Oriented chiral water wires in artificial transmembrane channels.

TitleOriented chiral water wires in artificial transmembrane channels.
Publication TypeJournal Article
Year of Publication2018
AuthorsKocsis I, Sorci M, Vanselous H, Murail S, Sanders SE, Licsandru E, Legrand Y-M, van der Lee A, Baaden M, Petersen PB, Belfort G, Barboiu M
JournalSci Adv
Volume4
Issue3
Paginationeaao5603
Date Published2018 03
ISSN2375-2548
Abstract

Aquaporins (AQPs) feature highly selective water transport through cell membranes, where the dipolar orientation of structured water wires spanning the AQP pore is of considerable importance for the selective translocation of water over ions. We recently discovered that water permeability through artificial water channels formed by stacked imidazole I-quartet superstructures increases when the channel water molecules are highly organized. Correlating water structure with molecular transport is essential for understanding the underlying mechanisms of (fast) water translocation and channel selectivity. Chirality adds another factor enabling unique dipolar oriented water structures. We show that water molecules exhibit a dipolar oriented wire structure within chiral I-quartet water channels both in the solid state and embedded in supported lipid bilayer membranes (SLBs). X-ray single-crystal structures show that crystallographic water wires exhibit dipolar orientation, which is unique for chiral I-quartets. The integration of I-quartets into SLBs was monitored with a quartz crystal microbalance with dissipation, quantizing the amount of channel water molecules. Nonlinear sum-frequency generation vibrational spectroscopy demonstrates the first experimental observation of dipolar oriented water structures within artificial water channels inserted in bilayer membranes. Confirmation of the ordered confined water is obtained via molecular simulations, which provide quantitative measures of hydrogen bond strength, connectivity, and the stability of their dipolar alignment in a membrane environment. Together, uncovering the interplay between the dipolar aligned water structure and water transport through the self-assembled I-quartets is critical to understanding the behavior of natural membrane channels and will accelerate the systematic discovery for developing artificial water channels for water desalting.

DOI10.1126/sciadv.aao5603
Alternate JournalSci Adv
Citation Key2018|2092
PubMed ID29582016
PubMed Central IDPMC5866074