title: DNA repair defects sensitize cells to anticodon nuclease yeast killer toxins.
abstract: Killer toxins from Kluyveromyces lactis (zymocin) and Pichia acaciae (PaT) were found to disable translation in target cells by virtue of anticodon nuclease (ACNase) activities on tRNA(Glu) and tRNA(Gln), respectively. Surprisingly, however, ACNase exposure does not only impair translation, but also affects genome integrity and concomitantly DNA damage occurs. Previously, it was shown that homologous recombination protects cells from ACNase toxicity. Here, we have analyzed whether other DNA repair pathways are functional in conferring ACNase resistance as well. In addition to HR, base excision repair (BER) and postreplication repair (PRR) promote clear resistance to either, PaT and zymocin. Comparative toxin sensitivity analysis of BER mutants revealed that its ACNase protective function is due to the endonucleases acting on apurinic (AP) sites, whereas none of the known DNA glycosylases is involved. Because PaT and zymocin require the presence of the ELP3/TRM9-dependent wobble uridine modification 5-methoxy-carbonyl-methyl (mcm(5)) for tRNA cleavage, we analyzed toxin response in DNA repair mutants additionally lacking such tRNA modifications. ACNase resistance caused by elp3 or trm9 mutations was found to rescue hypersensitivity of DNA repair defects, consistent with DNA damage to occur as a consequence of tRNA cleavage. The obtained genetic evidence promises to reveal new aspects into the mechanism linking translational fidelity and genome surveillance.
authors.affiliation: Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Klassen
authors.forename: Sabrina
authors.initials: S
authors.lastname: Wemhoff
authors.forename: Jens
authors.initials: J
authors.lastname: Krause
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Meinhardt
mesh_terms: D004260:DNA Repair / Q000235:genetics*; D042822:Genomic Instability; D051548:Histone Acetyltransferases / Q000235:genetics; D055646:Killer Factors, Yeast / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity; D007716:Kluyveromyces / Q000201:enzymology* / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010843:Pichia / Q000201:enzymology* / Q000235:genetics; D014176:Protein Biosynthesis / Q000187:drug effects; D012343:RNA, Transfer / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism* / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D012359:tRNA Methyltransferases / Q000235:genetics
chemical_list: D055646:Killer Factors, Yeast; D029701:Saccharomyces cerevisiae Proteins; C087906:killer toxin, Pichia; D012343:RNA, Transfer; C480488:TRM9 protein, S cerevisiae; D012359:tRNA Methyltransferases; C526363:Elp3 protein, S cerevisiae; D051548:Histone Acetyltransferases; D012260:Ribonucleases; C049345:anticodon nuclease