| Autor: |
Li, K-M, Wilkinson, C, Kellosalo, J, Tsai, J-Y, Kajander, T, Jeuken, LJC, Sun, Y-J, Goldman, A |
| Jazyk: |
angličtina |
| Rok vydání: |
2016 |
| Zdroj: |
'Nature Communications ', vol: 7, pages: 13596-1-13596-11 (2016) |
| ISSN: |
2041-1723 |
| Popis: |
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-PPases 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. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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