Computational Studies of Sodium Symporters

钠同向转运蛋白的计算研究

• 批准号: 8539023
• 负责人: Michael Grabe
• 金额: $ 3.81万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 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 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8539023
• 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; DNA Sequence Rearrangement; 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; Simulate; 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）：细胞严格调节分子跨膜时空运动的能力对其存活至关重要。这种移动必须以选择性的方式进行，以确保细胞质和其他内部隔室的化学不受干扰。为了完成这些任务，细胞膜上布满了转运蛋白和通道，这些转运蛋白和通道通常对特定的细胞类型或细胞器具有特异性。目前建议的主要目标是使用计算方法来检查糖转运蛋白vSGLT的构象变化和功能操作。vSGLT是负责在人的小肠和肾脏中吸收单糖的转运蛋白的溶质钠同向转运蛋白家族的细菌成员。vSGLT与称为五螺旋反向重复（5 HIR）超家族的非常大的转运蛋白超家族相关。对它们的分子工作机制的进一步了解有可能帮助治疗与2型糖尿病（T2 DM）相关的疾病状态和严重脱水的治疗。在目标1中，我们将研究Na+和糖释放到细胞中的耦合。我们假设Na+的退出允许阻塞残基移动，并允许糖逃逸，就像用钥匙打开门一样。5 HIR超家族成员的所有结构都表现出这些门，因此阐明这一步骤可以为其他协同转运蛋白提供广泛的信息。Grabe实验室的计算将得到Abramson和Wright实验室突变vSGLT的转运试验的帮助。我们在目标2中的目标是使用计算药物发现来设计vSGLT和hSGLT 2的有效抑制剂。hSGLT 2是治疗T2 DM的药物靶点，因此我们的努力，加上Wright实验室的筛选，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的未知外向结构提供新的工具。在目标3中，我们将使用过渡路径采样结合GPU加速动力学来生成面向外和面向内构象之间的路径集合。这些模拟将揭示，在分子的细节，机械擒纵，使5 HIR超家族移动基板的Na+梯度的存在下。这些研究将由Abramson实验室的实验SAXS/WAXS和DEER测量指导。最后，hSGLT 1通过使用口服补液疗法在治疗严重脱水方面发挥着核心作用，据估计，自其问世以来，每年可挽救1-3百万人的生命。治疗+包括摄入葡萄糖/NaCl溶液。葡萄糖和Na在肠中被hSGLT 1吸收穿过刷状缘膜，随后沉积在血液中。每运输一摩尔葡萄糖伴随着4-6升水。我们将确定vSGLT如何以及在何种状态下允许水渗透，我们将探索不同糖对水渗透的影响。这最后一组计算可能会提出改进的解决方案，以帮助严重脱水患者的补液。1