Optimizing water permeability through the hourglass shape of aquaporins

Simon Gravelle (1) , Laurent Joly (1) , François Detcheverry (1) , Christophe Ybert (1) , Cécile Cottin-Bizonne (1) , Lydéric Bocquet (1, 2)

1 ILM - Institut Lumière Matière [Villeurbanne]
2 MSE 2 - Multiscale Material Science for Energy and Environment

The ubiquitous aquaporin channels are able to conduct water across cell membranes, combining the seemingly antagonist functions of a very high selectivity with a remarkable permeability. Whereas molecular details are obvious keys to perform these tasks, the overall efficiency of transport in such nanopores is also strongly limited by viscous dissipation arising at the connection between the nanoconstriction and the nearby bulk reservoirs. In this contribution, we focus on these so-called entrance effects and specifically examine whether the characteristic hourglass shape of aquaporins may arise from a geometrical optimum for such hydrodynamic dissipation. Using a combination of finite-element calculations and analytical modeling, we show that conical entrances with suitable opening angle can indeed provide a large increase of the overall channel permeability. Moreover, the optimal opening angles that maximize the permeability are found to compare well with the angles measured in a large variety of aquaporins. This suggests that the hourglass shape of aquaporins could be the result of a natural selection process toward optimal hydrodynamic transport. Finally, in a biomimetic perspective, these results provide guidelines to design artificial nanopores with optimal performances.

Mots clés: nanofluidics; hydrodynamic permeability; biochannels

Domaines: Matière Molle [cond-mat.soft]; Mécanique des fluides [physics.class-ph]; Mécanique des fluides [physics.class-ph]; Dynamique des Fluides [physics.flu-dyn]; Biophysique

Simon Gravelle, Laurent Joly, François Detcheverry, Christophe Ybert, Cécile Cottin-Bizonne, et al.. Optimizing water permeability through the hourglass shape of aquaporins. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110 (41), pp.16367-16372. ⟨10.1073/pnas.1306447110⟩. ⟨hal-00873654⟩