The Ku80 C-terminus is Dispensable for DNA-PKcs-DNA Binding.

<p>A modified ELISA was used to monitor DNA-PKcs-DNA binding and was performed as described in Materials and Methods. (a) Recruitment on 30bp DNA (b) Recruitment on a 60bp DNA. (c) DNA substrate influence on DNA-PKcs-DNA binding was tested on indicated substrates. Data are reported as the mean and SD of the rate of change in absorbance at OD_370nm in 15 minutes. (a-b) Asterisks indicate statistically significant differences compared to wild type (p<0.05). (c) Differences between 60bp vs 30bp substrate were statistically significant (p<0.05). (d), DNA binding Activity of Ku on 30bp and 60bp DNA. EMSA analysis of DNA binding activity was performed as described in Materials and methods. Ku was titrated at equal concentrations with the 30bp DNA (Lanes 1–4 and 60bp DNA (lanes 5–8). Products separated via native electrophoresis and imaged on a PhosphorImager. The free DNA is indicated by the bracket, and protein-DNA complexes representing a single Ku bound to a DNA and 2 Ku molecules bound to a DNA are indicated by the arrows.