DNA segregation during Bacillus growth and development

描述（由申请人提供）：本申请的目标是鉴定在两种不同芽孢杆菌的营养生长和孢子形成过程中活跃的质粒DNA分配系统。研究人员将利用模式生物枯草芽孢杆菌开发新的工具来阐明质粒分离的机制，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种生物及其原生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分离机制的保守元素在孢子形成过程中如何发挥作用，以确保每个孢子至少继承一个质粒拷贝。产孢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)质粒和产孢过程都不是不必要的；2)前孢子体积比母细胞小近10倍，需要高效的质粒分配系统；3)细胞特异性转录因子在产孢过程中变得活跃，从而允许开发强大的遗传和细胞生物学方法来分离产孢过程中的DNA；4)许多芽孢杆菌质粒不编码与质粒分离蛋白ParA或ParM家族相关的蛋白质，这表明新的分离机制在起作用。由于芽孢杆菌致病性菌株的质粒上编码了各种各样的毒力因子，因此了解质粒如何从一代传递到下一代对于理解这些关键毒力决定因素的进化和传播非常重要。这些研究将允许开发更好的遗传工具和质粒载体，用于操纵许多芽孢杆菌物种。

DESCRIPTION (provided by applicant): The goal of this application is to identify plasmid DNA partitioning systems that 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 conserved elements 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 compared to the mothercell demands an efficient plasmid partitioning system; 3) cell-specific transcription factors become active during sporulation, allowing the development of powerful genetic and cell biology assays for 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.