The Kluyveromyces lactis γ-toxin targets tRNA anticodons

Jian Lu, B. O. Huang, Anders Esberg, Marcus J.O. Johansson, Anders S. Byström

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


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 tRNA mcm5s2UUCGlu, tRNAmcm5s2UUULys, and tRNAmcm5s2UUGGln 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 (mcm 5s2U). 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. Published by Cold Spring Harbor Laboratory Press.

Original languageEnglish (US)
Pages (from-to)1648-1654
Number of pages7
Issue number11
StatePublished - Nov 2005
Externally publishedYes


  • 5- methoxycarbonylmethyl-2-thiouridine
  • ELP3
  • K. Lactis γ-toxin
  • TRM9
  • tRNA endonuclease

ASJC Scopus subject areas

  • Molecular Biology


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