Plant ribosomal RNA apurinic site specific lyase (RALyase) cleaves the phosphodiester bond at the depurinated site produced by ribosome-inactivating protein, while the biological role of this enzyme is not clear. As the depurinated ribosomes retain weak translation elongation activities, it was suggested that RALyase completes the ribosome inactivation. To confirm this point, we measured the effects of the phosphodiester cleavage using a fusion of wheat RALyase produced with a cell-free protein synthesis system from wheat germ. The results indicated that RALyase diminishes the residual elongation activities of the depurinated ribosomes.
