Characterization of the Binding Interaction between the Oncoprotein Gankyrin and a Grafted S6 ATPase

[Image: see text] A complex with the C-terminal portion of the proteosomal subunit S6 ATPase is the only available structure of a protein–protein interaction involving the oncoprotein gankyrin. However, difficulties associated with recombinant expression of S6 ATPase alone, or truncations thereof, have limited our understanding of this assembly. We replaced the C-terminal portion of FtsH from Escherichia coli with the structurally homologous C-terminal portion of S6 ATPase and used this grafted protein to characterize the gankyrin–S6 ATPase binding interaction by isothermal titration calorimetry.