Structure of Kinetoplast DNA

锥虫的着丝体DNA （kDNA）具有非常不寻常的结构组织，由数千个被称为大环和小环的链状DNA环组成。此外，这些环状DNA分子似乎在细胞周期控制下进行复制，特别是微环，根据它们是否被复制而被分离到kDNA网络的不同区域。在不同程度的复制的kDNA网络的结构组织将被调查作为阐明控制单个网络的精确复制的机制的手段。防止复制小环的最终共价闭合从而在子网络分离之前防止其第二次复制的机制是一个特别感兴趣的问题。此外，还将探讨最大环连接到网络的方式以及弯曲的螺旋DNA片段在将重复的小环靶向到网络的特定区域中的可能作用。此外，还将寻找可能参与体内DNA网络的凝聚和组织的蛋白质。真核细胞DNA复制的机制及其与细胞周期的协调是生物学的基本问题。着丝体DNA包含两种不同类型的复制子，小环和大环，与哺乳动物线粒体DNA不同，这两种复制子都与细胞周期协调复制。此外，调控着丝体复制的基因可能在细胞核中编码，可能与控制核DNA合成的基因相似或相关。因此，着丝体DNA系统提供了一个了解真核细胞生长和分裂的基本方面的机会。

Kinetoplast DNA (kDNA) of trypanosomes has a highly unusual structural organization consisting of thousands of catenated DNA circles termed maxicircles and minicircles. In addition, these circular DNA molecules appear to replicate under cell cycle control and minicircles, in particular, are segregated into distinct domains of the kDNA network depending on whether or not they have been replicated. The structural organization of kDNA networks at different extents of replication will be investigated as a means of elucidating the mechanisms controlling the precise duplication of individual networks. The mechanisms that prevent the final covalent closure of duplicated minicircles and thereby prevent their replication a second time prior to segregation of daughter networks is of a particular interest. The manner in which maxicircles are catenated to the network and the possible role of bent helical DNA segments of minicircles in targeting duplicated minicircles to a specific domain of the network will also be explored. Additionally a search will be made for proteins that may be involved in the condensation and organization of the DNA network in vivo. The mechanism of DNA replication in eukaryotic cells and the coordination of replication with the cell cycle are fundamental problems in biology. Kinetoplast DNA contains two distinct types of replicons, minicircles and maxicircles, both of which, unlike mammalian mitochondrial DNA, are replicated coordinately with the cell cycle. In addition, the genes that regulate kinetoplast replication are likely to be encoded in the nucleus and may be similar or related to the genes controlling nuclear DNA synthesis. Thus, the kinetoplast DNA system offers an opportunity to understand fundamental aspects of the growth and division of eukaryotic cells.