporters at 3.6 Å resolution. The overall fold is similar to that of several Na+-coupled symporters. AdiC contains 12 transmembrane segments, forms a homodimer, and exists in an outward-facing, open conformation in the crystals. A conserved, acidic pocket opens to the periplasm. Structural and biochemical analysis reveals the essential ligand-binding residues, defines the transport route, and suggests a conserved mechanism for the antiporter activity.

  • * These authors contributed equally to this work.

View Full Text