Abstract
In germinating cotyledons of some oilseed plants, peroxisomes are directly changed from glyoxysomes to leaf peroxisomes. The glyoxisomal enzymes are specifically degraded during the transition. It is indicated that the putative proteases participated in the elimination of pre-existing enzymes of glyoxysomes. Peroxisomal proteases could also be involved in the processing of newly synthesized peroxisomal enzymes including thiolase and citrate synthase, which have N-terminal presequences function as a targeting signal. The presequences are cleaved by putative processing proteases localized in the peroxisomal matrix. Despite of many former studies these proteases have not been identified. In Arabidopsis, we found a protease-like protein containing putative peroxisomal targeting signal at its C-terminal end, which was highly homologous to bacterial and yeast mitochondrial ATP-dependent Lon protease. Cell fractionation studies showed that the protease-like protein localized in peroxisomes. We analyzed the molecular features of this protein using the recombinant protein technique and will discuss its functions.
