Figure 2. General Steps of Nonhomologous DNA End Joining.
Ku binding to the DNA ends at a DSB improves binding by nuclease, polymerase and ligase components. Flexibility in the loading of these enzymatic components, the option to load repeatedly (iteratively), and independent processing of the two DNA end all permit mechanistic flexibility for the NHEJ process. This mechanistic flexibility is essential to permit NHEJ to handle a very diverse array of DSB end configurations and to join them. In addition to the overall mechanistic flexibility, each component exhibits enzymatic flexibility and multifunctionality, as discussed in the text.