Mycobacterium smegmatis Ku binds DNA without free ends

We report here that the lysine-rich C-terminal extension of M. smegmatis Ku contacts the core protein domain as evidenced by an increase in DNA-binding affinity and a decrease in thermal stability and intrinsic tryptophan fluorescence upon its deletion. Ku deleted for this C-terminus requires free DNA ends for binding, but translocates to internal DNA sites. In contrast, full-length Ku can directly bind DNA without free ends, suggesting that this property is conferred by its C-terminus. Such binding to internal DNA sites may facilitate recruitment to sites of DNA damage. Our data also suggest that extensions beyond the shared core domain may have independently evolved to expand Ku function.
Source: BJ Gene - Category: Biochemistry Authors: Tags: BJ Gene Source Type: research