Functional similarity between the peroxisomal PTS2 receptor binding protein Pex18p and the N-terminal half of the PTS1 receptor Pex5p

Mol Cell Biol. 2004 Oct;24(20):8895-906. doi: 10.1128/MCB.24.20.8895-8906.2004.

Abstract

Within the extended receptor cycle of peroxisomal matrix import, the function of the import receptor Pex5p comprises cargo recognition and transport. While the C-terminal half (Pex5p-C) is responsible for PTS1 binding, the contribution of the N-terminal half of Pex5p (Pex5p-N) to the receptor cycle has been less clear. Here we demonstrate, using different techniques, that in Saccharomyces cerevisiae Pex5p-N alone facilitates the import of the major matrix protein Fox1p. This finding suggests that Pex5p-N is sufficient for receptor docking and cargo transport into peroxisomes. Moreover, we found that Pex5p-N can be functionally replaced by Pex18p, one of two auxiliary proteins of the PTS2 import pathway. A chimeric protein consisting of Pex18p (without its Pex7p binding site) fused to Pex5p-C is able to partially restore PTS1 protein import in a PEX5 deletion strain. On the basis of these results, we propose that the auxiliary proteins of the PTS2 import pathway fulfill roles similar to those of the N-terminal half of Pex5p in the PTS1 import pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl-CoA Oxidase / genetics
  • Acyl-CoA Oxidase / metabolism*
  • Biological Transport / physiology
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Humans
  • Intracellular Membranes / metabolism
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Peroxisomal Targeting Signal 2 Receptor
  • Peroxisome-Targeting Signal 1 Receptor
  • Peroxisomes / metabolism
  • Peroxisomes / ultrastructure
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*

Substances

  • Fungal Proteins
  • Membrane Transport Proteins
  • PEX18 protein, S cerevisiae
  • PEX5 protein, S cerevisiae
  • Peroxisomal Targeting Signal 2 Receptor
  • Peroxisome-Targeting Signal 1 Receptor
  • Receptors, Cytoplasmic and Nuclear
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Acyl-CoA Oxidase
  • POX1 protein, S cerevisiae