Analysis of Mutant Constructs of Human BIK and their Interaction with KSHV vBCL‐2

Abstract

Kaposi's sarcoma‐associated herpesvirus (KSHV) is a skin cancer caused by a gamma‐ herpesvirus.The virus is a “tumor” transforming virus and thus often leads to cancer in the infected patient. Its association with AIDS over the past two decades has brought increased attention to the roll viral infection plays in the evolution of cancer. KSHV has been shown to interfere in one major pathway that controls cell growth, the apoptotic pathway, important for the maintenance of normal growth and development. Viruses require a live cell for survival and have evolved a mechanism to interfere with apoptosis to create immortal cell hosts. The virus expresses a protein, vBCL‐2 that interferes with pro‐apoptotic proteins and promotes tumor growth. This viral protein is a functional homology of the human Bcl2 protein and has been shown to interact with several BH3 domain containing family members. Previously we had identified an interaction between the KSHV vBcl2 protein and the human BH3 domain containing protein, BIK using the Yeast Two Hybrid System. Current studies have demonstrated critical residues in the BH3 domain of the host Bcl2 family member, BAK, that are critical for vBcl2 interaction. We generated mutants with amino acid substitutions in homologous residues in the BH3 domain of the BIK protein to elucidate the binding interface in this interaction. Using the yeast two hybrid (Y2H) assay and biochemical methods, we analyzed the effect the mutations had on the vBcl2‐hBIK interaction. Identification of the critical amino acid residues in the BH3 domain of BIK will provide valuable insight into the mechanism of viral invasion of the cell and aid in the development of drug targets to prevent tumor development.