Document Detail


A peroxisomal lon protease and peroxisome degradation by autophagy play key roles in vitality of Hansenula polymorpha cells.
MedLine Citation:
PMID:  17172804     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In eukaryote cells various mechanisms exist that are responsible for the removal of non-functional proteins. Here we show that in the yeast Hansenula polymorpha (H. polymorpha) a peroxisomal Lon protease, Pln, plays a role in degradation of unfolded and non-assembled peroxisomal matrix proteins. In addition, we demonstrate that whole peroxisomes are constitutively degraded by autophagy during normal vegetative growth of WT cells. Deletion of both H. polymorpha PLN and ATG1, required for autophagy, resulted in a significant increase in peroxisome numbers, paralleled by a decrease in cell viability relative to WT cells. Also, in these cells and in cells of PLN and ATG1 single deletion strains, the intracellular levels of reactive oxygen species had increased relative to WT controls. The enhanced generation of reactive oxygen species may be related to an uneven distribution of peroxisomal catalase activities in the mutant cells, as demonstrated by cytochemistry. We speculate that in the absence of HpPln or autophagy unfolded and non-assembled peroxisomal matrix proteins accumulate, which can form aggregates and lead to an imbalance in hydrogen peroxide production and degradation in some of the organelles.
Authors:
Eda Bener Aksam; Anne Koek; Jan A K W Kiel; Stefanie Jourdan; Marten Veenhuis; Ida J van der Klei
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-03-23
Journal Detail:
Title:  Autophagy     Volume:  3     ISSN:  1554-8627     ISO Abbreviation:  Autophagy     Publication Date:    2007 Mar-Apr
Date Detail:
Created Date:  2007-01-12     Completed Date:  2007-04-11     Revised Date:  2007-07-18    
Medline Journal Info:
Nlm Unique ID:  101265188     Medline TA:  Autophagy     Country:  United States    
Other Details:
Languages:  eng     Pagination:  96-105     Citation Subset:  IM    
Affiliation:
Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Haren, The Netherlands.
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MeSH Terms
Descriptor/Qualifier:
Autophagy / physiology*
Catalase / metabolism
Fungal Proteins / metabolism
Mutation / genetics
Peroxisomes / enzymology*,  ultrastructure
Phylogeny
Pichia / cytology*,  enzymology*,  growth & development,  ultrastructure
Protease La / chemistry,  metabolism*
Protein Folding
Protein Processing, Post-Translational
Reactive Oxygen Species / metabolism
Recombinant Fusion Proteins / metabolism
Solubility
Chemical
Reg. No./Substance:
0/Fungal Proteins; 0/Reactive Oxygen Species; 0/Recombinant Fusion Proteins; EC 1.11.1.6/Catalase; EC 3.4.21.53/Protease La

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