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离子通道分子输运机制

近期,国际顶级学术期刊自然杂志子刊Nature Communications发表了上海交大自然科学研究院及物理系特别研究员Jakob Ulmschneider及合作者题为“Mechanisms of molecular transport through the urea channel of Helicobacter pylori”的论文(2013年12月 05号,Nat. Comm.), 报道了他们关于幽门螺杆菌离子通道的分子输运机理研究的最新进展,幽门螺杆菌感染是胃炎、溃疡、和胃癌的主要致病因素。Nature Communications为科学界影响力最高的交叉科学综合性期刊之一,涵盖物理、 化学、生物、等科学领域。

参考文献:” Mechanisms of molecular transport through the urea channel of Helicobacter pylori” http://www.nature.com/ncomms/2013/131205/ncomms3900/full/ncomms3900.html

Helicobacter pylori survival in acidic environments relies on cytoplasmic hydrolysis of gastric urea into ammonia and carbon dioxide, which buffer the pathogen’s periplasm. Urea uptake is greatly enhanced and regulated by HpUreI, a proton-gated inner membrane channel protein essential for gastric survival of H. pylori. The crystal structure of HpUreI describes a static snapshot of the channel with two constriction sites near the center of the bilayer that are too narrow to allow passage of urea or even water. Here we describe the urea transport mechanism at atomic resolution, revealed by unrestrained microsecond equilibrium molecular dynamics simulations of the hexameric channel assembly. Two consecutive constrictions open to allow conduction of urea, which is guided through the channel by interplay between conserved residues that determine proton rejection and solute selectivity. Remarkably, HpUreI conducts water at rates equivalent to aquaporins, which might be essential for efficient transport of urea at small concentration gradients.