A fungal anticodon nuclease ribotoxin exploits a secondary cleavage site to evade tRNA repair.

ABSTRACT: PaOrf2 and γ-toxin subunits of Pichia acaciae toxin (PaT) and Kluyveromyces lactis zymocin are tRNA anticodon nucleases. These secreted ribotoxins are assimilated by Saccharomyces cerevisiae, wherein they arrest growth by depleting specific tRNAs. Toxicity can be recapitulated by induced intracellular expression of PaOrf2 or γ-toxin in S. cerevisiae. Mutational analysis of γ-toxin has identified amino acids required for ribotoxicity in vivo and RNA transesterification in vitro. Here, we report that PaOrf2 residues Glu9 and His287 (putative counterparts of γ-toxin Glu9 and His209) are essential for toxicity. Our results suggest a similar basis for RNA transesterification by PaOrf2 and γ-toxin, despite their dissimilar primary structures and distinctive tRNA target specificities. PaOrf2 make

SUBMITTER: Meineke B 

PROVIDER: S-EPMC3425785 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature