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J Phys Chem B. 2017 Aug 24;121(33):7899-7906. doi: 10.1021/acs.jpcb.7b05568. Epub 2017 Aug 9.

Nanoscale Ion Pump Derived from a Biological Water Channel.

Author information

1
Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801, United States.

Abstract

Biological molecular machines perform the work of supporting life at the smallest of scales, including the work of shuttling ions across cell boundaries and against chemical gradients. Systems of artificial channels at the nanoscale can likewise control ionic concentration by way of ionic current rectification, species selectivity, and voltage gating mechanisms. Here, we theoretically show that a voltage-gated, ion species-selective, and rectifying ion channel can be built using the components of a biological water channel aquaporin. Through all-atom molecular dynamics simulations, we show that the ionic conductance of a truncated aquaporin channel nonlinearly increases with the bias magnitude, depends on the channel's orientation, and is highly cation specific but only for one polarity of the transmembrane bias. Further, we show that such an unusually complex response of the channel to transmembrane bias arises from mechanical motion of a positively charged gate that blocks cation transport. By combining two truncated aquaporins, we demonstrate a molecular system that pumps ions against their chemical gradients when subject to an alternating transmembrane bias. Our work sets the stage for future biomimicry efforts directed toward reproducing the function of biological ion pumps using synthetic components.

PMID:
28745057
PMCID:
PMC5570624
DOI:
10.1021/acs.jpcb.7b05568
[Indexed for MEDLINE]
Free PMC Article

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