A tRNA-specific function for tRNA methyltransferase Trm10 is associated with a new tRNA quality control mechanism in Saccharomyces cerevisiae

Overexpression of Trm10 substrate tRNA^Trp rescues the trm10Δ growth defect in 5FU. Strains were grown overnight in SD-Leu media, serially fourfold diluted from a starting OD₆₀₀ of 1, plated on SD-Leu plates with indicated concentrations of 5FU, and incubated for 4 d at 30°C. (A) G₉-containing tRNAs overexpressed in the trm10Δ strain. Whether the tRNA is modified in vivo or only by purified Trm10 in vitro is indicated on the left of each figure. The modification status of tRNA^Arg(CCU) has not been determined in S. cerevisiae. S. cerevisiae tRNA^Lys(CUU) contains m²G9 and can be modified by Trm10 upon overexpression of the enzyme in vivo, but has not been tested further as a Trm10 substrate in vitro. (B) G₉-containing tRNAs overexpressed in TRM10 cells. (C) A₉-containing tRNAs overexpressed in trm10Δ cells.