DNA segregation during Bacillus growth and development

描述(申请人提供)：这项建议的目标是确定芽孢杆菌物种中大的、低拷贝数的质粒的DNA分离的机制。通过对苏云金芽孢杆菌表达载体pBtoxis的研究，我们发现了一个属于微管蛋白超家族的新分离蛋白。TubZ是一种发散的微管蛋白样蛋白，可以组装对pBtoxis的稳定遗传至关重要的动态聚合物。微管蛋白类蛋白通常存在于芽孢杆菌的毒力质粒上，但它们如何影响质粒的稳定性尚不清楚。我们还在枯草芽孢杆菌中鉴定了几个参与质粒DNA分离的不同的肌动蛋白样蛋白家族。质粒pLS32和Alp7A的AlfA都能组装聚合物，但它们似乎通过不同的机制分离质粒。本研究的目的是了解芽孢杆菌微管蛋白和肌动蛋白的生化性质、体内组装动力学以及参与质粒DNA分离的功能。由于芽孢杆菌的致病菌株(如炭疽杆菌的pXO1)的质粒上编码了多种毒力因子，因此了解这些重要的毒力决定因素的进化和传播对于了解这些重要的毒力决定因子是如何从一代传递到下一代非常重要的。 公共卫生相关性：这项研究的重点是了解细菌质粒是如何遗传的。质粒在细菌发病机制中发挥着关键作用，因为它们通常是可传播的，并编码抗生素耐药性和毒力特征，如毒素和胶囊。因此，这些研究有助于确定新的窄谱抗生素的靶标，因为在某些感染中，阻断质粒稳定性将降低致病性。

DESCRIPTION (provided by applicant): The goal of this proposal is to identify the mechanisms of DNA segregation for large, low copy number plasmids in Bacillus species. From studying plasmid pBtoxis in Bacillus thuringiensis, we identified a novel segregation protein belonging to the tubulin superfamily. TubZ is a divergent tubulin like protein that assembles dynamic polymers essential for the stable inheritance of plasmid pBtoxis. Tubulin-like proteins are commonly found on Bacillus virulence plasmids, but how they contribute to plasmid stability is unknown. We have also identified several families of divergent actin-like proteins involved in plasmid DNA segregation in Bacillus subtilis. AlfA of plasmid pLS32 and Alp7A both assemble polymers, but they appear to segregate plasmids by different mechanisms. The goal of this proposal is to understand the biochemical properties, in vivo assembly dynamics, and the functions of Bacillus tubulins and actins involved in plasmid DNA segregation. Since a wide variety of virulence factors are encoded on plasmids in pathogenic strains of Bacillus, such as pXO1 of B. anthracis, understanding how plasmids are transmitted from one generation to the next is important for understanding the evolution and spread of these key virulence determinants. PUBLIC HEALTH RELEVANCE: This study focuses on understanding how bacterial plasmids are inherited. Plasmids play key roles in bacterial pathogenesis, as they are often transmissible and encode antibiotic resistance and virulence traits, such as toxins and capsules. These studies could therefore help identify targets for new narrow spectrum antibiotics, since blocking plasmid stability will in certain infections decrease pathogenicity.