Solution structure of the C-terminal domain of Ku80 suggests important sites for protein-protein interactions.

The solution structure of Ku80 CTD from residue 566 to 732 has been solved in order to gain insights into the mechanisms of its interactions with other proteins. The structure reveals a topology similar to several common scaffolds for protein-protein interactions, in the absence of significant sequence similarity to these proteins. Conserved surface amino acid residues are clustered on two main surface areas, which are likely involved in mediating interactions between Ku80 and other proteins. The Ku70/Ku80 heterodimer has been shown to be involved in at least three processes, nonhomologous end joining, transcription, and telomere maintenance, and thus it needs to interact with different proteins involved in these different processes. The three-dimensional structure of the Ku80 C-terminal domain and the availability of NMR chemical shift assignments provide a basis for further investigation of the interactions between Ku80 and other proteins in these Ku-dependent cellular functions.