DNA segregation during Bacillus growth and development

描述(申请人提供)：本申请的目标是鉴定在两种不同种类的芽孢杆菌中，在营养生长和孢子形成过程中都活跃的质粒DNA分配系统。我们将利用模式生物枯草杆菌开发新的工具来阐明导致质粒分离的机制，然后将其应用于巨大芽孢杆菌。利用两个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所提供的独特优势，同时保持一个重点的目标，即了解微生物DNA分离机制的保守元件在孢子形成过程中是如何发挥作用的，以确保每个孢子至少继承一份质粒。芽胞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)质粒和孢子形成过程都不是非必需的；2)前孔的体积比母细胞小近10倍，需要有效的质粒分离系统；3)细胞特异的转录因子在孢子形成过程中变得活跃，使得发展强大的遗传和细胞生物学方法来检测孢子形成过程中的DNA分离；以及4)许多芽孢杆菌质粒不编码与PARA或PARM质粒分离蛋白家族相关的蛋白质，这表明新的分离机制正在发挥作用。由于在芽孢杆菌致病菌株的质粒上编码了多种毒力因子，因此了解质粒是如何从一代传递到下一代的对于理解进化和传播这些关键的毒力决定因素是很重要的。这些研究将允许开发更好的遗传工具和质粒载体，有助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.