Computational Analysis of the FLFP Motif in the Cell Survival Mechanism Conferred by PKCδVIII

Abstract

Protein Kinase C δ (PKCδ) is a member of the novel group of serine/threonine kinases. In humans, PKCδ exists as two isoforms with opposite effects; PKCδI is pro‐apoptotic while PKCδVIIII is a cell survival regulator. PKCδVIII varies from the canonical sequence by a 31 amino acid insertion into the hinge region of PKCδI. A highly conserved hydrophobic linear motif, FLFP, was identified in this 31 amino acid variant region that we hypothesize contributes to the pro‐survival properties of PKCδVIII. Our lab has previously demonstrated that PKCδVIII forms complexes with mitogen activated protein kinase 1 (MAPK1) and Cyclin D1. However the exact mechanism of interaction has yet to be elucidated. Work in other model systems has demonstrated MAPK1 and Cyclin D1 to interact with the FLFP motif of other proteins. Thus, it is proposed that the interactions with PKCδVIII occur at the FLFP motif. Computational analyses of the impact site‐directed mutagenesis of the FLFP motif was performed to further investigate these protein complexes. Theoretical structures of PKCδVIII (wild‐type, F339Y, L340T, F341Y, and P342N) were created using I‐TASSER; Theoretical structures of PKCδVIII utilized in docking simulations were created using QUARK. YASARA was utilized to simulate the molecular docking of PKCδVIII to MAPK1 and Cyclin D1. The binding energies resulting from the theoretical docking were analyzed and compared to the wild‐type. Subsequent site‐directed mutagenesis of the FLFP motif has contributed to further clarifying our understanding of this protein complex. The results lend further evidence to support the role of PKCδVIII in promoting cellular survival.