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Functional domains and dynamic assembly of the peroxin Pex14p, the entry site of matrix proteins

Ryota Itoh1, Yukio Fujiki

  • 1Department of Biology, Faculty of Sciences, Kyushu University Graduate School, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.

The Journal of Biological Chemistry
|February 7, 2006
PubMed

Insights

The peroxin Pex14p is crucial for importing proteins into peroxisomes. Its functional domains facilitate complex assembly, ensuring proper protein import and peroxisome function.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Peroxisomal matrix protein import relies on the peroxisome targeting signal (PTS) receptor-mediated pathway.
  • Pex14p is a key component of the import machinery, acting as an initial docking site for matrix proteins.

Purpose of the Study:

  • To identify the functional domains of Pex14p involved in the assembly of import site subcomplexes.
  • To elucidate the role of Pex14p oligomerization in peroxisomal localization and protein import.

Main Methods:

  • Site-directed mutagenesis
  • Size fractionation
  • Chemical cross-linking analyses
  • Complementation of pex14 Chinese hamster ovary cell mutants

Main Results:

  • The minimal region for Pex14p function in protein import spans residues 21-260.
  • A conserved N-terminal region (residues 21-70) interacts with PTS1 receptor Pex5p, Pex13p, and Pex19p.
  • Pex14p homodimerization is regulated by a coiled-coil domain (residues 156-197), and homomeric oligomerization occurs via motifs in the transmembrane segment.
  • Pex5p, Pex13p, and Pex19p bind to Pex14p homo-oligomers, with cargo-unloaded Pex5p potentially disassembling these oligomers.

Conclusions:

  • Pex14p forms distinct peroxin complexes essential for peroxisomal matrix protein import.
  • Oligomerization of Pex14p is critical for its localization to peroxisomes and its function in the import process.

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