Mechanism of Translation Inhibition and mRNA destabilization by Pokeweed Antiviral Protein

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

Ribosome inactivating proteins (RIPs) are protein toxins produced by organisms ranging from bacteria to plants. RIPs have become important agents in agriculture and medicine mainly by virtue of their broad-spectrum antiviral activity and cytocidal properties against cancer cells, however their therapeutic potential has been limited because of their undesirable side effects. Their potent toxicity has been exploited in biological warfare and more recently in bioterrorism. The plant RIPs, ricin and pokeweed antiviral protein (PAP), depurinate the highly conserved sarcin/ricin (S/R) loop of the large rRNA and inhibit translation. The mechanism by which RIPs inhibit translation and cell growth is not entirely understood. This project uses PAP as a tool to understand the mode of action of RIPs. Besides depurinating the rRNA, PAP binds to the cap structure and depurinates capped, but not uncapped RNAs. This project will test the hypothesis that PAP inhibits elongation as well as re-initiation of protein synthesis by breaking the interaction between the cap and the poly(A) tail of the mRNA. The functional relationship between rRNA depurination, cap binding and translation inhibition will be analyzed to determine if PAP affects the cap-dependent translation initiation complex. This project will contribute to our basic understanding of the mechanisms that regulate cellular translation. It will provide an interdisciplinary training opportunity and will be integrated into undergraduate and graduate courses to expose students to the state-of-the-art methods in post-transcriptional control of gene expression.