Structure and mechanism of an amino acid antiporter

Xiang Gao, Feiran Lu, Lijun Zhou, Shangyu Dang, Linfeng Sun, Xiaochun Li, Jiawei Wang, Yigong Shi

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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.

Original languageEnglish (US)
Pages (from-to)1565-1568
Number of pages4
JournalScience
Volume324
Issue number5934
DOIs
Publication statusPublished - Jun 19 2009

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Gao, X., Lu, F., Zhou, L., Dang, S., Sun, L., Li, X., ... Shi, Y. (2009). Structure and mechanism of an amino acid antiporter. Science, 324(5934), 1565-1568. https://doi.org/10.1126/science.1173654