Structural basis of bilateral cleavage in Holliday junction resolution

同源重组是一种自然机制，它可以在任何活细胞中发生。利用这种机制，细胞就有可能将DNA片段，也就是它的基因，从染色体上的一个位置移动到另一个位置。这是一种机制，允许一个人从他/她的母亲那里继承一些特征，从他/她的父亲那里继承另一些特征，因为它混合和匹配了基因。因此，这是一个非常重要的进化过程。当两条染色体（例如一对亲本各一条）并排在一起时，每条染色体上的一条DNA链断裂，然后连接到另一条染色体上断裂的DNA链上。交叉点，也就是所谓的霍利迪接点，能够在两条染色体之间上下滑动，这样一点点或大量的DNA最终可以在它们之间交换。我们感兴趣的是，一旦染色体之间交换了足够的DNA，细胞就会“破坏”或“切断”霍利迪结的机制。细胞通常使用蛋白质来切割Holliday连接，我们之前已经详细研究了其中一种蛋白质（EndoI）的结构。最近，我们已经能够制作一个复合体来展示EndoI是如何粘附在Holliday连接点上的。为了这项工作，我们想研究这个复合物的结构。我们特别想：详细研究EndoI / Holliday结复合体的结构。在切削过程中尝试捕获中间状态，并研究这些中间状态的结构。将这些结构与正在进行的功能研究联系起来，试图重建EndoI切断Holliday连接的确切机制。

Homologous recombination is a natural mechanism, which can take place in any living cell. Using this mechanism it is possible for the cell to move segments of DNA, and therefore its genes, from one location on a chromosome to another. This is the mechanism that allows a person to inherit some characterstics from his/her mother, and others from his/her father, as it mixes and matches the genes. It is therefore a very important evolutionary process. When two chromosomes (e.g. one form each parent) are side by side, one strand of DNA on each chromosome is broken and then attached to the broken strand of DNA on the other chromosome. The crossover point, which is called the Holliday junction, is able to slide up and down between the two chromosomes, so that a little or a lot of DNA can ultimately be switched between them. We are interested in the mechanism cell uses to 'break' or 'cut' the Holliday junction once enough DNA has been exchanged between the chromosomes. Cells typically use proteins to cut Holliday junctions and we have previously studied the structure of one of these proteins (EndoI) in fine detail. Very recently, we have been able to make a complex showing how EndoI actually sticks to a Holliday junction. For this work we would like to study the structure of this complex. We would specifically like to: Study the structure of the EndoI / Holliday junction complex in fine detail. Try and trap intermediate states during the cutting process and study the structure of these. Relate these structures to ongoing functional studies to attempt to reconstruct the exact mechanism EndoI uses to cut Holliday junctions.