The Hansenula polymorpha PER3 Gene Is Essential for the Import of PTS1 Proteins into the Peroxisomal Matrix

Ida J Van Der Klei,Reinder E Hilbrands,Gert Jan Swaving,Hans R Waterham,Engel G Vrieling,Vladimir I Titorenko,James M Cregg,Wim Harder,Marten Veenhuis

doi:10.1074/jbc.270.29.17229

Ida J Van Der Klei, Reinder E Hilbrands + Show 7 more

Open Access

https://doi.org/10.1074/jbc.270.29.17229

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Abstract

PER genes are essential for the assembly of peroxisomes in Hansenula polymorpha. Here we describe the PER3 gene which was cloned by functional complementation of a H. polymorpha per3 mutant. The complementing PER3 gene encodes a protein of 569 amino acids (Per3p) with a calculated mass of 63.9 kDa; Per3p belongs to the tetratricopeptide repeat protein family and is located in both the cytosol and the peroxisomal matrix. Remarkably, Per3p does not contain a known targeting signal (PTS1 or PTS2). The PER3 gene product shows similarity to the Saccharomyces cerevisiae Pas10p (40% identity) and the Pichia pastoris Pas8p (55% identity). However, their function apparently cannot be interchanged since the P. pastoris PAS8 gene failed to functionally complement a H. polymorpha per3 disruption mutant. The per3 disruption mutant contained normal but small peroxisomes in which PTS2 proteins (both homologous and heterologous) were imported. Other matrix proteins (in particular PTS1 proteins) resided in the cytosol where they were normally assembled and active. We argue that Per3p is a component of the peroxisomal import machinery and most probably shuttles matrix proteins from the cytosol to the organellar matrix.

Highlights

The per3 disruption mutant contained normal but small peroxisomes in which PTS2 proteins were imported
We argue that PER3 gene pr odu ct (Per3p) is a component of the peroxisomal import machinery and most probably shuttles matrix proteins from the cytosol to the organellar matrix
The organelles do not contain DNA and lack an independent protein synthesizing machinery; all matrix proteins are synthesized in the cytosol and subsequently sorted to the organelle

Summary

Introduction

The per disruption mutant contained normal but small peroxisomes in which PTS2 proteins (both homologous and heterologous) were imported. Other matrix proteins (in particular PTSI proteins) resided in the cytosol where they were normally assembled and active. We argue that Per3p is a component of the peroxisomal import machinery and most probably shuttles matrix proteins from the cytosol to the organellar matrix. The organelles do not contain DNA and lack an independent protein synthesizing machinery; all matrix proteins are synthesized in the cytosol and subsequently sorted to the organelle (for a review, see Ref. 2). PTS1 (located at the extreme C terminus) and PTS2, present at the N terminus and characterized by the consensus sequence. The nucleotide sequencers) reported in this paper has been submitted to the GenBank TM /EMBL Data Bank with accession numberts) U26678

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Discussion

Conclusion