| Structural highlights
Function
AVP_VIGRR Proton-translocating inorganic pyrophosphatase that contributes to the transtonoplast (from cytosol to vacuole lumen) H(+)-electrochemical potential difference. It establishes a proton gradient of similar and often greater magnitude than the H(+)-ATPase on the same membrane.[1] [2] [3] [4]
Publication Abstract from PubMed
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.
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[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Yang SJ, Jiang SS, Kuo SY, Hung SH, Tam MF, Pan RL. Localization of a carboxylic residue possibly involved in the inhibition of vacuolar H+-pyrophosphatase by N, N'-dicyclohexylcarbodi-imide. Biochem J. 1999 Sep 15;342 Pt 3:641-6. PMID:10477275
- ↑ Lin SM, Tsai JY, Hsiao CD, Huang YT, Chiu CL, Liu MH, Tung JY, Liu TH, Pan RL, Sun YJ. Crystal structure of a membrane-embedded H+-translocating pyrophosphatase. Nature. 2012 Mar 28;484(7394):399-403. doi: 10.1038/nature10963. PMID:22456709 doi:10.1038/nature10963
- ↑ Maeshima M, Yoshida S. Purification and properties of vacuolar membrane proton-translocating inorganic pyrophosphatase from mung bean. J Biol Chem. 1989 Nov 25;264(33):20068-73. PMID:2555340
- ↑ Nakanishi Y, Maeshima M. Molecular cloning of vacuolar H(+)-pyrophosphatase and its developmental expression in growing hypocotyl of mung bean. Plant Physiol. 1998 Feb;116(2):589-97. PMID:9489011
- ↑ Li KM, Wilkinson C, Kellosalo J, Tsai JY, Kajander T, Jeuken LJ, Sun YJ, Goldman A. Membrane pyrophosphatases from Thermotoga maritima and Vigna radiata suggest a conserved coupling mechanism. Nat Commun. 2016 Dec 6;7:13596. doi: 10.1038/ncomms13596. PMID:27922000 doi:http://dx.doi.org/10.1038/ncomms13596
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