Engineered Channel Asymmetry Extends Hydrogen-Bonding Networks for Proton Conduction.

Area of Science:

• Biophysics
• Protein Engineering
• Membrane Transport

Background:

• Proton transport is vital for biological energy processes but difficult to study in natural systems.
• Understanding proton conduction requires isolating key factors influencing selectivity and rate.
• Designed minimalist channels allow precise testing of transport mechanisms.

Purpose of the Study:

• To engineer novel proton channels and investigate how hydrogen-bonding network dynamics affect proton conductivity.
• To determine the primary determinants of efficient proton transport in engineered channels.
• To establish design principles for creating selective proton-conductive pathways.

Main Methods:

• Engineering of new-to-nature proton channels with varying vestibule polarity.
• Systematic substitution of amino acids (Ile-to-Ser) to modulate sidechain dynamics and pore hydration.
• Analysis of how sidechain arrangement and dynamics influence hydrogen-bonding networks and proton conduction rates.

Main Results:

• Proton conduction rates are primarily determined by asymmetric sidechain dynamics, not pore polarity or hydration.
• The position of polar residues (Ser) relative to other residues (Gln) significantly impacts channel hydration and dynamics.
• Asymmetry in the hydrogen-bonding network is crucial for extending pathways necessary for rapid proton translocation.

Conclusions:

• Proton transport efficiency is governed by the dynamic and asymmetric organization of hydrogen-bonding networks.
• Asymmetric sidechain dynamics represent a critical, tunable parameter for designing efficient proton-selective systems.
• This study provides fundamental insights and design principles for engineering artificial proton channels.