Structural Basis of Chemoreception

化学感受的结构基础

• 批准号: 8507076
• 负责人: GRANT J JENSEN
• 金额: $ 27.63万
• 依托单位: CALIFORNIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8507076
• 关键词: 3-Dimensional; Active Sites; Address; Antibiotics; Back; Bacteria; Bacterial Infections; Binding; Biological; Biological Process; Cell model; Cells; Chemoreceptors; Chemotaxis; Chronic; Classification; Collaborations; Diabetes Mellitus; Disease; Electron Microscope; Electrons; Emerging Technologies; Environment; Exhibits; Film; Freezing; Grant; Health; Image; Individual; Industry; Inflammation; Length; Life; Malignant Neoplasms; Maps; Methods; Modeling; Molecular; Monitor; Motor; Nature; Noise; Nutrient; Optics; Organism; Phosphorylation; Phosphotransferases; Play; Positioning Attribute; Process; Proteins; Relative (related person); Resolution; Role; Rotation; Sampling; Signal Transduction; Spectrometry; Structure; Swimming; System; Tomogram; Toxin; Work; X-Ray Crystallography; base; combat; density; detector; dimer; flexibility; human disease; image processing; improved; in vivo; inorganic phosphate; molecular dynamics; mutant; pathogen; prevent; public health relevance; receptor; reconstruction; research study; response

DESCRIPTION (provided by applicant): Bacteria are nearly ubiquitous, play vital roles in industry and the environment, and are important actors in both health and disease for humans and other organisms. They are also small, easily-manipulable model cells that can be used to study basic cell biological studies. Motile bacteria, including many important pathogens, constantly monitor their environment in order to swim towards nutrients and away from toxins, a process called chemotaxis. Attractants and repellents bind to chemoreceptors, which are typically found at the poles of cells grouped together in highly cooperative, ordered arrays. Activated chemoreceptor arrays phosphorylate a protein messenger which in turn binds to flagellar motors, governing the rate of motor reversals and, ultimately, whether the cell continues to move forward or changes direction. While powerful methods like X-ray crystallography and NMR spectrometry have revealed the structures of individual domains of certain chemoreceptors at near-atomic resolution, they have not revealed how the chemoreceptors are arranged inside living cells or the structural basis of array cooperativity. Instead, we have begun to address these issues with an emerging technology, electron cryotomography, which can produce 3-D reconstructions of intact bacterial cells at "macromolecular" (1-5 nm) resolution, which is sufficient to visualize individual receptor dimers. Briefly, bacterial cultures are plunge-frozen in thin films across EM grids and then imaged from a range of angles as the sample is tilted incrementally around one or two axes. 3-D reconstructions are then calculated from the images, and sub-regions with common features can be averaged to increase the signal-to-noise ratio. Following recent work in which we showed that bacterial chemoreceptor arrays are universally arranged in a conserved, 12-nm hexameric lattice of trimers-of-receptor-dimers, here we propose to extend that work in resolution and by imaging fully-activated and -deactivated states. This should reveal how the proteins are arranged within the array as well as the structural basis of activation and array cooperativity. This information will in turn help us understand how bacteria accomplish their roles in health and disease and perhaps suggest new antibiotic targets or strategies.

描述（由申请人提供）：细菌几乎无处不在，在工业和环境中起着至关重要的作用，并且是人类和其他生物的健康和疾病中的重要参与者。它们也是小型，易于操纵的模型细胞，可用于研究基本的细胞生物学研究。运动细菌（包括许多重要的病原体）不断监测其环境，以便游泳营养并远离毒素，这一过程称为趋化性。吸引剂和驱蚊剂与化学感受器结合，这些感受器通常在将高度合作的有序阵列分组在一起的细胞的电线杆上发现。激活的化学感受器阵列磷酸化蛋白质使者，进而与鞭毛电动机结合，管理运动逆转的速率，最终，该细胞是继续向前移动还是改变方向。虽然X射线晶体学和NMR光谱等强大的方法揭示了某些化学感受器的单个结构以近原子分辨率的结构，但它们尚未揭示如何在活细胞内或阵列合作的结构基础上排列化学感受器。取而代之的是，我们已经开始使用新兴技术，电子冷冻理学来解决这些问题，该技术可以在“大分子”（1-5 nm）分辨率下产生完整的细菌细胞的3-D重建，这足以可视化单个受体二聚体。简而言之，细菌培养物在跨em网格的薄膜中被暴跌，然后从各个角度成像，因为样品在一个或两个轴上逐渐倾斜。然后根据图像计算3-D重建，并可以将具有共同特征的子区域取平均值以增加信噪比。在最近的工作中，我们表明细菌化学感受器阵列被普遍布置在受感受器二聚体的三聚体的保守，12 nm的六聚体晶格中，我们在这里提出，通过将该工作扩展到分辨率上，并通过全面激活和折射的状态进行成像。这应该揭示蛋白质如何在阵列中排列以及激活和阵列合作的结构基础。这些信息反过来将有助于我们了解细菌如何在健康和疾病中发挥作用，并可能提出新的抗生素靶标或策略。