Contribution of the endoplasmic reticulum to peroxisome formation.
How peroxisomes are formed in eukaryotic cells is unknown but important for insight into a variety of diseases. Both human and yeast cells lacking peroxisomes due to mutations in PEX3 or PEX19 genes regenerate the organelles upon reintroduction of the corresponding wild-type version. To evaluate how and from where new peroxisomes are formed, we followed the trafficking route of newly made YFP-tagged Pex3 and Pex19 proteins by real-time fluorescence microscopy in Saccharomyces cerevisiae. Remarkably, Pex3 (an integral membrane protein) could first be observed in the endoplasmic reticulum (ER), where it concentrates in foci that then bud off in a Pex19-dependent manner and mature into fully functional peroxisomes. Pex19 (a farnesylated, mostly cytosolic protein) enriches first at the Pex3 foci on the ER and then on the maturing peroxisomes. This trafficking route of Pex3-YFP is the same in wild-type cells. These results demonstrate that peroxisomes are generated from domains in the ER.
Hoepfner
Dominic
D
Department of Cellular Protein Chemistry, University of Utrecht, Padualaan 8, NL-3548 CH Utrecht, The Netherlands.
Schildknegt
Danny
D
Braakman
Ineke
I
Philippsen
Peter
P
Tabak
Henk F
HF
D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D000074401:Peroxins; D020675:Peroxisomes / Q000378:metabolism* / Q000648:ultrastructure; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; C109779:PEX19 protein, S cerevisiae; C070895:PEX3 protein, S cerevisiae; D000074401:Peroxins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C054562:yellow fluorescent protein, Bacteria