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

艰难梭状芽胞杆菌是医院抗生素相关性腹泻的主要原因 长期保健环境。除了患者的费用外，与治疗相关的成本 据估计，美国医疗系统感染艰难梭菌的金额为50亿美元。 尽管艰难梭菌在美国的感染率正在上升，但令人惊讶的是，人们对此知之甚少 艰难梭菌孢子保持其极端抗药性的机制。 艰难梭菌被认为是由宿主以休眠孢子的形式获得的 污染了医院环境。在其他生物体中，大量的抗药性 对紫外线和遗传毒性的化学物质是由小分子酸溶蛋白(SASP)提供的。SASP 被认为非特异性地与DNA结合并改变其形式以防止形成 紫外线照射下的胸苷-胸苷加合物(胸苷二聚体)。这些蛋白质还提供 耐活性氧、酸、交联剂和少量耐热性。在C。 然而，艰难梭菌对这些重要蛋白质如何对C。 艰难梭菌孢子抗性谱。艰难梭菌SSPA对紫外线具有抗性，而SSPA和SspB对紫外线具有抗性 在孢子形成中起作用。艰难梭菌ΔsspAΔsspB双突变株不 产生成熟的孢子表明这些SASP在某种程度上调节产孢量 程序。本应用将从三个方面分析SASP对孢子生物学的影响。目标 1研究了SSPA和SspB如何促进孢子的形成，以及艰难梭菌如何促进孢子的形成 保护艰难梭菌基因组免受紫外线损伤。目标2研究的是 SASP有助于孢子的形成。目标3研究了降解蛋白水解酶 SASPs在萌发过程中受到调控，其在孢子中的活性谱也受到调控。成功 这些目标的完成将彻底表征SASP对孢子抗性的影响 并导致了未来可以清洁受污染环境的试剂的设计。

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.