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Multiple pore lining residues modulate water permeability of GlpF
Kristyna Pluhackova1, Valentin Schittny2, Paul-Christian Bürkner1
1Stuttgart Center for Simulation Science, Cluster of Excellence EXC 2075, University of Stuttgart, Stuttgart, Germany.
Protein Science : a Publication of the Protein Society
|September 29, 2022
Summary
Researchers found that altering specific residues in aquaporins (AQPs) can control water flow. This discovery opens new avenues for tuning water permeability in AQPs for biotechnological uses.
Area of Science:
- Biophysics
- Molecular Biology
- Membrane Transport
Background:
- Aquaporins (AQPs) facilitate water transport across cell membranes.
- Despite conserved pore structures, AQP water permeability varies significantly.
- Mechanisms for regulating AQP water flux beyond direct gating are not fully understood.
Purpose of the Study:
- To experimentally confirm if flexible side chains of pore-lining residues can modulate AQP water permeability.
- To investigate the role of the conserved Arg residue in the selectivity filter of GlpF.
- To explore novel mechanisms for regulating aquaporin water transport.
Main Methods:
- Site-directed mutagenesis of the aquaglyceroporin GlpF in Escherichia coli.
- In silico molecular dynamics (MD) simulations.
- In vitro reconstitution and measurement of unitary water permeability in purified GlpF.
Main Results:
- Mutations outside the selectivity filter modulated the position of the conserved Arg residue.
- This modulation enhanced or reduced GlpF unitary water permeability, confirmed by MD simulations and in vitro experiments.
- Long-term MD simulations revealed that multiple pore-lining residues, not just the conserved Arg, influence water passage.
Conclusions:
- Aquaporin water permeability can be regulated by modulating the position and dynamics of pore-lining residues.
- Lipid bilayer asymmetry and transmembrane potential may influence AQP water permeability.
- These findings provide a new perspective on AQP regulation and potential for biotechnological applications.
Keywords:
GlpFaquaporindeterminants of water permeabilitygatingpore lining residuesprotein engineeringwater permeability modulationMore Related Videos
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