Figure 7.

A mitochondria-dependent ROS signal controls translational accuracy. (a) Deletion of cox4, a nuclear encoded subunit of the mitochondrial complex IV, increases amino acid misincorporation but slightly decreases stop-codon read-through. This effect is rescued in a cox4 yno1 double mutant, in which the accumulation of ROS resulting from the cox4 deletion is prevented. (b) Impaired function of complex II (coq2), as well as removal of mitochondrial DNA (rho⁰), produces an increase in amino acid misincorporation similar to cox4 deletion. (c) Increases in intracellular ROS concentration by external application of H₂O₂, or by deletion of genes that encode ROS-removing activities, produce similar effects as deletion of cox4. Bars indicate averages and standard deviations for eight (a,b) or six (c) independent transformants. Statistical significance as determined by one-way ANOVA and post hoc analyses (Tukey's HSD) are indicated as follows: n.s., p > 0.05; *p < 0.05; ***p < 0.001.