Plant Catalase is Imported into Peroxisomes by Pex5p but is Distinct from Typical PTS1 Import

We have previously demonstrated that the targeting signal of pumpkin catalase, Cat1, is an internal PTS1 (peroxisomal targeting signal 1)-like sequence, QKL, located at -13 to -11 from the C-terminus, which is different from the typical PTS1 SKL motif located in the C-terminus. Here we show that Cat1 import into peroxisome is dependent on the cytosolic PTS receptor, Pex5p, in Arabidopsis, similar to typical PTS1 import, and that other components for transport of peroxisomal matrix proteins such as Pex14p, Pex13p, Pex12p and Pex10p also contribute to the import of Cat1. Interestingly, however, we found that Cat1 interacts with the N-terminal domain of Pex5p, but not the C-terminal domain for interaction with the typical PTS1, revealing that Pex5p recognizes Cat1 in a manner distinct from typical PTS1.