title: Removal of Pex3p is an important initial stage in selective peroxisome degradation in Hansenula polymorpha.
abstract: Selective degradation of peroxisomes (macropexophagy) in Hansenula polymorpha involves the sequestration of individual organelles to be degraded by membranes prior to the fusion of this compartment with the vacuole and subsequent degradation of the whole organelle by vacuolar hydrolases. Here we show that Pex3p, a peroxisomal membrane protein essential for peroxisome biogenesis, escapes this autophagic process. Upon induction of macropexophagy, Pex3p is removed from the organelle tagged for degradation prior to its sequestration. Our data indicate that Pex3p degradation is essential to allow the initiation of the organellar degradation process. Also, in a specific peroxisome degradation-deficient (pdd) mutant in which sequestration still occurs but the vacuolar fusion event is disturbed, the turnover of Pex3p is still observed. Taken together, our data suggest that degradation of Pex3p is part of the initial degradation machinery of individual peroxisomes.
authors.affiliation: Eukaryotic Microbiology, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Biological Center, P. O. Box 14, 9750 AA Haren, The Netherlands.
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Bellu
authors.forename: Florian A
authors.initials: FA
authors.lastname: Salomons
authors.forename: Jan A K W
authors.initials: JA
authors.lastname: Kiel
authors.forename: Marten
authors.initials: M
authors.lastname: Veenhuis
authors.forename: Ida J
authors.initials: IJ
authors.lastname: Van Der Klei
mesh_terms: D018528:ATP-Binding Cassette Transporters; D003546:Cysteine Endopeptidases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004791:Enzyme Inhibitors; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D007976:Leupeptins / Q000494:pharmacology; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D000074401:Peroxins; D020675:Peroxisomes / Q000378:metabolism* / Q000648:ultrastructure*; D010843:Pichia / Q000145:classification / Q000502:physiology* / Q000648:ultrastructure; D046988:Proteasome Endopeptidase Complex; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity
chemical_list: D018528:ATP-Binding Cassette Transporters; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D007976:Leupeptins; D008565:Membrane Proteins; D009097:Multienzyme Complexes; C070895:PEX3 protein, S cerevisiae; D000074401:Peroxins; C406793:SPF1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde