Principles of Surface Layer Biogenesis in Caulobacter crescentus

非专家概述原核生物是一组由细菌和古菌组成的单细胞生物体，形成一个由多层组成的细胞膜，具有不同的生物学功能。许多细菌和经过充分研究的古生菌的最外层由表层(或称S层)组成，这是一种包裹整个细胞的基于蛋白质的壁。S层的胞外蛋白形成了一个细胞结合的2D晶格，并以如此高的数量产生，被认为是世界上最丰富的蛋白质家族。S层与细胞发育、压力耐受性、耐药性和感染有关。使用尖端的冷冻电子显微镜技术，我们打算建立一个微观图像，展示这些蛋白质致密层是如何在微观水平上跨多种物种合成的，从而提高我们对原核膜是如何形成和维持的理解。耐药相关领域：S蛋鸡由艰难梭菌、炭疽芽孢杆菌、胎儿弯曲杆菌等多种致病菌组成。S层已被证明通过限制细菌进入细胞直接增加细菌对抗生素的耐药性，或间接通过促进破坏抗生素疗效的耐压生物膜的形成来增加细菌对抗生素的耐药性。了解S层的合成方法可以揭示旨在抑制它们对生物被膜形成和耐药性的贡献的治疗的潜在靶点。合成生物学：该项目将利用新月弯杆菌(以及其他潜在的细菌和古生菌物种)的菌株来表达S-允许用一系列材料标记的层。此外，新月藻S层由于S层固有的稳定性、自繁殖和活细胞中的高拷贝数，长期以来一直被认为是蛋白质生产、蛋白质分析和形成2D生物材料的平台。建立我们对S层是如何分泌和形成的知识，将为利用这些细胞进行合成生物学方法提供有用的信息。

Non-specialist Summary Prokaryotes, a group of single-celled organisms comprised of bacteria and archaea, form a cell envelope composed of multiple layers that serve variable biological functions. The outermost layer of many bacteria and well-studied archaea consists of a surface layer (or S-layer), a protein-based wall that encapsulates the entire cell. The extracellular proteins of the S-layer form a cell-bound 2D lattice, and are produced at such high numbers they are thought to be the most abundant family of protein in the world. The S-layer has been implicated in cell development, stress tolerance, drug resistance, and infection. Using cutting-edge cryo-electron microscopy techniques, we intend to build a microscopic image of how these protein-dense layers are synthesised on a microscopic level across multiple species, improving our understanding of how prokaryotic membranes are formed and maintained. Relevant BBSRC Priority Areas Combatting antimicrobial resistance: S-layers are formed by many pathogenic bacteria, such as Clostridium difficile, Bacillus anthracis, and Campylobacter fetus. S-layers have been shown to increase bacterial resistance to antimicrobials either directly by limiting their passage into the cell, or indirectly by promoting the formation of stress-tolerant biofilms which aberrate antibiotic efficacy. Understanding the methods by which S-layers are synthesised could reveal potential targets for therapies aimed at inhibiting their contribution to biofilm formation and drug resistance. Synthetic biology: This project will utilise strains of Caulobacter crescentus (along with other potential bacterial and archaeal species) engineered to express S-layers permissive to labelling with a range of materials. Additionally, the C. crescentus S-layer has long been attractive as a platform for protein production, protein analysis, and formation of 2D biomaterials, aided by the S-layers inherent stability, self-propagation, and high copy number in living cells. Building our knowledge of how the S-layer is secreted and formed will provide useful information when utilising these cells for synthetic biology approaches.