Capturing eukaryotic transporters in action

捕获行动中的真核转运蛋白

• 批准号: BB/V006487/1
• 负责人: Argyris Politis
• 金额: $ 52.04万
• 依托单位: King's College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FV006487%2F1
• 关键词: Capturing; eukaryotic; transporters; action

All cells are surrounded by a membrane made up of fatty lipid molecules. This membrane acts as an effective barrier separating the contents of the cell from the external environment. The lipid membrane itself is impermeable to all but a limited number of molecules, however cells need to have a means of taking up key nutrients and removing waste products. The import and export of a wide range of molecules across the membrane is mediated via a system of specialised proteins called membrane transporters, which are embedded into the lipid layer. These transporter proteins bind a specific substrate or cargo on one side of the membrane, undergo a reconfiguration and then release the substrate on the other side of the membrane. The ability to transport key nutrients into and out of cells is fundamental to cellular function. These inbuilt transport mechanisms also represent a potential means of direct drug delivery into cells. Substantial progress is being made in understanding the mechanism of action of individual membrane transporters in particular through structural studies, however these approaches fail to capture the full dynamic range of different protein conformations required for transport activity. Here we will use a novel technique, Hydrogen Deuterium eXchange-Mass Spectrometry (HDX-MS) which provides information on which regions of a protein are accessible to the external environment. These regions change as the protein changes conformations and this information can be captured as a change in the level of deuterium labelling. Thus, differences in the deuterium labelling of different forms of the protein can allow researchers to build up a picture of precisely how a protein changes its shape to performs its function. The application of HDX-MS to membrane proteins represents an emerging technology and this is particularly true with regard to membrane proteins from complex organisms. The protein we will use for these studies is a nucleobase transporter from a fungus, UapA, which is an important transporter in its own right but is also an excellent model for a large number of human and other mammalian transporters. Our groups have studied UapA for a number of years and have many tools including a range of different substrates, inhibitors and mutant forms that can be used to obtain information on the different conformations adopted by the protein. The lipid molecules that make up the membrane are known to have important effects on structure and function of many membrane proteins including UapA. We have previously identified a series of lipids important for UapA, however it is not known what effect these lipids have on the conformational state of the protein. We will use HDX-MS to interrogate the conformational mechanism of UapA in artificial lipid environments. Our research will provide a uniquely detailed picture of how UapA carries out its transport function and how this is affected by its surrounding environment. This information is also relevant to other closely related proteins and may facilitate drug discovery efforts targeting UapA and other membrane transporters.

所有细胞都被由脂肪脂质分子组成的膜包围。该膜充当将细胞内容物与外部环境分开的有效屏障。除了有限数量的分子外，脂质膜本身对所有分子都是不可渗透的，但是细胞需要有一种方法来吸收关键营养物质并清除废物。多种跨膜分子的输入和输出是通过一种称为膜转运蛋白的特殊蛋白质系统介导的，该蛋白质嵌入脂质层中。这些转运蛋白在膜的一侧结合特定的底物或货物，经历重新配置，然后在膜的另一侧释放底物。将关键营养物质输送进出细胞的能力是细胞功能的基础。这些内置的转运机制也代表了将药物直接输送到细胞中的潜在手段。在理解单个膜转运蛋白的作用机制方面正在取得实质性进展，特别是通过结构研究，但是这些方法未能捕获转运活性所需的不同蛋白质构象的完整动态范围。在这里，我们将使用一种新技术，即氢氘交换质谱 (HDX-MS)，它提供有关蛋白质的哪些区域可与外部环境接触的信息。这些区域随着蛋白质构象的变化而变化，并且该信息可以作为氘标记水平的变化来捕获。因此，不同形式的蛋白质的氘标记的差异可以让研究人员准确地了解蛋白质如何改变其形状以发挥其功能。 HDX-MS 在膜蛋白上的应用代表了一项新兴技术，对于来自复杂生物体的膜蛋白尤其如此。我们将用于这些研究的蛋白质是来自真菌的核碱基转运蛋白 UapA，它本身就是一种重要的转运蛋白，但也是大量人类和其他哺乳动物转运蛋白的优秀模型。我们的团队对 UapA 进行了多年的研究，并拥有许多工具，包括一系列不同的底物、抑制剂和突变体形式，可用于获取有关蛋白质采用的不同构象的信息。已知构成膜的脂质分子对包括 UapA 在内的许多膜蛋白的结构和功能具有重要影响。我们之前已经鉴定了一系列对 UapA 重要的脂质，但尚不清楚这些脂质对蛋白质的构象状态有什么影响。我们将使用 HDX-MS 来探讨人工脂质环境中 UapA 的构象机制。我们的研究将提供关于 UapA 如何执行其运输功能以及其如何受到周围环境影响的独特详细信息。该信息还与其他密切相关的蛋白质相关，并可能促进针对 UapA 和其他膜转运蛋白的药物发现工作。