Abstract

The ctt1^+ gene in Schizosaccharomyces pombe encodes a catalase responsible for H_2O_2 -resistance of this organism as judged by the H_2O_2 -sensitive phenotype of the ctt1[delta] mutant. In this study, we investigated the subcellular localization of the Ctt1 gene product. In wild type cells catalase activity was detected in the organelle fraction as well as in the cytosol. The ctt1[delta] mutant contained no catalase activity, indicating that both cytosolic and organellar catalases are the products of a single ctt1^+ gene. Western blot analysis revealed two catalase bands, both of which disappeared in the ctt1[delta] mutant. The major, faster-migrating band existed in the cytosol whereas the minor, slower-migrating band appeared to be located in organelles, most likely in peroxisomes. These results suggest that the ctt1^++ gene product targeted to the peroxisome is a modified form of the one in the cytosol.

• Keywords: catalase; ctt1^+; subcellular fractionation; peroxisome; S. pombe