DNA segregation during Bacillus growth and development

这项建议的目的是确定在这两种情况下都活跃的质粒DNA分割系统。 两种不同芽孢杆菌的营养生长和产孢量。新的工具用于阐明 将使用模式生物枯草杆菌开发潜在的质粒分离的机制，以及 然后将其应用于巨型芽孢杆菌。利用两种不同的芽孢杆菌菌株来研究这个问题将使我们能够 利用每个有机体及其本土质粒提供的独特优势，同时 保持一个重点目标，即了解微生物DNA分离的成分是如何保守的 机械在孢子形成过程中发挥作用，以确保每个孢子至少继承一个复制的质粒。 孢子形成过程中的质粒分离为研究DNA分离提供了一个有吸引力的系统 因为：1)质粒和产孢子过程都不是不必要的；2)近10倍 与母细胞相比，较小的前孔体积需要有效的质粒分割 系统；3)细胞特有的转录因子在孢子形成过程中变得活跃，允许发育。 强大的遗传和细胞生物学分析在产孢子过程中分离DNA；以及4)许多芽孢杆菌 质粒不编码与PARA或PARM分离蛋白家族相关的蛋白质， 这表明，新的分区机制正在发挥作用。因为各种各样的致病因子是 在芽孢杆菌致病菌株的质粒上编码，了解质粒是如何从一株 下一代对理解进化和传播这些关键毒力很重要 决定因素。这些研究将允许开发更好的遗传工具和有助于 操纵着许多芽孢杆菌物种。

The goal of this proposal is to identify plasmid DNA partitioning systemsthat are active during both . vegetative growth and sporulation in two different species of Bacillus. New tools for elucidating the mechanisms underlying plasmid segregation will be developed using the model organism B. subtilis, and then applied to B. megaterium. Utilizing two different Bacillus strains to study this problem will allow us to take advantage of the unique strengths that each organism and its indigenous plasmids offer, while maintaining a focused goal of understanding how conservedelements of the microbial DNA segregation machinery functions during sporulation to ensure that every spore inherits at least one copy of the plasmid. Plasmid segregation during sporulation provides an attractive system for studying DNA segregation because: 1) both the plasmids and the sporulation process are not nonessential; 2) the nearly 10 fold smaller volume of the forespore comparedto the mothercell demands an efficient plasmid partitioning system; 3) cell-specifictranscription factorsbecome active during sporulation, allowing the development of . powerful genetic and cell biology assaysfor DNA segregation during sporulation; and 4) many Bacillus plasmids do not encode proteins related to either the ParA or ParM families of plasmid segregation proteins, suggesting that novel partitioning mechanisms are at work. Since a wide variety of virulence factors are encoded on plasmids in pathogenic strains of Bacillus, understanding how plasmids are transmitted from one generation to the next is important for understanding the evolution and spread these key virulence determinants. These studies will allow the development of better genetic tools and plasmid vectors useful for manipulating many Bacillus species.