title: Arabidopsis ABERRANT PEROXISOME MORPHOLOGY9 is a peroxin that recruits the PEX1-PEX6 complex to peroxisomes.
abstract: Peroxisomes have pivotal roles in several metabolic processes, such as the detoxification of H₂O₂ and β-oxidation of fatty acids, and their functions are tightly regulated by multiple factors involved in peroxisome biogenesis, including protein transport. This study describes the isolation of an embryonic lethal Arabidopsis thaliana mutant, aberrant peroxisome morphology9 (apem9), which is compromised in protein transport into peroxisomes. The APEM9 gene was found to encode an unknown protein. Compared with apem9 having the nucleotide substitution, the knockdown mutants showed severe defects in peroxisomal functions and plant growth. We showed that expression of APEM9 altered PEROXIN6 (PEX6) subcellular localization from the cytosol to peroxisomes. In addition, we showed that PEX1 and PEX6 comprise a heterooligomer and that this complex was recruited to peroxisomal membranes via protein-protein interactions of APEM9 with PEX6. These findings show that APEM9 functions as an anchoring protein, similar to Pex26 in mammals and Pex15p in yeast. Interestingly, however, the identities of amino acids among these anchoring proteins are quite low. These results indicate that although the association of the PEX1-PEX6 complex with peroxisomal membranes is essential for peroxisomal functions, the protein that anchors this complex evolved uniquely in plants.
authors.affiliation: Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
authors.forename: Shino
authors.initials: S
authors.lastname: Goto
authors.forename: Shoji
authors.initials: S
authors.lastname: Mano
authors.forename: Chihiro
authors.initials: C
authors.lastname: Nakamori
authors.forename: Mikio
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D017343:Genes, Plant / Q000235:genetics; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D050505:Mutant Proteins / Q000302:isolation & purification; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics; D020675:Peroxisomes / Q000378:metabolism*; D010641:Phenotype; D025941:Protein Interaction Mapping; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism; D012639:Seeds / Q000254:growth & development
chemical_list: C561081:APEM9 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D008565:Membrane Proteins; D050505:Mutant Proteins; C036483:T-DNA; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C490761:PEROXIN6 protein, Arabidopsis; C561082:PEX1 protein, Arabidopsis