1. Atg8 is essential for macropexophagy in Hansenula polymorpha
- Author
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Monastyrska, I., van der Heide, M, Krikken, A.M., Kiel, J.A.K.W., van der Klei, I.J., Veenhuis, M, Monastyrska, [No Value], Moleculaire Celbiologie, Faculty of Science and Engineering, GBB Cluster Microbiologie, and Groningen Biomolecular Sciences and Biotechnology
- Subjects
autophagy ,methylotrophic yeast ,Recombinant Fusion Proteins ,ATG8 ,Green Fluorescent Proteins ,Molecular Sequence Data ,Saccharomyces cerevisiae ,Mutant ,Macropexophagy ,Mutagenesis (molecular biology technique) ,Biochemistry ,Pichia ,Pichia pastoris ,Fungal Proteins ,Structural Biology ,Peroxisomes ,Genetics ,Amino Acid Sequence ,Microautophagy ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Molecular Biology ,Microscopy, Confocal ,Sequence Homology, Amino Acid ,biology ,Biological Transport ,sequestration ,Cell Biology ,Peroxisome ,biology.organism_classification ,Immunohistochemistry ,Cell biology ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,peroxisome degradation ,Gene Deletion - Abstract
We have isolated a peroxisome-degradation-deficient (pdd) mutant of the methylotrophic yeast Hansenula polymorpha via gene tagging mutagenesis. Sequencing revealed that the mutant was affected in the HpATG8 gene. HpAtg8 is a protein with high sequence similarity to both Pichia pastoris and Saccharomyces cerevisiae Atg8 and appeared to be essential for selective peroxisome degradation (macropexophagy) and nitrogen-limitation induced microautophagy. Fluorescence microscopy revealed that a GFP.Atg8 fusion protein was located close to the vacuole. After induction of macropexophagy, the GFP.Atg8 containing spot extended to engulf an individual peroxisome. In cells of a constructed deletion strain, sequestration of individual organelles was never completed; analysis of series of serial sections revealed that invariably a minor diaphragm-like opening remained. We hypothesize that H. polymorpha Atg8 facilitates sealing of the sequestering membranes during selective peroxisome degradation.
- Published
- 2005