Fine mapping of autophagy-related proteins during autophagosome formation in Saccharomyces cerevisiae

Autophagy is a bulk degradation system mediated by biogenesis of autophagosomes under starvation conditions. In Saccharomyces cerevisiae, a membrane sac called the isolation membrane (IM) is generated from the pre-autophagosomal structure (PAS); ultimately, the IM expands to become a mature autophag...

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Bibliographic Details
Published in:Journal of cell science Vol. 126; no. Pt 11; p. 2534
Main Authors: Suzuki, Kuninori, Akioka, Manami, Kondo-Kakuta, Chika, Yamamoto, Hayashi, Ohsumi, Yoshinori
Format: Journal Article
Language:English
Published: England 01.06.2013
Subjects:
Autophagy - physiology
Phagosomes - genetics
Phagosomes - metabolism
Phosphatidylinositol 3-Kinases - genetics
Phosphatidylinositol 3-Kinases - metabolism
Saccharomyces cerevisiae - cytology
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae - metabolism
Saccharomyces cerevisiae Proteins - genetics
Saccharomyces cerevisiae Proteins - metabolism
Ape1 complex
Starvation
PAS
Yeast
Ape1
Pre-autophagosomal structure
Endoplasmic reticulum exit sites
Rapamycin
Aminopeptidase I
VICS
Autophagy
Autophagy-related genes
ATG
Isolation membrane
ERES
Autophagosome
Vacuole-isolation membrane contact site
ISSN:1477-9137, 1477-9137
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Summary:Autophagy is a bulk degradation system mediated by biogenesis of autophagosomes under starvation conditions. In Saccharomyces cerevisiae, a membrane sac called the isolation membrane (IM) is generated from the pre-autophagosomal structure (PAS); ultimately, the IM expands to become a mature autophagosome. Eighteen autophagy-related (Atg) proteins are engaged in autophagosome formation at the PAS. However, the cup-shaped IM was visualized just as a dot by fluorescence microscopy, posing a challenge to further understanding the detailed functions of Atg proteins during IM expansion. In this study, we visualized expanding IMs as cup-shaped structures using fluorescence microscopy by enlarging a selective cargo of autophagosomes, and finely mapped the localizations of Atg proteins. The PAS scaffold proteins (Atg13 and Atg17) and phosphatidylinositol 3-kinase complex I were localized to a position at the junction between the IM and the vacuolar membrane, termed the vacuole-IM contact site (VICS). By contrast, Atg1, Atg8 and the Atg16-Atg12-Atg5 complex were present at both the VICS and the cup-shaped IM. We designate this localization the 'IM' pattern. The Atg2-Atg18 complex and Atg9 localized to the edge of the IM, appearing as two or three dots, in close proximity to the endoplasmic reticulum exit sites. Thus, we designate these dots as the 'IM edge' pattern. These data suggest that Atg proteins play individual roles at spatially distinct locations during IM expansion. These findings will facilitate detailed investigations of the function of each Atg protein during autophagosome formation.
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ISSN:1477-9137
1477-9137
DOI:10.1242/jcs.122960