Abstract
Type-1 ribosome-inactivating protein (RIP), one of two classified types, is found in many kinds of plants and catalyzes depurination of a specific site in large rRNA, and then the ribosome loses the activity. Also it has been proposed as an antivirus protein. Recently we found rRNA apurinic site specific lyase (RALyase) in wheat germ that cleaves the phosphodiester bond at a RIP-dependent depurination site by catalysis of β-elimination reaction. Although the physiological significance of these genes in plants is not known yet, we believe that these genes are parts of a complex self-defense mechanism since causes cell death attacking the translation system. Here we report concerning the physiological role of RIP and RALyase on senescence and hypersensitive response against virus using transgenic tobaccos that are available to artificially induce these genes by dexamethasone treatment.
