Membrane pyrophosphatases from Thermotoga maritima and Vigna radiata suggest a conserved coupling mechanism

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Li , K-M , Wilkinson , C , Kellosalo , J , Tsai , J-Y , Kajander , T , Jeuken , L J C , Sun , Y-J & Goldman , A 2016 , ' Membrane pyrophosphatases from Thermotoga maritima and Vigna radiata suggest a conserved coupling mechanism ' , Nature Communications , vol. 7 , 13596 . https://doi.org/10.1038/ncomms13596

Title: Membrane pyrophosphatases from Thermotoga maritima and Vigna radiata suggest a conserved coupling mechanism
Author: Li, Kun-Mou; Wilkinson, Craig; Kellosalo, Juho; Tsai, Jia-Yin; Kajander, Tommi; Jeuken, Lars J. C.; Sun, Yuh-Ju; Goldman, Adrian
Contributor: University of Helsinki, Institute of Biotechnology
University of Helsinki, Institute of Biotechnology
University of Helsinki, Biosciences
Date: 2016-12-06
Language: eng
Number of pages: 11
Belongs to series: Nature Communications
ISSN: 2041-1723
URI: http://hdl.handle.net/10138/172747
Abstract: 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.
Subject: VACUOLAR H+-PYROPHOSPHATASE
PUMPING PYROPHOSPHATASE
CRYSTAL-STRUCTURE
ROTARY MECHANISM
NA+
SODIUM
PROTEINS
TRANSLOCATION
PURIFICATION
TRANSPORT
1182 Biochemistry, cell and molecular biology
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