X-ray Crystal Structure and Transport Mechanism of a Na+/galactoside Symporter

智能MERIT活细胞膜产生电化学能量，为许多细胞功能提供关键机制。插入到细胞膜中的蛋白质就像电池一样，利用能量将分子移入或移出细胞，使其化学成分适合正常的细胞功能。在某些细菌中存在的一种称为蜜糖渗透酶(Melb)的膜蛋白，将钠离子与糖(蜜糖)分子的转运耦合到细胞内。事实上，它利用钠进入的有利能量在细胞内建立高糖浓度。Melb人类同源物在许多组织中广泛表达，并被发现具有重要的生理意义。有许多蛋白质的作用相似，但确切的机制尚不清楚。Melb的三维结构(在原子水平上)将构成对理解分子运输机制至关重要的突破。该项目旨在通过X射线结晶学获得Melb的高分辨率晶体结构，并鉴定蛋白质中负责选择Melibiose和Na+的特定氨基酸。这将通过产生突变蛋白质并用定量的生化和生物物理方法测试它们的功能来完成。这项研究的结果将为理解膜蛋白如何转换离子能量以将糖或其他营养物质转移到细胞内提供关键信息。BROADER IMPACTS他的项目将提供一个平台，通过招募和激励本科生追求基础科学职业，并通过帮助他们发展技术技能和对实验科学的热情，促进尖端研究和高等教育的整合。少数民族占TTU本科生的20%。将特别努力招收这些学生，并为他们提供研究机会。研究生教育和博士后培训对未来科学至关重要。这项研究还将为研究生提供丰富的培训和教育机会，获得在研究中取得成功所需的扎实知识和经验技能，并为博士后研究员继续他们的教育和实验设施成为富有成效的独立研究人员。研究成果将通过影响较大的科学论文、书籍章节、课程材料、特邀讲座以及在科学会议或跨学科会议上的陈述及时和广泛地传播，以惠及广大受众。预期的高分辨率结构将存放在开放获取的蛋白质数据库中，以供更广泛的应用。该项目由分子和细胞生物科学部的细胞过程簇和化学部的生命过程化学计划联合支持。

INTELLECTUAL MERITThe membranes of living cells develop electrochemical energy that provides a critical mechanism for numerous cell functions. Proteins inserted in the membrane act like batteries and use the energy to move molecules in or out of the cell, making the chemical composition appropriate for normal cell function. The membrane protein called melibiose permease (MelB), present in certain bacteria, couples the transport of a sodium ion with a sugar (melibiose) molecule into the cell. In fact, it uses the favorable energy for sodium entry to build a high sugar concentration in the cell. A MelB human homologue is widely expressed in many tissues and has been found to be physiologically important. There are many proteins that work similarly, yet the precise mechanisms are not understood. The three-dimensional structure of MelB (at the atomic level) will constitute a breakthrough essential for the understanding of the molecular mechanism of transport. This project aims to obtain the high-resolution crystal structure of MelB by X-ray crystallography and to identify the specific amino acids in the protein responsible for selecting melibiose and sodium ion. This will be done by generating mutant proteins and testing their function with quantitative biochemical and biophysical methods. The results from this research will add crucial information to the understanding of how a membrane protein converts ionic energy to move sugar or other nutrients into a cell.BROADER IMPACTSThis project will provide a platform to foster the integration of cutting-edge research and higher education by recruiting and motivating undergraduate students to pursue careers in basic science and by helping them develop technical skills and passion towards experimental science. Minorities constitute 20% of TTU undergraduate students. A particular effort will be made to recruit and provide research opportunities to these students. Graduate education and postdoctoral training are critical for science of tomorrow. This research will also offer rich training and educational opportunities to graduate students, to gain solid knowledge and experiential skills necessary for success in research, and for postdoctoral fellows to further their education and experimental armamentarium to become productive independent investigators. The outcome of the research will be disseminated timely and broadly through high-impact scientific papers, book chapters, course materials, invited lectures, and presentations at scientific meetings or interdisciplinary conferences to reach broad audiences. The expected high-resolution structure will be deposited in the open-access Protein Data Bank for broader application.This project is jointly supported by the Cellular Processes Cluster in the Division of Molecular and Cellular Biosciences and the Chemistry of Life Processes program in the Chemistry Division.