Mechanisms of spore engulfment in C. difficile

艰难梭状芽孢杆菌，俗称C.diff，是一种可以导致腹泻的细菌，通常会反复发作，在更严重的情况下，还会导致死亡。它对最常用的抗生素具有耐药性，使用这些药物为感染的发生创造了条件，因为肠道中正常的促进健康的细菌受到破坏。持续使用抗菌剂导致了新的耐药和多重耐药菌株，包括对几种常用抗生素的耐药性。在当前的大流行期间，世界各地大量使用抗生素使这种风险更高，寻找更具物种特异性的药物变得更加重要。C.diff的生命周期包括生长、形成称为孢子的休眠细胞，以及在条件有利的情况下孢子萌发。孢子为C.diff提供了强大的能力，使其能够留在环境和宿主中，对辐射、热和最常用的清洁剂具有抵抗力。由于这些特性，孢子负责传播C.diff感染(CDI)和重复发作。由抗生素耐药/多重耐药菌株产生的高度耐药孢子可能是我们在控制C.diff方面面临的最严重的挑战之一。尽管它很重要，但对孢子形成的确切机制的研究仍然很少。在这个项目中，我们建议结合我们的专业知识来研究孢子形成的一个关键方面。由于孢子是休眠细胞，产生抗菌素耐药性的可能性降低，这使这成为减少和控制CDI的一种创新方法，有待于未来探索。孢子的形成始于细菌细胞分裂成较小的细胞--前孔--和较大的母细胞。在被称为吞噬的过程中，前孔被母细胞包围。我们以前已经证明了两个关键的蛋白质机制-DP和Q：AH-在这个过程中是必不可少的，并开始揭示它们的一些关键特征。在这个项目中，我们将在这项工作的基础上回答三个关键问题：1.吞噬机制是如何组织的？我们将描述这些蛋白质之间的相互作用，它们的作用和它们的组织。我们还将确定这些蛋白质的结构，以更好地了解它们的作用模式。2.是什么力量推动了这一过程？我们将通过表征主要细胞被膜--肽聚糖--的组成，以及参与这一过程的任何其他蛋白质，来研究是什么驱动了吞噬。吞噬和孢子形成是如何影响疾病的？我们将使用疾病、传播和感染模型来研究这些机制在疾病中的作用。这个项目将增进我们对CDI基本过程的了解，并开辟控制感染的新的治疗途径。

Clostridioides difficile, commonly known as C. diff, is a bacterium that can cause diarrhoea, often with repeat episodes, and, in more severe cases, death. It is resistant to most commonly used antibiotics and using these drugs creates the conditions for infection to occur, as the normal, health-promoting bacteria in the gut is disrupted. Continued use of antimicrobials leads to new resistant and multi-resistant strains including against several commonly used antibiotics. Intense antibiotic use across the world during the current pandemic has made this risk higher and the search for more species-specific drugs even more important.The life cycle of C. diff involves growth, formation of dormant cells called spores, and germination of the spores when the conditions are favourable. Spores provide C. diff with a formidable capacity to remain in the environment and in the host, offering resistance to radiation, heat and most commonly used cleaning agents. Due to these properties, spores are responsible for transmission of C. diff infections (CDI) and repeat episodes. Highly resistant spores produced by antibiotic-resistant/multi-resistant strains may be one of the most serious challenges we face in terms of control of C. diff. Despite its importance, the exact mechanisms of spore formation are still poorly studied.In this project we propose to combine our expertise to study a key aspect of spore formation. As spores are dormant cells, the potential for antimicrobial resistance to arise is diminished, making this an innovative way to reduce and control CDI to be explored in the future. Spore formation starts with the bacterial cell dividing into a smaller cell - the forespore - and a bigger, mother cell. The forespore is then surrounded by the mother cell in a process called engulfment. We have previously shown that two key protein machineries - the DP and Q:AH - are essential for this process and started revealing some of their key features. In this project we will build upon this work and answer three key questions:1. How is the engulfment machinery organised?We will characterise the interactions between these proteins, their role and their organisation. We will also determine the structures of these proteins to better understand their mode of action. 2. Which forces drive the process?We will investigate what drives engulfment by characterising the composition of the main cell envelope - the peptidoglycan - how it varies and any other proteins involved in the process.3. How does engulfment and sporulation impact disease?We will investigate the role of these machineries in disease using disease, transmission and infection models.This project will enhance our knowledge of a fundamental process in CDI and open new therapeutic avenues to control infection.