title: Matrix proteins are inefficiently imported into Arabidopsis peroxisomes lacking the receptor-docking peroxin PEX14.
abstract: Mutations in peroxisome biogenesis proteins (peroxins) can lead to developmental deficiencies in various eukaryotes. PEX14 and PEX13 are peroxins involved in docking cargo-receptor complexes at the peroxisomal membrane, thus aiding in the transport of the cargo into the peroxisomal matrix. Genetic screens have revealed numerous Arabidopsis thaliana peroxins acting in peroxisomal matrix protein import; the viable alleles isolated through these screens are generally partial loss-of-function alleles, whereas null mutations that disrupt delivery of matrix proteins to peroxisomes can confer embryonic lethality. In this study, we used forward and reverse genetics in Arabidopsis to isolate four pex14 alleles. We found that all four alleles conferred reduced PEX14 mRNA levels and displayed physiological and molecular defects suggesting reduced but not abolished peroxisomal matrix protein import. The least severe pex14 allele, pex14-3, accumulated low levels of a C-terminally truncated PEX14 product that retained partial function. Surprisingly, even the severe pex14-2 allele, which lacked detectable PEX14 mRNA and PEX14 protein, was viable, fertile, and displayed residual peroxisome matrix protein import. As pex14 plants matured, import improved. Together, our data indicate that PEX14 facilitates, but is not essential for peroxisomal matrix protein import in plants.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, TX 77005, USA.
authors.forename: Melanie
authors.initials: M
authors.lastname: Monroe-Augustus
authors.forename: Naxhiely Martínez
authors.initials: NM
authors.lastname: Ramón
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Ratzel
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Lingard
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Christensen
authors.forename: Chaya
authors.initials: C
authors.lastname: Murali
authors.forename: Bonnie
authors.initials: B
authors.lastname: Bartel
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009154:Mutation; D020675:Peroxisomes / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; C499192:PEX14 protein, Arabidopsis; D012333:RNA, Messenger; D012097:Repressor Proteins