Computational Studies of Sodium Symporters

钠同向转运蛋白的计算研究

• 批准号: 8917970
• 负责人: Michael Grabe
• 金额: $ 22.58万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-30 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8917970
• 关键词: Adopted; Adsorption; Affinity; Amino Acid Neurotransmitters; Architecture; Binding; Binding Sites; Biological Assay; Biological Process; Blood; Cells; Chemistry; Computing Methodologies; Coupled; Coupling; Crystallization; Cytoplasm; Data; Dehydration; Deposition; Diabetes Mellitus; Disease; Docking; Drug Design; Drug Targeting; Energy Metabolism; Engineering; Ensure; Environment; Event; Exhibits; Extracellular Space; Failure; Family; Free Energy; Galactose; Glucose; Goals; Homeostasis; Human; Ingestion; Intestines; Ions; Kidney; Lead; Ligands; Measurement; Mechanics; Mediating; Membrane; Mental Depression; Metabolism; Modeling; Mole the mammal; Molecular; Molecular Conformation; Movement; Mutation; Nature; Non-Insulin-Dependent Diabetes Mellitus; Oral Rehydration Therapy; Organelles; Patients; Play; Positioning Attribute; Proteins; Pump; Rehydrations; Resolution; Role; Sampling; Small Intestines; Sodium; Solutions; Structure; Testing; Thick; Thyroid Gland; Urea; Water; Work; blind; brush border membrane; cell type; computer studies; design; drug discovery; extracellular; improved; inhibitor/antagonist; member; mutant; operation; prevent; screening; simulation; solute; sugar; symporter; tool; uptake

DESCRIPTION (provided by applicant): The ability of the cell to tightly regulate the temporal and spatial movement of molecules across membranes is central to its survival. This movement has to be done in a selective manner to ensure that the chemistry of the cytoplasm and other internal compartments is not disturbed. To carry out these tasks, membranes are studded with transporters and channels that are often specific to particular cell types or organelles. The primary objective of the current proposal is to use computational methods to examine the conformational changes and functional operation of the sugar transporter vSGLT. vSGLT is the bacterial member of the solute sodium symporter family of transporters responsible for adsorption of simple sugars in the small intestine and kidneys of humans. vSGLT is related to a very large superfamily of transporters called the five helix inverted repeat (5HIR) superfamily. An increased understanding of their molecular workings has the potential to help in treating disease states related to type 2 diabetes mellitus (T2DM) and the treatment of severe dehydration. In Aim 1, we will study the coupling of Na+ and sugar release into the cell. We hypothesize that Na+ exit allows blocking residues to move out of the way and allow sugar to escape, much like opening a gate with a key. All structures of 5HIR superfamily members exhibit these gates, so elucidating this step could be widely informative to other cotransporters. Computations in the Grabe lab will be aided by transport assays on mutant vSGLTs in the Abramson and Wright labs. Our goal in Aim 2 is to use computational drug discovery to design potent inhibitors to vSGLT and hSGLT2. hSGLT2 is a drug target for treating T2DM, so our efforts, coupled with screening in the Wright lab, could lead to new therapies. High-affinity inhibitors to vSGLT would provide a new tool for stabilizing and crystallizing the unknown, outward-facing structure of vSGLT. In Aim 3, we will use transition path sampling coupled with GPU-accelerated dynamics to generate the ensemble of paths between the outward-facing and inward-facing conformations. These simulations will reveal, in molecular detail, the mechanical escapement that allows the 5HIR superfamily to move substrates in the presence of a Na+ gradient. These studies will be guided by experimental SAXS/WAXS and DEER measurements in the Abramson lab. Finally, hSGLT1 plays a central role in the treatment of severe dehydration through the use of Oral Rehydration Therapy, which is estimated to save 1-3 millions lives per year since its inception. Treatment + consists of ingestion of a glucose/NaCl solution. The glucose and Na are absorbed across the brush border membrane by hSGLT1 in the intestine and subsequently deposited in the blood. Each transported mole of glucose is accompanied by 4-6 L of water. We will determine how and in which state(s) vSGLT allows water to permeate, and we will explore the effect of different sugars on water permeation. This final set of computations may suggest improved solutions to aid in rehydration of severally dehydrated patients. 1

描述（由申请人提供）：细胞严格调节跨膜分子的时间和空间运动的能力是其生存的核心。必须以选择性的方式进行这种运动，以确保不会受到细胞质和其他内部隔室的化学性质。为了执行这些任务，膜上饰有通常针对特定细胞类型或细胞器的转运蛋白和通道。当前建议的主要目的是使用计算方法检查糖转运蛋白VSGLT的构象变化和功能操作。 VSGLT是溶质钠对孢子的细菌成员，这些转运蛋白家族负责在人类的小肠和肾脏中吸附较小糖。 VSGLT与一个非常大的转运蛋白超级家族有关，称为五螺旋倒重复（5HIR）超家族。对它们的分子起作用的越来越多的了解有可能帮助治疗与2型糖尿病（T2DM）和严重脱水的治疗相关的疾病状态。在AIM 1中，我们将研究Na+和糖释放到细胞中的耦合。我们假设NA+出口允许阻塞残留物移出并允许糖逸出，就像用钥匙打开大门一样。 5HIR超家族成员的所有结构都表现出这些大门，因此阐明此步骤可能对其他共转运蛋白提供广泛的信息。 Grabe Lab中的计算将通过在Abramson和Wright Labs中的突变体VSGLT上进行的运输测定来帮助。 AIM 2的目标是使用计算药物发现来设计有效的VSGLT和HSGLT2抑制剂。 HSGLT2是治疗T2DM的药物目标，因此我们的努力以及在Wright Lab中的筛查可能会导致新的疗法。 VSGLT的高亲和力抑制剂将为稳定和结晶VSGLT的未知，向外结构提供新的工具。在AIM 3中，我们将使用与GPU加速动力学相结合的过渡路径采样，以生成外向构象和向内构象之间的路径集合。这些模拟将揭示出分子详细的机械逃逸，该机械逸出使5HIR超家族在存在Na+梯度的情况下移动底物。这些研究将以艾布拉姆森实验室中的实验萨克斯/蜡和鹿的测量为指导。最后，HSGLT1通过使用口服补液疗法在严重脱水的治疗中起着核心作用，据估计，这是自成立以来每年每年挽救1-3千万的生命。治疗 +由摄入葡萄糖/NaCl溶液组成。葡萄糖和Na在肠中被HSGLT1吸收在刷子边界膜上，然后沉积在血液中。每个转运的葡萄糖摩尔都伴随着4-6 L的水。我们将确定如何以及在哪种状态下VSGLT允许水渗透，我们将探索不同糖对水渗透的影响。这组最终的计算可能提出了改进的解决方案，以帮助补液减少了分隔脱水的患者。 1