Laboratory of Molecular Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, 611-0011 Kyoto, Japan.
The DOT5 gene was originally cloned as one of the DOT (disrupter of telomeric silencing) genes; and later it was re-discovered as a nuclear thioredoxin peroxidase in Saccharomyces cerevisiae. Here, we demonstrate that the telomeric-silencing disruption activity of Dot5 is independent of thioredoxin peroxidase activity. In addition, Dot5 cannot suppress the increased susceptibility to peroxides of mutants defected in cytosolic thioredoxin peroxidase, even when Dot5 is expressed in the cytoplasm. Furthermore, Dot5 does not affect redox regulation of the Yap1 transcription factor. These results suggest that Dot5 is less important as an antioxidant in yeast cells.