Characterisation of disulfide bond formation in bacterial pathogens: Unravelling the adaptation of a classical pathway into a virulence aid.

细菌是一种迷人的生物，能够适应各种环境条件。然而，由于这一特点，细菌病原体能够迅速进化以绕过人类的抗菌措施。抗生素耐药性的迅速增加，加上过去几十年来新抗生素研发的速度放缓至涓涓细流，可能很快导致一场公共卫生危机。抗生素耐药性发展的一个主要原因是，目前的抗生素靶向细菌细胞的组成部分（通常是蛋白质），这是微生物生存所必需的。这就产生了选择性压力，使得对抗生素有抗药性的细菌得以生存。避免“超级细菌”出现的一种方法是，通过开发针对致病菌武器（即允许细菌入侵并破坏宿主的分子）的化合物，试图使致病菌无害。在这种情况下，我有兴趣研究使用中央细菌途径的选择，这涉及到这些武器的组装，对抗细菌病原体。在细菌中，二硫键（DSB）蛋白质系统负责在位于主要细胞室外的蛋白质中形成额外的键（称为二硫键），需要承受恶劣的环境。由于大多数促进细菌毒力的分子都是基于蛋白质的，并且也位于细胞的外表面附近，因此它们依赖于DSB蛋白系统进行正确的组装。因此，通过研究致病菌的DSB蛋白，我们最终将能够利用这些知识开发新的、有效的方法来中和细菌致病生物体，而不会促进抗生素耐药性。我的假设是，在细菌病原体中，与无害的生物体相比，DSB途径已经多样化。这使得致病菌能够优化它们的工具包来入侵宿主并逃避宿主的防御机制。我的研究项目由三个部分组成，都与这个假设有关。在第一部分中，我的目标是使用生物信息学来确定病原体中DSB途径的所有变化，并确定致病菌DSB蛋白系统之间的潜在共同特征。这是开发对抗细菌毒力的新方法的第一步。在我的研究项目的第二部分，我将研究脑膜炎病原体脑膜炎奈瑟菌中DSB系统的关键组成部分（一种称为DsbA的蛋白质，它对几种细菌武器的组装至关重要）。在这种细菌中有三个DsbA拷贝，它们的功能尚不清楚。通过阐明它们在脑膜炎奈瑟菌发病机制中的作用，我们可以在未来找到更多的方法来对抗这种病原体。我的研究项目的第三部分也是最后一部分将集中在极具抗生素耐药性的细菌铜绿假单胞菌上，这种细菌会给术后和免疫功能低下的患者带来严重的问题。我计划研究在这种生物体中发现的DsbD蛋白的两个拷贝，它们被认为有助于其毒力，并有助于设计可用于疫苗开发的减毒菌株。我提出的研究旨在获得关于中心蛋白系统在细菌病原体中的作用的基本知识。这一知识对于开发急需的新抗菌策略至关重要，这将防止未来出现抗生素耐药性。

Bacteria are fascinating organisms that are able to adapt to a variety of environmental conditions. However, because of this characteristic, bacterial pathogens are able to quickly evolve to bypass human antibacterial measures. The rapid increase in resistance to antibiotics, combined with the slowing to a trickle of new antibiotics progressing through the pipeline over the past decades, could soon lead to a public health crisis.A major reason for antibiotic resistance development is the fact that current antibiotics target components of the bacterial cell (usually proteins) which are essential for the viability of the microorganism. This creates selective pressure for the survival of bacteria that are resistant to the antibiotic in use. A way to avoid the emergence of 'superbugs' is to try to render pathogenic bacteria harmless by developing compounds that target their weaponry i.e. the molecules that allow bacteria to invade and damage their host. In this context, I am interested in investigating the option of using a central bacterial pathway, which is involved in the assembly of these weapons, against bacterial pathogens.In bacteria, the Disulfide bond (DSB) protein system is responsible for the formation of additional linkages (called disulfide bonds) in proteins which are located outside the main cellular compartment and need to withstand harsh environments. Since the majority of molecules that promote bacterial virulence are protein-based and are also located near the outer surface of the cell, they are dependent on the DSB protein system for correct assembly. Therefore, by studying the DSB proteins of pathogenic bacteria we will eventually be able to use this knowledge for developing new, efficient ways of neutralising bacterial disease-causing organisms without promoting antibiotic resistance.My hypothesis is that in bacterial pathogens the DSB pathway has diversified, compared to organisms that are harmless. This allows pathogenic bacteria to optimise their toolkit for invading the host and evading the host's defence mechanisms. My research project consists of three parts all related to this hypothesis. In the first part, I aim to use bioinformatics to determine all variations of the DSB pathway in pathogens and to identify underlying common traits between DSB protein systems of pathogenic bacteria. This is the first step towards developing novel approaches against bacterial virulence. In the second part of my research project, I will study a pivotal component of the DSB system (a protein called DsbA, which is essential for the assembly of several bacterial weapons) in the human pathogen Neisseria meningitidis, the causative agent of meningitis. In this bacterium there are three copies of DsbA and their function remains unclear. By elucidating their involvement in the pathogenesis of N. meningitidis we can find additional ways to combat this pathogen in the future. The third and final part of my research project will focus on the extremely antibiotic-resistant bacterium Pseudomonas aeruginosa which causes severe problems in post-operational and immunocompromised patients. I plan to study the two copies of the protein DsbD, which are found in this organism and are thought to contribute to its virulence with the scope of contributing to the design of attenuated bacterial strains that could be used for vaccine development.My proposed research aims to acquire fundamental knowledge about the role of a central protein system in bacterial pathogens. This knowledge is key for the development of much-needed new antibacterial strategies which will prevent the emergence of antibiotic resistance in the future.