The inhibitory effect of KN-93 and KN-62 as a result of CaM-directed blocking animal CaMK2 and plant CDPK activation

Aim. The goal of the study was determine whether, from a molecular point of view, inhibitors KN-93 and KN-62 are capable to disrupt the functioning of plant homologs of CaMK2 and being used as tools for the experimental study of Ca2+-dependent phosphorylation in higher plants. Methods. Selected calmodulin 1 H.sapiens reference structure and reconstructed spatial structure of calcium-binding domain of CPK1 A.thaliana. We have conducted the molecular docking of calmodulin-mediated inhibitors to CaMK2: KN-93 and KN-62 for CALM1 H. sapiens and calcium-binding domain of CPK1 A. thaliana with full ligand mobility and static amino acid residues with the use of CCDC GOLD Suite. Results. We have established the presence of spatially homologous structures within CALM1 and CPK1 that might be the binding sites for KN-93 and KN-62. Performing the molecular docking we have shown the utility of those pockets from the point of binding energy for KN-93 and KN-62. We have conducted comparative analysis basing on the results of the CCDC GOLD Suite score functions (GoldScore and ASPScore). Conclusions. It has been shown that the inhibitors of animal CaMK2 - KN93 and KN62 are capable of interacting with the site of the CaM-like domain of the plant protein kinase CPK1 homologous to the similar site of animal calmodulin, which may impair its functionality. Keywords: CaMK2, CDPK, CPK1, protein kinases, molecular docking, KN-93, KN-62.