Replication initiation of the second bacterial chromosome of Vibrio cholerae

基因组复制和传递是生命的特征，这些过程依赖于几种高度受控的机制。这些机制中的第一个是复制的启动。有趣的是，至少有10%的细菌具有多部分基因组，由一条主染色体和一至几条次染色体组成，称为染色质。色素是必不可少的，它们的忠实传递对细菌的生存能力是不可或缺的。因此，需要与细胞周期协调地严格控制它们的复制。虽然细菌主染色体复制起始的机制已被很好地描述，但对次级染色体复制起始的机制仍知之甚少。霍乱弧菌染色体是次级染色体的典范，其复制起始依赖于特异性因子RctB。然而，其复制起始的机制以及所涉及的DNA和蛋白质伴侣至多是表面上已知的。在这个项目中，我们的目标是确定机制，合作伙伴和细胞周期的这个重要阶段的不同步骤，从分子到细胞水平，通过生物化学和单分子实验与遗传实验相结合，在体外重建这个过程。

Genome replication and transmission are the characteristics of life, and these processes rely on several highly controlled mechanisms. The first of these mechanisms is the initiation of the replication. Interestingly, at least 10% of bacteria have a multipartite genome, composed of one main chromosome and of one to several secondary chromosomes, called chromids. Chromids are essential and their faithful transmission is indispensable to bacterial viability. Thus, a tight control of their replication in coordination with the cell cycle is required. While the mechanism for the main bacterial chromosome replication initiation is well described, the one for secondary chromosome is still poorly understood. The Vibrio cholerae chromid is the paradigm of secondary chromosomes and its replication initiation relies on the specific factor RctB. However, the mechanisms underlying its replication initiation, as well as the DNA and protein partners involved are at most superficially known. In this project, we aim at determining the mechanisms, the partners and the different steps of this essential stage of the cell cycle, from the molecular to the cellular levels by combining biochemical and single molecule experiments with genetic experiments in collaboration, up to the reconstitution of this process in vitro.