近期，国际顶级学术期刊美国科学院院报 ( Proceedings of the National Academy of Sciences, 简称PNAS) 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为通讯作者题为“Molecular dynamics of ion transport through the open conformation of a bacterial voltage-gated sodium channel”的论文(2013年3月 28号，PNAS), 报道了他们关于细菌离子通道的离子输运机理研究的最新进展。PNAS为美国科学院主办的高水平的学术期刊，是科学界影响力最高的综合性期刊之一，涵盖数学、物理、 化学、生物、等所有科学领域。
参考文献：” Molecular dynamics of ion transport through the open conformation of a bacterial voltage-gated sodium channel” http://www.pnas.org/content/early/2013/03/28/1214667110
Voltage-gated cation channels are proteins that produce electrical signals in neurons and other excitable cells to regulate muscle contraction, gene expression, and release of hormones and neurotransmitters among other functions. In response to a change in transmembrane electrical potential, the channels open pores through which ions move passively across the membrane. The large family of cation channels includes those selective for sodium, potassium, or calcium. The opening and closing of these ion-specific channels is carefully choreographed to produce the electrical signals required by the nervous system for rapid signal transduction. Voltage-gated sodium channels have been causally linked with a wide range of neurological and cardiovascular diseases and hence are important pharmaceutical drug-development targets.
The crystal structure of the open conformation of a bacterial voltage-gated sodium channel pore from Magnetococcus sp. (NaVMs) has provided the basis for a molecular dynamics study defining the channel’s full ion translocation pathway and conductance process, selectivity, electrophysiological characteristics, and ion-binding sites. Microsecond molecular dynamics simulations permitted a complete time-course characterization of the protein in a membrane system, capturing the plethora of conductance events and revealing a complex mixture of single and multiion phenomena with decoupled rapid bidirectional water transport. The simulations suggest specific localization sites for the sodium ions, which correspond with experimentally determined electron density found in the selectivity filter of the crystal structure. These studies have also allowed us to identify the ion conductance mechanism and its relation to water movement for the NavMs channel pore and to make realistic predictions of its conductance properties. The calculated single-channel conductance and selectivity ratio correspond closely with the electrophysiology measurements of the NavMs channel expressed in HEK 293 cells. The ion translocation process seen in this voltage-gated sodium channel is clearly different from that exhibited by members of the closely related family of voltage-gated potassium channels and also differs considerably from existing proposals for the conductance process in sodium channels. These studies simulate sodiumchannel conductance based on an experimentally determined structure of a sodium channel pore that has a completely open transmembrane pathway and activation gate.