Molecular events regulated by the Ku heterodimer in non-homologous end-joining and DNA damage signaling pathways

Ku是一种丰富的、普遍存在的因子，在进化过程中一直非常保守，因为它在从细菌到人类的所有生物中都被发现。Ku是一种由两种蛋白质组成的复合物，在修复双链DNA断裂中起着重要作用。双链DNA断裂是一种DNA损伤形式，双螺旋的两条链都断裂，导致染色体重排，最终导致基因组不稳定。虽然Ku对DNA的正常修复至关重要，但其作用方式仍不清楚。众所周知，Ku与许多在DNA修复中发挥作用的其他因素相互作用，然而，这些相互作用的细节和结果却知之甚少。利用最近获得的Ku的晶体结构，我们可以预测蛋白质中可以接触到其他蛋白质的区域。因此，我们在这些可接近的区域中的几个区域进行了突变，以测试它们是否改变Ku DNA修复功能。我们已经确定了两个Ku突变，它们改变了它对DNA损伤的反应能力。我们发现这些突变导致不同的缺陷，表明突变的 * 区域参与不同的功能。我们建议鉴定与这些Ku基序相互作用的蛋白质，并阐明它们如何在DNA修复中共同发挥作用。从长远来看，这些分析将增强我们对Ku在处理双链DNA断裂的机制中的功能的理解。

Ku is an abundant, ubiquitous factor that has been remarkably conserved throughout evolution as it has been*identified in all organisms from bacteria to man. Ku is a complex of two proteins that plays an essential role in*the repair of double-strand DNA breaks, a form of DNA damage in which both strands of the double helix*break, leading to chromosome rearrangements and, ultimately, genomic instability.*While it is understood that Ku is essential for the proper repair of DNA, its mode of action is still unclear. It is*known that Ku interacts with a number of other factors that play roles in the repair of DNA, however, the*details and the outcome of these interactions are poorly understood.****Using the crystal structure of Ku that was recently made available, we can predict regions of the protein that are*accessible to contact other proteins. Thus we have made mutations in several of these accessible regions to test*if they alter Ku DNA repair functions. We have identified two Ku mutations that alter its ability to function in*response to DNA damage. We found that these mutations result in different defects suggesting that the mutated*regions are involved in distinct functions. We propose to identify the proteins that interact with these Ku motifs****and elucidate how they function together in the repair of DNA.*In the long-term, these analyses will enhance our understanding of the functions of Ku in the mechanisms that*are set in place to deal with double-stranded DNA breaks.**