Importance of sequences adjacent to the terminal tripeptide in the import of a peroxisomal Candida tropicalis protein in plant peroxisomes

The peroxisome targeting signal (PTS) required for import of the rat acyl-C oA oxidase (AOX; EC 1.3.3.6) and the Candida tropicalis multifunctional pro tein (MFP) in plane peroxisomes was assessed in transgenic Arabidopsis thal iana (L.) Heynh. The native rat AOX accumulated in peroxisomes in A. thalia na cotyledons and targeting was dependent on the presence of the C-terminal tripeptide S-K-L. In contrast, the native C. tropicalis MFP, containing th e consensus PTS sequence A-K-I was not targeted to plant peroxisomes. Modif ication of the carboxy terminus to the S-K-L tripeptide also failed to deli ver the MFP to peroxisomes while addition of the last 34 amino acids of the Brassica napus isocitrate lyase, containing the terminal tripeptide S-R-M, enabled import of the fusion protein into peroxisomes. These results under line the influence of the amino acids adjacent to the terminal tripeptide o f the C. tropicalis MFP on peroxisomal targeting, even in the context of a protein having a consensus PTS sequence S-K-L.