3l1l

Structure of Arg-bound Escherichia coli AdiC

spinqualitylabelsall models 3l1l, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3l1l is a 1 chain structure with sequence from Escherichia coli O157:H7. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.002Å Ligands: ARG, BNG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function ADIC_ECO57 Major component of the acid-resistance (AR) system allowing enteric pathogens to survive the acidic environment in the stomach. Exchanges extracellular arginine for its intracellular decarboxylation product agmatine (Agm) thereby expelling intracellular protons. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed In extremely acidic environments, enteric bacteria such as Escherichia coli rely on the amino acid antiporter AdiC to expel protons by exchanging intracellular agmatine (Agm(2+)) for extracellular arginine (Arg(+)). AdiC is a representative member of the amino acid-polyamine-organocation (APC) superfamily of membrane transporters. The structure of substrate-free AdiC revealed a homodimeric assembly, with each protomer containing 12 transmembrane segments and existing in an outward-open conformation. The overall folding of AdiC is similar to that of the Na(+)-coupled symporters. Despite these advances, it remains unclear how the substrate (arginine or agmatine) is recognized and transported by AdiC. Here we report the crystal structure of an E. coli AdiC variant bound to Arg at 3.0 A resolution. The positively charged Arg is enclosed in an acidic binding chamber, with the head groups of Arg hydrogen-bonded to main chain atoms of AdiC and the aliphatic portion of Arg stacked by hydrophobic side chains of highly conserved residues. Arg binding induces pronounced structural rearrangement in transmembrane helix 6 (TM6) and, to a lesser extent, TM2 and TM10, resulting in an occluded conformation. Structural analysis identified three potential gates, involving four aromatic residues and Glu 208, which may work in concert to differentially regulate the upload and release of Arg and Agm. Mechanism of substrate recognition and transport by an amino acid antiporter.,Gao X, Zhou L, Jiao X, Lu F, Yan C, Zeng X, Wang J, Shi Y Nature. 2010 Feb 11;463(7282):828-32. Epub 2010 Jan 20. PMID:20090677 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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