@article {268,
	title = {Nanoscale Ion Pump Derived from a Biological Water Channel},
	journal = {The Journal of Physical Chemistry B },
	volume = {121},
	year = {2017},
	month = {08/2017},
	pages = {7899{\textendash}7906 },
	abstract = {<p>Biological molecular machines perform the\&nbsp;work of supporting life at the smallest of scales, including\&nbsp;the work of shuttling ions across cell boundaries and against\&nbsp;chemical gradients. Systems of artifi cial channels at the\&nbsp;nanoscale can likewise control ionic concentration by way of\&nbsp;ionic current rectifi cation, species selectivity, and voltage\&nbsp;gating mechanisms. Here, we theoretically show that a voltagegated,\&nbsp;ion species-selective, and rectifying ion channel can be\&nbsp;built using the components of a biological water channel\&nbsp;aquaporin. Through all-atom molecular dynamics simulations,\&nbsp;we show that the ionic conductance of a truncated aquaporin\&nbsp;channel nonlinearly increases with the bias magnitude, depends on the channel{\textquoteright} s orientation, and is highly cation specific but only\&nbsp;for one polarity of the transmembrane bias. Further, we show that such an unusually complex response of the channel to\&nbsp;transmembrane bias arises from mechanical motion of a positively charged gate that blocks cation transport. By combining two\&nbsp;truncated aquaporins, we demonstrate a molecular system that pumps ions against their chemical gradients when subject to an\&nbsp;alternating transmembrane bias. Our work sets the stage for future biomimicry eff orts directed toward reproducing the function\&nbsp;of biological ion pumps using synthetic components.</p>
},
	doi = {10.1021/acs.jpcb.7b05568},
	author = {Karl Decker and Martin Page and Aleksei Aksimentiev}
}
