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Structural basis for competitive interactions of Pex14 with the import receptors Pex5 and Pex19

Christian Neufeld1, Fabian V Filipp, Bernd Simon

  • 1EMBL Heidelberg, Heidelberg, Germany.

The EMBO Journal
|February 7, 2009
PubMed

Insights

Peroxisomal protein import relies on Pex14, which binds receptors Pex5 and Pex19. Structural analysis reveals competitive binding at Pex14

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Protein import into peroxisomes is crucial for cellular function.
  • Peroxisomal protein import involves complex protein-protein interactions.
  • Pex14 is a key component of the peroxisomal import machinery, interacting with Pex5 and Pex19 receptors.

Purpose of the Study:

  • To elucidate the structural basis of Pex14 interactions with Pex5 and Pex19.
  • To understand the molecular mechanisms of peroxisomal protein import.
  • To investigate how these interactions influence Pex14 localization.

Main Methods:

  • X-ray crystallography to determine the structure of the Pex14 N-terminal domain (Pex14(N)) complexed with Pex5.
  • Site-directed mutagenesis to assess the impact of mutations on protein binding.
  • In vitro binding assays to quantify Pex5 and Pex19 interactions with Pex14 variants.
  • In vivo studies to evaluate the peroxisomal membrane localization of Pex14 variants.

Main Results:

  • The N-terminal domain of Pex14 (Pex14(N)) adopts a three-helical fold.
  • Pex5 and Pex19 bind competitively to the same surface on Pex14(N) but in opposite orientations.
  • Specific conserved aromatic residues in Pex5 (WxxxF/Y) and Pex19 (F/YFxxxF) mediate these interactions.
  • Mutations in the Pex14 binding region disrupt Pex5 and/or Pex19 binding in vitro.
  • Pex14 variants with mutations in the binding region show impaired peroxisomal membrane localization in vivo.

Conclusions:

  • The N-terminal domain of Pex14 is critical for mediating interactions with import receptors Pex5 and Pex19.
  • Competitive binding and specific molecular recognition motifs dictate the interaction dynamics.
  • These interactions are essential for the correct targeting and localization of Pex14 to the peroxisomal membrane.
  • The findings provide molecular insights into a critical step of peroxisomal protein import.

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