6qxa

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== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
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Membrane-bound pyrophosphatases (M-PPases), which couple proton/sodium ion transport to pyrophosphate synthesis/hydrolysis, are important in abiotic stress resistance and in the infectivity of protozoan parasites. Here, three M-PPase structures in different catalytic states show that closure of the substrate-binding pocket by helices 5-6 affects helix 13 in the dimer interface and causes helix 12 to move down. This springs a 'molecular mousetrap', repositioning a conserved aspartate and activating the nucleophilic water. Corkscrew motion at helices 6 and 16 rearranges the key ionic gate residues and leads to ion pumping. The pumped ion is above the ion gate in one of the ion-bound structures, but below it in the other. Electrometric measurements show a single-turnover event with a non-hydrolysable inhibitor, supporting our model that ion pumping precedes hydrolysis. We propose a complete catalytic cycle for both proton and sodium-pumping M-PPases, and one that also explains the basis for ion specificity.
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Membrane-bound pyrophosphatases are homodimeric integral membrane proteins that hydrolyze pyrophosphate into orthophosphates, coupled to the active transport of protons or sodium ions across membranes. They are important in the life cycle of bacteria, archaea, plants, and parasitic protists, but no homologous proteins exist in vertebrates, making them a promising drug target. Here, we report the first nonphosphorus allosteric inhibitor of the thermophilic bacterium Thermotoga maritima membrane-bound pyrophosphatase and its bound structure together with the substrate analog imidodiphosphate. The unit cell contains two protein homodimers, each binding a single inhibitor dimer near the exit channel, creating a hydrophobic clamp that inhibits the movement of beta-strand 1-2 during pumping, and thus prevents the hydrophobic gate from opening. This asymmetry of inhibitor binding with respect to each homodimer provides the first clear structural demonstration of asymmetry in the catalytic cycle of membrane-bound pyrophosphatases.
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Membrane pyrophosphatases from Thermotoga maritima and Vigna radiata suggest a conserved coupling mechanism.,Li KM, Wilkinson C, Kellosalo J, Tsai JY, Kajander T, Jeuken LJ, Sun YJ, Goldman A Nat Commun. 2016 Dec 6;7:13596. doi: 10.1038/ncomms13596. PMID:27922000<ref>PMID:27922000</ref>
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Asymmetry in catalysis by Thermotoga maritima membrane-bound pyrophosphatase demonstrated by a nonphosphorus allosteric inhibitor.,Vidilaseris K, Kiriazis A, Turku A, Khattab A, Johansson NG, Leino TO, Kiuru PS, Boije Af Gennas G, Meri S, Yli-Kauhaluoma J, Xhaard H, Goldman A Sci Adv. 2019 May 22;5(5):eaav7574. doi: 10.1126/sciadv.aav7574. eCollection 2019, May. PMID:31131322<ref>PMID:31131322</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

Revision as of 23:14, 5 June 2019

Structure of membrane bound pyrophosphatase from Thermotoga maritima in complex with imidodiphosphate and N-[(2-amino-6-benzothiazolyl)methyl]-1H-indole-2-carboxamide (ATC)

PDB ID 6qxa

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