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Abstract The influenza B M2 protein forms a water-filled tetrameric channel to conduct protons across the lipid membrane. To understand how channel water mediates proton transport, we have investigated the water orientation and dynamics using solid-state NMR spectroscopy and molecular dynamics (MD) simulations. 13 C-detected water 1 H NMR relaxation times indicate that water has faster rotational motion in the low-pH open channel than in the high-pH closed channel. Despite this faster dynamics, the open-channel water shows higher orientational order, as manifested by larger motionally-averaged 1 H chemical shift anisotropies. MD simulations indicate that this order is induced by the cationic proton-selective histidine at low pH. Furthermore, the water network has fewer hydrogen-bonding bottlenecks in the open state than in the closed state. Thus, faster dynamics and higher orientational order of water molecules in the open channel establish the water network structure that is necessary for proton hopping.
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Hybrid Pyridine–Pyridone Foldamer Channels as M2‐Like Artificial Proton Channels
Abstract Currently, completely abiotic channel systems that concurrently reproduce the high selectivity and high permeation rate of natural protein channels are rare. Here, we provide one such biomimetic channel system, i.e., a novel family of helically folded hybrid amide foldamers that can serve as powerful artificial proton channels to mimic key transport features of the exceptionally selective Matrix‐2 (M2) proton channels. Possessing an angstrom‐scale tubular pore 3 Å in diameter, these low water permeability artificial channels transport protons at a rate 1.22 and 11 times as fast as gramicidin A and M2 channels, respectively, with exceptionally high selectivity factors of 167.6, 122.7, and 81.5 over Cl−, Na+, and K+ions. Based on the experimental and computational findings, we propose a novel proton transport mechanism where a proton may create a channel‐spanning water chain from two or more short water chains to facilitate its own transmembrane flux via the Grotthuss mechanism.
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- PAR ID:
- 10368519
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 61
- Issue:
- 28
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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