Roles of the Hydrophobic Gate and Exit Channel in Vigna radiata Pyrophosphatase Ion Translocation.Tsai, J.Y., Tang, K.Z., Li, K.M., Hsu, B.L., Chiang, Y.W., Goldman, A., Sun, Y.J.
(2019) J Mol Biol 431: 1619-1632
- PubMed: 30878480
- DOI: 10.1016/j.jmb.2019.03.009
- Primary Citation of Related Structures:
6AFT, 6AFS, 6AFV, 6AFU, 6AFX, 6AFW, 6AFZ, 6AFY
- PubMed Abstract:
Membrane-embedded pyrophosphatase (M-PPase) hydrolyzes pyrophosphate to drive ion (H + and/or Na + ) translocation. We determined crystal structures and functions of Vigna radiata M-PPase (VrH + -PPase), the VrH
Membrane-embedded pyrophosphatase (M-PPase) hydrolyzes pyrophosphate to drive ion (H + and/or Na + ) translocation. We determined crystal structures and functions of Vigna radiata M-PPase (VrH + -PPase), the VrH + -PPase-2P i complex and mutants at hydrophobic gate (residue L555) and exit channel (residues T228 and E225). Ion pore diameters along the translocation pathway of three VrH + -PPases complexes (P i -, 2P i - and imidodiphosphate-bound states) present a unique wave-like profile, with different pore diameters at the hydrophobic gate and exit channel, indicating that the ligands induced pore size alterations. The 2P i -bound state with the largest pore diameter might mimic the hydrophobic gate open. In mutant structures, ordered waters detected at the hydrophobic gate among VrH + -PPase imply the possibility of solvation, and numerous waters at the exit channel might signify an open channel. A salt-bridge, E225-R562 is at the way out of the exit channel of VrH + -PPase; E225A mutant makes the interaction eliminated and reveals a decreased pumping ability. E225-R562 might act as a latch to regulate proton release. A water wire from the ion gate (R-D-K-E) through the hydrophobic gate and into the exit channel may reflect the path of proton transfer.
Department of Life Science and Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu 30013, Taiwan. Electronic address: email@example.com.