Targeting signal of the peroxisomal catalase in the methylotrophic yeastHansenula polymorpha

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Abstract
The methylotrophic yeast,Hansenula polymorpha, harbours a unique catalase (EC 1,11,1,6), which is essential for growth on methanol as a carbon source and is located in peroxisomes. Its corresponding gene has been cloned and the nucleotide sequence determined. The deduced amino acid sequence displayed the tripeptide serine‐lysine‐isoleucine at the extreme C‐terminus, which is similar to sequences of other peroxisomal targeting signals. Exchange of the ultimate amino acid, isoleucine, of catalase for serine revealed a cytosolic enzyme activity and a concomitant loss of peroxisome function. We concluded that the tripeptide is essential for targeting of catalase inH. polymorpha.