The Kluyveromyces lactis γ-toxin targets tRNA anticodons
Abstract
Kluyveromyces lactis killer strains secrete a heterotrimeric toxin (zymocin), which causes an irreversible growth arrest of sensitive yeast cells. Despite many efforts, the target(s) of the cytotoxic γ-subunit of zymocin has remained elusive. Here we show that three tRNA species tRNAGlumcm5s2UUC, tRNALysmcm5s2UUU, and tRNAGlnmcm5s2UUG are the targets of γ-toxin. The toxin inhibits growth by cleaving these tRNAs at the 3′ side of the modified wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U). Transfer RNA lacking a part of or the entire mcm5 group is inefficiently cleaved by γ-toxin, explaining the γ-toxin resistance of the modification-deficient trm9, elp1-elp6, and kti11-kti13 mutants. The K. lactis γ-toxin is the first eukaryotic toxin shown to target tRNA.
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Footnotes
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Article and publication are at http://www.rnajournal.org/cgi/doi/10.1261/rna.2172105.
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- Accepted August 22, 2005.
- Received July 25, 2005.
- Copyright 2005 by RNA Society