Molecular Mechanisms of Membrane Transport

膜运输的分子机制

• 批准号: 7924300
• 负责人: DAVID S CAFISO
• 金额: $ 22.9万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7924300
• 关键词: Action Potentials; Active Biological Transport; Address; Affinity; Antibiotics; Apoptosis; Bacteria; Binding; Boxing; Carrier Proteins; Cell membrane; Cholera; Citrates; Complex; Coupling; Crystallization; Development; Electron Spin Resonance Spectroscopy; Electrons; Environment; Equilibrium; Escherichia coli; Event; Family; Ferrichrome; Goals; Gram-Negative Bacteria; Growth; Ions; Iron Chelating Agents; Knowledge; Ligands; Lipids; Maintenance; Measurement; Membrane; Membrane Proteins; Membrane Transport Proteins; Meningitis; Metabolism; Modeling; Molecular; Molecular Models; N-terminal; Normal Cell; Nutrient; Pathogenicity; Pertussis; Physiological; Polyethylene Glycols; Process; Proteins; Relative (related person); Research; Resolution; Shapes; Signal Transduction; Site; Spin Labels; Structural Models; Structure; Surface; System; Testing; Thermodynamics; Trace Elements Nutrition; Transmembrane Transport; Transport Process; Vitamin B 12; Work; base; design; fascinate; hatching; insight; interest; molecular modeling; mutant; pathogen; periplasm; protein complex; protein folding; protein function; protein protein interaction; protein structure; public health relevance; solute; success; uptake

DESCRIPTION (provided by applicant): Active membrane transport is a critical process for normal cell metabolism, including the maintenance of ion-gradients, osmotic balance, action potentials and apoptosis. The proposed work will address key questions regarding the mechanisms of nutrient uptake in Escherichia coli and other Gram negative bacteria. In E. coli, rare nutrients are sequestered by specific outer- membrane proteins that derive energy by coupling to the inner-membrane protein TonB. These TonB-dependent transporters include BtuB, which is responsible for vitamin B12 transport, and FhuA, FecA and FepA, which are responsible for the transport of various forms of chelated iron. TonB-dependent transporters are abundant in Gram negative bacterial and are critical to the success of many bacterial pathogens, such as the bacteria that result in meningitis, cholera and pertussis. Because they are unique to bacteria, these transporters are a logical target for the development of new classes of antibiotics. High-resolution crystallographic models have been obtained for a number of TonB-dependent transporters; however, the mechanisms by which transport takes place is unclear. The proposed work will utilize site-directed spin labeling and EPR spectroscopy to test models for the molecular mechanisms of TonB-dependent transport, determine the mechanisms of transmembrane signaling and determine the mechanisms by which the transporter-TonB interaction is regulated. Finally, the structure and dynamics of these transporters (which are based upon 2-barrels) are influenced by both solute and lipid environment. Because of the critical need to generate and interpret high-resolution structural models of membrane proteins, the proposed work will also quantitate the influence of solutes and lipid environment on the structure of this class of membrane proteins. PUBLIC HEALTH RELEVANCE: The proposed research will determine the molecular mechanisms by which bacteria transport scarce nutrients across their cell membrane. This transport is critical to the survival of bacteria, and it is essential for the success of many bacterial pathogens, such as the bacteria that cause meningitis, cholera and pertussis. Knowledge of these transport mechanisms will assist with the development of new antibiotics that can inhibit bacterial growth.

描述（由申请人提供）：主动膜转运是正常细胞代谢的关键过程，包括维持离子梯度、渗透平衡、动作电位和细胞凋亡。拟议的工作将解决有关大肠杆菌和其他革兰氏阴性细菌营养吸收机制的关键问题。在大肠杆菌中，稀有营养物质被特定的外膜蛋白隔离，这些蛋白通过与内膜蛋白 TonB 偶联来获取能量。这些 TonB 依赖性转运蛋白包括负责维生素 B12 转运的 BtuB，以及负责转运各种形式的螯合铁的 FhuA、FecA 和 FepA。 TonB 依赖性转运蛋白在革兰氏阴性细菌中含量丰富，对于许多细菌病原体（例如导致脑膜炎、霍乱和百日咳的细菌）的成功至关重要。由于它们是细菌所独有的，因此这些转运蛋白是开发新型抗生素的合理目标。已经获得了许多依赖于 TonB 的转运蛋白的高分辨率晶体学模型；然而，运输发生的机制尚不清楚。拟议的工作将利用定点自旋标记和 EPR 光谱来测试 TonB 依赖性转运的分子机制模型，确定跨膜信号传导机制并确定转运蛋白-TonB 相互作用的调节机制。最后，这些转运蛋白（基于 2 桶）的结构和动力学受到溶质和脂质环境的影响。由于迫切需要生成和解释膜蛋白的高分辨率结构模型，因此拟议的工作还将量化溶质和脂质环境对此类膜蛋白结构的影响。公共健康相关性：拟议的研究将确定细菌跨细胞膜运输稀缺营养物质的分子机制。这种运输对于细菌的生存至关重要，对于许多细菌病原体的成功至关重要，例如引起脑膜炎、霍乱和百日咳的细菌。了解这些转运机制将有助于开发能够抑制细菌生长的新型抗生素。