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Atg8 is Essential for Macropexophagy in Hansenula polymorpha
Author(s) -
Monastyrska Iryna,
Van Der Heide Meis,
Krikken Arjen M.,
Kiel Jan A.K.W.,
Van Der Klei Ida J.,
Veenhuis Marten
Publication year - 2005
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2004.00252.x
Subject(s) - atg8 , biology , saccharomyces cerevisiae , peroxisome , mutant , yeast , vacuole , green fluorescent protein , organelle , microbiology and biotechnology , biochemistry , mutagenesis , pichia pastoris , gene , autophagy , recombinant dna , cytoplasm , apoptosis
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.