Schizosaccharomyces pombe pus1 mutants are temperature sensitive due to decay of tRNA^Ile(UAU) by the 5′-3′ exonuclease Dhp1, primarily targeting the unspliced pre-tRNA

The temperature sensitivity of pus1Δ strains is suppressed if the single copy tIUAU) gene lacks its intron, or has a stabilizing U₂₇C mutation. (A) Schematic showing the predicted residues at N₂₇, N₃₄, and N₃₆ for tIUAU)-WT, tIUAU)-U27C, and tIUAU)-iΔ variants in WT and pus1Δ strains. Arrows point to explicit comparisons that can be made to assess the contributions of Ψ₂₇ versus U₂₇, U₂₇ versus C₂₇, Ψ₃₄ and Ψ₃₆ versus U₃₄, and U₃₆, and the intron versus no intron. (B) Growth properties of WT and pus1Δ strains with single integrated tIUAU) variants. The set of WT and pus1Δ strains depicted in A was constructed as described in the text. Then independent strains were grown overnight in YES media at 30°C, and then cells were serially diluted and spotted as described in Figure 1A on EMMC-Leu and YES media and incubated for 4 days and 2 days, respectively, at the indicated temperatures.