Structure, Dynamics and Activity of the Bacterial Secretosome

细菌分泌体的结构、动力学和活性

• 批准号: BB/Y004981/1
• 负责人: Ian Collinson
• 金额: $ 72.51万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FY004981%2F1
• 关键词: Structure; Dynamics; Activity; Bacterial; Secretosome

All cells are surrounded by membranes, made up from a double layer of fatty molecules called phospholipids. Cell membranes act as a molecular "skin", keeping the cell's insides in, and separating different biochemical reactions. This barrier needs to be traversed in a controlled manner to allow the import of nutrients, and removal of waste products, and for communication with the outside world. This is achieved by a wide range of proteins that reside in the various membranes. We understand a great deal about the diverse biological functions that membrane proteins bestow, such as transport, respiration, photosynthesis. However, we know very little about how membranes are formed, or about the necessary transport of proteins across or into membranes during their biogenesis.Our proposal aims to gain a complete understanding about how proteins are exported-protein secretion. The secretory ('Sec' for short) machinery is essential for life-for every cell in every organism. The project concerns this process, in bacterial cells. Bacteria secrete proteins for a wide range of membrane and extracellular activities including for: cell adherence, pathogenicity, the degradation of antibiotics, including also the biogenesis of the protective cell wall or envelope. A major class of bacteria known as Gram-negatives, possess a cell wall composed of a periplasm with a peptidoglycan (PG) layer, surrounded by an outer-membrane. The biogenesis of the cell wall is dependent on protein secretion from the cell interior through the Sec machinery. Proteins of the periplasm can readily fold and remain there, while those destined for the cell surface are delivered to another transport machine called the BAM complex, for incorporation into the outer-membrane. The journey from the inner- to the outer-membrane through the envelope, is poorly understood. We are concerned with the question: how do proteins make their way rapidly and efficiently through this very crowded and challenging environment? We have discovered that the protein transport machineries of the inner- (Sec) and outer-membranes (BAM) as well as various accessory factors concerned with quality control interact to form an assembly that spans the bacterial envelope, which we have called the bacterial secretosome. The existence of a contiguous conduit through the envelope will have far reaching implications for our understanding of outer-membrane biogenesis, including an answer to the question posed above.The project will harness complementary expertise in biochemistry and new breakthrough technologies for high resolution imaging (electron microscopy) and accurate mass measurements (mass spectrometry). This powerful combination will allow us to examine the activity, structure and dynamics of the assembly in order to understand how it works-how proteins are delivered through the inner-membrane to the periplasm and the outer-membrane. This knowledge is important because it will enlighten our understanding of a fundamental aspect of bacterial physiology, and inter-membrane transport throughout biology. Moreover, new advances in our understanding of the bacterial secretosome will help develop strategies to compromise envelope biogenesis and its regenerative capabilities-essential for survival. This would generate much needed ammunition in our fight against antimicrobial resistance (AMR).

所有细胞都被膜包围，由称为磷脂的双层脂肪分子组成。细胞膜充当分子“皮肤”，使细胞的内部内部保持并分离不同的生化反应。该障碍需要以受控的方式穿越，以允许进口营养，清除废物，并与外界进行沟通。这是通过存在于各种膜中的多种蛋白质来实现的。我们对膜蛋白赋予的多种生物学功能（例如运输，呼吸，光合作用）的多种生物学功能了解很多。但是，我们对膜的形成是如何形成的，或者在其生物发生过程中对蛋白质跨膜的必要运输。我们的建议旨在完全了解蛋白质如何出口蛋白质。分泌物（简称为“ SEC”）机械对于每个生物体中的每个细胞都至关重要。该项目涉及细菌细胞中的这一过程。细菌分泌多种膜和细胞外活性的蛋白质，包括：细胞依从性，致病性，抗生素降解，包括保护性细胞壁或包膜的生物发生。一类称为革兰氏阴性菌的细菌具有由肽聚糖（PG）层组成的细胞壁，被外膜包围。细胞壁的生物发生取决于细胞内部通过SEC机械的蛋白质分泌。周质的蛋白质可以容易地折叠并留在那里，而注定针对细胞表面的蛋白质则将其输送到另一台称为BAM复合物的运输机，以掺入外膜中。从信封中从内部到外膜的旅程知之甚少。我们关注一个问题：蛋白质如何通过这个非常拥挤和具有挑战性的环境快速有效地进行迅速有效的方式？我们已经发现，内部（SEC）和外膜（BAM）的蛋白质传输机器以及与质量控制相关的各种配件因素相互作用，形成跨越细菌包膜的组装，我们称之为细菌秘密体。通过信封的连续导管的存在将对我们对外膜生物发生的理解产生很大的影响，包括对上述问题的答案。该项目将利用生物化学方面的互补专业知识和高分辨率的新突破性技术（电子图像）显微镜）和准确的质量测量（质谱法）。这种强大的组合将使我们能够检查组件的活性，结构和动力学，以了解其工作原理，而蛋白质是通过内膜传递到Periplasm和外部膜的。这些知识很重要，因为它将启发我们对细菌生理学的基本方面以及整个生物学的膜间运输的理解。此外，我们对细菌分泌体的理解的新进展将有助于制定损害包膜生物发生及其再生能力 - 必不可少的生存能力。这将在我们反对抗菌抗性（AMR）的战斗中产生急需的弹药。