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Biochim Biophys Acta Mol Cell Res. 2017 Oct;1864(10):1656-1667. doi: 10.1016/j.bbamcr.2017.05.021. Epub 2017 May 26.

Saccharomyces cerevisiae cells lacking Pex3 contain membrane vesicles that harbor a subset of peroxisomal membrane proteins.

Author information

1
Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (BBA), University of Groningen, PO Box 11103, 9300 CC Groningen, The Netherlands.
2
Systembiochemie, Institut für Biochemie und Pathobiochemie, Medizinische Fakultät, Ruhr-Universität Bochum, 44801 Bochum, Germany.
3
Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
4
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
5
Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Germany.
6
Systembiochemie, Institut für Biochemie und Pathobiochemie, Medizinische Fakultät, Ruhr-Universität Bochum, 44801 Bochum, Germany. Electronic address: ralf.erdmann@rub.de.
7
Molecular Cell Biology, Groningen Biomolecular Sciences and Biotechnology Institute (BBA), University of Groningen, PO Box 11103, 9300 CC Groningen, The Netherlands. Electronic address: i.j.van.der.klei@rug.nl.

Abstract

Pex3 has been proposed to be important for the exit of peroxisomal membrane proteins (PMPs) from the ER, based on the observation that PMPs accumulate at the ER in Saccharomyces cerevisiae pex3 mutant cells. Using a combination of microscopy and biochemical approaches, we show that a subset of the PMPs, including the receptor docking protein Pex14, localizes to membrane vesicles in S. cerevisiae pex3 cells. These vesicles are morphologically distinct from the ER and do not co-sediment with ER markers in cell fractionation experiments. At the vesicles, Pex14 assembles with other peroxins (Pex13, Pex17, and Pex5) to form a complex with a composition similar to the PTS1 import pore in wild-type cells. Fluorescence microscopy studies revealed that also the PTS2 receptor Pex7, the importomer organizing peroxin Pex8, the ubiquitin conjugating enzyme Pex4 with its recruiting PMP Pex22, as well as Pex15 and Pex25 co-localize with Pex14. Other peroxins (including the RING finger complex and Pex27) did not accumulate at these structures, of which Pex11 localized to mitochondria. In line with these observations, proteomic analysis showed that in addition to the docking proteins and Pex5, also Pex7, Pex4/Pex22 and Pex25 were present in Pex14 complexes isolated from pex3 cells. However, formation of the entire importomer was not observed, most likely because Pex8 and the RING proteins were absent in the Pex14 protein complexes. Our data suggest that peroxisomal membrane vesicles can form in the absence of Pex3 and that several PMPs can insert in these vesicles in a Pex3 independent manner.

KEYWORDS:

Endoplasmic reticulum; Organelle; Peroxisomal membrane protein; Peroxisome; Pex3; Protein sorting; Saccharomyces cerevisiae; Yeast

PMID:
28552664
DOI:
10.1016/j.bbamcr.2017.05.021
[Indexed for MEDLINE]
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