title: ArabidopsisBax Inhibitor-1 inhibits cell death induced by pokeweed antiviral protein inSaccharomyces cerevisiae.
abstract: Apoptosis is an active form of programmed cell death (PCD) that plays critical roles in the development, differentiation and resistance to pathogens in multicellular organisms. Ribosome inactivating proteins (RIPs) are able to induce apoptotic cell death in mammalian cells. In this study, using yeast as a model system, we showed that yeast cells expressing pokeweed antiviral protein (PAP), a single-chain ribosome-inactivating protein, exhibit apoptotic-like features, such as nuclear fragmentation and ROS production. We studied the interaction between PAP and AtBI-1 (Arabidopsis thalianaBax Inhibitor-1), a plant anti-apoptotic protein, which inhibits Bax induced cell death. Cells expressing PAP and AtBI-1 were able to survive on galactose media compared to PAP alone, indicating a reduction in the cytotoxicity of PAP in yeast. However, PAP was able to depurinate the ribosomes and to inhibit total translation in the presence of AtBI-1. A C-terminally deleted AtBI-1 was able to reduce the cytotoxicity of PAP. Since anti-apoptotic proteins form heterodimers to inhibit the biological activity of their partners, we used a co-immunoprecipitation assay to examine the binding of AtBI-1 to PAP. Both full length and C-terminal deleted AtBI-1 were capable of binding to PAP. These findings indicate that PAP induces cell death in yeast and AtBI-1 inhibits cell death induced by PAP without affecting ribosome depurination and translation inhibition.
authors.affiliation: Biotechnology Center for Agriculture and the Environment and the Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ 08901-8520, USA. ; Department of Horticulture, Faculty of Agriculture, Ege University, Izmir, Turkey.
authors.forename: Birsen
authors.initials: B
authors.lastname: Çakır
authors.affiliation: Biotechnology Center for Agriculture and the Environment and the Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ 08901-8520, USA.
authors.forename: Nilgun E
authors.initials: NE
authors.lastname: Tumer
keywords: Arabidopsis thaliana Bax Inhibitor-1; apoptotic-like cell death; pokeweed antiviral protein (PAP); ribosome inactivating proteins (RIPs)