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Abstract Detail


Protein Targeting and Vesicular Trafficking

Phillips, Allison [1], Suttangkakul, Anongpat [2], Chung, Taijoon [2], Vierstra, Richard [2].

The roles of the ATG12 conjugation pathway in autophagic nutrient recycling in Arabidopsis thaliana.

Autophagy is an important mechanism for non-selective intracellular recycling whereby cytosol and organelles are encapsulated in vesicles, which are then engulfed and digested by lytic vacuoles/lysosomes. In yeast, this encapsulation employs a set of autophagy (ATG) proteins that direct the conjugation of two ubiquitin-like protein tags ATG8 and ATG12 to phosphatidylethanolamine and the ATG5 protein, respectively. Formation of these adducts is necessary for autophagic vesicle formation. ATG7 and ATG10 are the two enzymes sequentially responsible for attaching ATG12 to ATG5. By reverse genetic analysis of the single Arabidopsis genes encoding ATG5, ATG7, and ATG10 and the two genes encoding ATG12, we show here that the ATG12 conjugation system is important for survival under nitrogen (N) and carbon (C) limiting growth conditions. The atg7, atg5 and atg10 mutants are hypersensitive to N and C starvation, which is accompanied by a more rapid loss of organellar and cytoplasmic proteins. However, multiple isoforms of ATG8 are elevated in the mutants and retained during this period of protein turnover, suggesting that ATG8 is consumed during autophagic turnover. Using a GFP-ATG8a fusion in combination with concanamycin A, an inhibitor of the lytic function in the vacuole, we can detect the accumulation of autophagic bodies inside the vacuole. This accumulation is enhanced by starvation but blocked in the atg mutant backgrounds. GFP-ATG8a in combination with atg mutants provides a real-time method to track autophagic vesicle dynamics during nutrient remobilization in planta.


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1 - University of Wisconsin - Madison, Department of Genetics, 425G Henry Mall, Rm 3340, Madison, WI, 53706, USA
2 - University of Wisconsin - Madison, Department of Genetics

Keywords:
autophagy
nitrogen/carbon starvation
protein degradation.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P22002
Abstract ID:139


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