Site specific recombination and replicon stability

位点特异性重组和复制子稳定性

• 批准号: 106085-2006
• 负责人: Szatmari, George
• 金额: $ 3.22万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=362641
• 关键词: Site; specific; recombination; replicon; stability

In this study, we wish to examine how a bacteria's genetic material separates before the cell divides.  This process is very complex and requires that the cell properly synchronizes the events of DNA replication and cell division.  One of the problems that can arise during this process is when the cell's DNA molecules recombine with each other prior to cell division.  This results in an enlarged DNA molecule that cannot be effectively separated, resulting in an unequal distribution of genetic material.  To counteract this problem, bacteria have devised a way to restore  these enlarged DNA molecules into their original state using a genetic process called site-specific recombination.  This process occurs just before cell division, ensuring that both daughter cells receive the correct amount of genetic material.  In most bacteria, this process uses two proteins called the XerC and XerD recombinases.  These proteins act at specific sites on chromosomes and plasmids, which are mini-chromosomes responsible for transmission of resistance among bacteria.  In addition to XerC and XerD, other cellular proteins are required to ensure that the recombination reaction can occur.  It is the study of these recombination systems, and their accessory factors that interests our laboratory.  We use the ColE1 plasmid as a model to study this system.  ColE1 uses ArgR and PepA as accessory factors for the XerC and XerD proteins.  We believe that ArgR and PepA act together to form a presynaptic complex, which allows XerC and XerD to bind to ColE1 and perform the recombination reaction.  In addition to the separation of chromosomes, the Xer recombination may have other effects.  We have recently found that a functional recombination system is important for growth and chain length in streptococcal bacteria, and may also contribute to the pathogenicity of these bacteria.  The main thrust of our research is to understand how the Xer recombination complex forms, how the genes encoding these proteins are regulated, and what other cellular processes may use these proteins.

在本研究中，我们希望研究细菌的遗传物质在细胞分裂之前是如何分离的。这一过程非常复杂，需要细胞正确地进行DNA复制和细胞分裂。在这一过程中可能出现的问题之一是细胞的DNA分子在细胞分裂之前相互重组。这导致了一个扩大的DNA分子，有效地分离，导致遗传物质的不均匀分布。为了解决这个问题，细菌设计了一种方法，使用称为位点特异性重组的遗传过程将这些放大的DNA分子恢复到原始状态。这个过程发生在细胞分裂之前，确保两个子细胞接收正确数量的遗传物质。在大多数细菌中，这一过程使用两种称为XerC和XerD重组酶的蛋白质。这些蛋白质作用于染色体和质粒上的特定位点，染色体和质粒是负责在细菌之间传递抗性的微型染色体。除了XerC和XerD，还需要其他细胞蛋白质来确保重组反应能够发生。正是对这些重组系统的研究，我们以ColE1质粒为模型研究了这一系统。ColE1以ArgR和PepA作为XerC和XerD蛋白的辅助因子。我们认为ArgR和PepA共同作用形成突触前复合物，使XerC和XerD与ColE1结合并进行重组反应。除了染色体分离外，Xer重组可能有其他作用。我们最近发现，一个功能性重组系统对链球菌的生长和链长很重要，也可能有助于这些细菌的致病性。我们研究的主要目的是了解Xer重组复合物是如何形成的，编码这些蛋白质的基因是如何调节的，以及其他细胞过程可能使用这些蛋白质。