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The Arabidopsis pex12 and pex13 mutants are defective in both PTS1‐ and PTS2‐dependent protein transport to peroxisomes
Author(s) -
Mano Shoji,
Nakamori Chihiro,
Nito Kazumasa,
Kondo Maki,
Nishimura Mikio
Publication year - 2006
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2006.02809.x
Subject(s) - peroxisome , peroxisomal targeting signal , arabidopsis , biology , mutant , biogenesis , microbiology and biotechnology , transport protein , biochemistry , cytosol , organelle , membrane protein , protein targeting , receptor , gene , membrane , enzyme
Summary Peroxisome biogenesis requires various complex processes including organelle division, enlargement and protein transport. We have been studying a number of Arabidopsis apm mutants that display aberrant peroxisome morphology. Two of these mutants, apm2 and apm4 , showed green fluorescent protein fluorescence in the cytosol as well as in peroxisomes, indicating a decrease of efficiency of peroxisome targeting signal 1 (PTS1)‐dependent protein transport to peroxisomes. Interestingly, both mutants were defective in PTS2‐dependent protein transport. Plant growth was more inhibited in apm4 than apm2 mutants, apparently because protein transport was more severely decreased in apm4 than in apm2 mutants. APM2 and APM4 were found to encode proteins homologous to the peroxins PEX13 and PEX12, respectively, which are thought to be involved in transporting matrix proteins into peroxisomes in yeasts and mammals. We show that APM2/PEX13 and APM4/PEX12 are localized on peroxisomal membranes, and that APM2/PEX13 interacts with PEX7, a cytosolic PTS2 receptor. Additionally, a PTS1 receptor, PEX5, was found to stall on peroxisomal membranes in both mutants, suggesting that PEX12 and PEX13 are components that are involved in protein transport on peroxisomal membranes in higher plants. Proteins homologous to PEX12 and PEX13 have previously been found in Arabidopsis but it is not known whether they are involved in protein transport to peroxisomes. Our findings reveal that APM2/PEX13 and APM4/PEX12 are responsible for matrix protein import to peroxisomes in planta .