UNDERSTANDING THE MECHANICS OF ENERGY CONVERSION IN NA+-DEPENDENT CO-TRANSPORTE

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 利用5-螺旋反向重复基序的膜转运蛋白最近已成为最大的次级活性转运蛋白结构类别。这些膜蛋白在所有生命王国中都能找到，在哺乳动物中，它们存在于所有组织中，负责跨膜运输氨基酸和糖等小分子。他们使用电化学梯度来浓缩这些底物，使用最初在20世纪50年代和60年代概述的交替访问机制(1-3)。随着高分辨率结构的确定，这种机制在分子水平上的工作原理才刚刚开始被理解。在这里，我们打算使用分子动力学模拟来研究海洋细菌副溶血性弧菌的钠-半乳糖共转运蛋白(SGLT)中的这一过程，vSGLT的结构最近由我们的合作者Jeff Abramson博士(UCLA)和Ernie Wright博士(UCLA)(4)解决。我们拟议的工作将广泛地解决通过次级主动转运蛋白进行能量转导的基本生物学现象。具体地说，它将阐明糖的代谢和与SGLT相关的水运输，后者构成了口服补液疗法的基础，据估计，口服补液疗法已将因严重腹泻而导致的儿童死亡率从1980年的460万降至2000年的160万(5)。我们将通过两个具体目标开展这项工作： 具体目标1.vSGLT中钠和半乳糖偶联的特性。 具体目标2.水和尿素在vSGLT中的渗透。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Membrane transport proteins that utilize a 5-helix inverted repeat motif have recently emerged as the largest structural class of secondary active transporters. These membrane proteins are found throughout all kingdoms of life, and in mammals they are found in all tissues, where they are responsible for transporting small molecules such as amino acids and sugars across membranes. They use electrochemical gradients to concentrate these substrates using an alternating access mechanism originally outlined in the 1950s and 60s (1-3). How this mechanism works at the molecular level is only beginning to be understood as high-resolution structures are being determined. Here, we intend to use molecular dynamics simulations to investigate this process in the sodium-galactose co-transporter (SGLT) from the marine bacterium Vibrio parahaemolyticus, called vSGLT, whose structure was recently solved by our collaborators Drs. Jeff Abramson (UCLA) and Ernie Wright (UCLA) (4). Our proposed work will broadly address the basic biological phenomenon of energy transduction by secondary active transporters. Specifically, it will shed light on sugar metabolism and SGLT associated water transport, the later of which forms the basis of Oral Rehydration Therapy, which is estimated to have decreased childhood mortality due to severe diarrhea from 4.6 million in 1980 to 1.6 million in 2000 (5). We will carry out this work through two specific aims: Specific Aim 1. Characterization of sodium and galactose coupling in vSGLT. Specific Aim 2. Water and urea permeation through vSGLT.