Crystal Structure Of The Kinase Domain Of RNA-dependent Protein Kinaseand The Initial Research Of The Active Site Of PBK

Objective:RNA-dependent protein kinase (PKR) is crucial for the innate immune response, cellgrowth, proliferation, signal transduction and apoptosis. The activation process of PKR has beenstudied for many years and is still under debate. To obtain new insight into the mechanism ofPKR activation and substrate recognition, we made the following research.Methods:we expressed different truncations and mutations of RNA-dependent protein kinase (PKR)with the vector PET-28a, and got the crystal of PK-KDR(K296R) at a resolution of2.9,Analytical ultracentrifugation experiments, electrostatic surface maps and other methodsillustrated the dimerization of PKR.Results:we solved the crystal structure of a latent mutant of the PKR kinase domain (PKR-KD) inthe apo form at a resolution of2.9. The overall structure of PKR-KD is similar to previouslyreported structures. Structural analysis revealed a classical back-to-back dimer and a newlydefined face-to-face dimer. Analytical ultracentrifugation experiments, electrostatic surface mapsand the model of PKR-KD in complex with the eIF2α substrate all support that the face-to-facedimer is more reflective of PKR in solution, which seems to be more consistent with biochemicaldate.Conclusion:Our results provide new information (face-to-face dimer) for PKR dimerization and itsactivation mechanism.