Structural basis of bilateral cleavage in Holliday junction resolution

同源重组是一种自然机制，可以发生在任何活细胞中。利用这种机制，细胞可以将DNA片段，从而将其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/她的父亲那里继承其他特征，因为它混合和匹配基因。因此，这是一个非常重要的进化过程。当两条染色体（例如，一个来自每个亲本）并排时，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的断裂DNA链上。交叉点被称为霍利迪连接点，能够在两条染色体之间上下滑动，因此最终可以在它们之间交换少量或大量DNA。我们感兴趣的是，一旦有足够的DNA在染色体之间交换，细胞用来“破坏”或“切割”霍利迪连接的机制。细胞通常使用蛋白质来切割霍利迪连接，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杂的显示EndoI如何实际上坚持霍利迪结。为了这项工作，我们想研究这个复杂的结构。我们特别想：研究EndoI / Holliday连接复合体的结构细节。在切割过程中尝试捕获中间状态并研究其结构。将这些结构与正在进行的功能研究联系起来，试图重建EndoI用于切割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.