Impact of the C. difficile small acid soluble proteins on spore physiology

艰难梭菌是医院内腹泻的主要原因， 长期的医疗保健服务。除了患者费用外， C.据估计，美国医疗保健系统的艰难感染费用为50亿美元。 虽然C.在美国，艰难梭菌感染正在上升，令人惊讶的是， 关于C.艰难梭菌孢子保持其极端的抗性特性。 C.艰难梭菌被认为以休眠孢子的形式被宿主获得， 污染了医院环境。在其他生物体中，大量的耐药性 紫外线和遗传毒性化学物质的主要来源是小酸溶性蛋白（SASPs）。SASP 被认为与DNA非特异性结合并改变其形式以防止 胸苷-胸苷加合物（胸苷二聚体）。这些蛋白质还提供 对活性氧、酸、交联剂的耐受性和较小的耐热性。In C. 然而，对于这些重要的蛋白质如何对C. 艰难梭菌孢子抗性谱。C.艰难梭菌SspA提供对UV的抗性，但SspA和SspB 在孢子形成中发挥作用。梭艰难梭菌ΔsspA ΔsspB双突变株不 产生成熟的孢子，这表明这些SASP在某种程度上调节孢子形成， 程序.本申请将从三个方面分析SASPs对孢子生物学的影响。目的 1研究了SspA和SspB对芽孢形成的作用以及C.艰难SASPs 保护C。紫外线损伤的艰难基因组。目标2研究了 SASP有助于孢子形成。目的3研究了蛋白酶如何降解 SASPs在萌发过程中受到调节，其活性谱在孢子中。成功 这些目标的完成将彻底描述SASP对孢子抗性的影响 并引导未来设计能够清洁污染环境的试剂。

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea in the hospital and long term health care settings. In addition to the patient toll, the treatment-associated costs of C. difficile infections to the United States healthcare system have been estimated at $5 billion. Although the rate of C. difficile infection in the United States is rising, surprisingly little is known about the mechanisms by which C. difficile spores maintain their extreme resistance properties. C. difficile is believed to be acquired by the host in the form of a dormant spore which contaminates the nosocomial environment. In other organisms, a significant amount of resistant to UV and genotoxic chemicals is provided by the small acid soluble proteins (SASPs). SASPs are thought to nonspecifically bind to DNA and alter its form to prevent the formation of thymidyl-thymidine adducts (thymidine dimers) upon UV exposure. These proteins also provide resistances to reactive oxygen, acids, crosslinking agents and minor resistance to heat. In C. difficile, however, nothing is known about how these important proteins contribute to the C. difficile spore resistance spectrum. C. difficile SspA provides resistance to UV but SspA & SspB play a role in spore formation. The C. difficile ΔsspA ΔsspB double mutant strain does not produce mature spores suggesting that these SASPs regulate, at some level, the sporulation program. This application will analyze the impact of SASPs on spore biology in three aims. Aim 1 investigates how SspA & SspB contributes to spore formation and how the C. difficile SASPs protect the C. difficile genome from UV damage. Aim 2 investigates mechanisms by which the SASPs contribute to spore formation. Aim 3 investigates how the protease that degrades the SASPs during germination is regulated and its spectrum of activity in the spore. Successful completion of these aims will thoroughly characterize the impact of SASPs on spore resistance and lead to the future design of agents that can clean a contaminated environment.