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The cytosolic DnaJ-like protein djp1p is involved specifically in peroxisomal protein import

E H Hettema1, C C Ruigrok, M G Koerkamp

  • 1Department of Biochemistry, Academic Medical Center, 1105 AZ Amsterdam, The Netherlands.

The Journal of Cell Biology
|July 29, 1998
PubMed

Insights

The Saccharomyces cerevisiae DJP1 gene is crucial for peroxisome function. Deleting DJP1 causes peroxisomal protein mislocalization and impaired organelle growth, indicating its specific role in peroxisomal protein import.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • DJP1 gene in Saccharomyces cerevisiae encodes a cytosolic protein homologous to E. coli DnaJ.
  • DnaJ homologues function with Hsp70 chaperones in cellular processes.
  • Cytosolic J-protein mutants typically affect multiple cellular functions.

Purpose of the Study:

  • To investigate the function of the Saccharomyces cerevisiae DJP1 gene.
  • To characterize the phenotype of DJP1 gene deletion mutants.
  • To determine the specific role of Djp1p in cellular protein import.

Main Methods:

  • Gene deletion analysis of Saccharomyces cerevisiae DJP1.
  • Phenotypic characterization of peroxisome assembly and protein import.
  • Assessment of protein localization for various organelles (peroxisome, ER, nucleus, mitochondria).

Main Results:

  • DJPl deletion mutants are viable but show specific peroxisome impairment.
  • Peroxisomal matrix proteins were mislocalized to the cytoplasm.
  • Peroxisome structures showed impaired growth and varied densities; other organelle imports were normal.
  • Metabolic adaptation to carbon source changes was unaffected.

Conclusions:

  • Djp1p is specifically required for peroxisomal protein import.
  • DJP1 plays a unique role in peroxisome biogenesis and function.
  • Djp1p's function is distinct from general protein import pathways.

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