Fig. 2.

tRNAs are cleaved by specific enzymes. Bacterial endonucleases, PrrC, colicin D, and colicin E5, cleave specific subsets of bacterial tRNAs of invading species in the anticodon region. A similar tRNA endonuclease activity is mediated by γ-toxin from the dairy yeast Kluyveromyces lactis, to arrest the growth of Saccharomyces cerevisiae. Under oxidative stress, tRNAs are cleaved by Rny1 in yeast and by angiogenin in mammalian cells. The nucleolytic activity of angiogenin is further regulated by RNH1, an inhibitory protein, and by tRNA methylation