Site specific recombination and replicon stability

在这项研究中，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，需要细胞适当地同步DNA复制和细胞分裂的事件。在这个过程中可能出现的问题之一是，当细胞分裂前细胞的DNA分子相互重组时。这导致无法有效分离的扩大的DNA分子，导致遗传物质的不均匀分布。为了抵消这个问题，细菌已经设计出一种方法，利用一种称为定点重组的遗传过程，将这些扩大的DNA分子恢复到原来的状态。这个过程发生在细胞分裂之前，确保两个子细胞获得正确数量的遗传物质。在大多数细菌中，这个过程使用两种蛋白质，称为XerC和XerD重组酶。这些蛋白质作用于染色体和质粒上的特定位置，这是负责在细菌之间传播耐药性的小染色体。除了XerC和XerD之外，还需要其他细胞蛋白来确保重组反应能够发生。尽管对这些重组系统的研究，以及它们的辅助因子。我们使用ColE1质粒作为模型来研究这个系统。ColE1使用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体，使XerC和XerD与ColE1结合并进行重组反应。*除了染色体的分离，Xer重组可能还有其他作用。我们最近发现，一个功能上的重组系统对链球菌的生长和链长很重要。我们研究的主要目的是了解XER重组复合体是如何形成的，编码这些蛋白质的基因是如何调控的，以及哪些其他细胞过程可能使用这些蛋白质。

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.