Type 2 asparaginases, a subfamily of N-terminal nucleophile (Ntn) hydrolases, are activated by limited proteolysis. This activation yields a heterodimer and a loop region at the C-terminus of the α-subunit is released. Since this region is unresolved in all type 2 asparaginase crystal structures but is close to the active site residues, we explored this loop region in six members of the type 2 asparaginase family using homology modeling. As the loop model for the childhood cancer-relevant protease Taspase1 differed from the other members, Taspase1 activation as well as the conformation and dynamics of the 56 amino acids loop were investigated by CD and NMR spectroscopy. We propose a helix-turn-helix motif, which can be exploited as novel anticancer target to inhibit Taspase1 proteolytic activity.
We acknowledge the Fonds of Chemical Industry for funding JvdB by their Chemiefonds grant and the DFG for funding PB and CB (CRC 1093). Additional gratitude goes to Shirley Knauer for providing Taspase1 expression clones.
Funding: The authors acknowledge the Fonds of Chemical Industry for funding JvdB by their Chemiefonds grant and the DFG for funding PB and CB (CRC 1093).