AUTOPHAGY-RELATED11 Plays a Critical Role in General Autophagy- and
Senescence-Induced Mitophagy in Arabidopsis |
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Authors: | Faqiang Li Taijoon Chung Richard D Vierstra |
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Institution: | Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706 |
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Abstract: | Autophagy-mediated turnover removes damaged organelles and unwanted cytoplasmic
constituents and thus plays critical roles in cellular housekeeping and nutrient
recycling. This “self eating” is tightly regulated by the
AUTOPHAGY-RELATED1/13 (ATG1/13) kinase complex, which connects metabolic and
environmental cues to the vacuolar delivery of autophagic vesicles. Here, we describe
the Arabidopsis thaliana accessory proteins ATG11 and ATG101, which
help link the ATG1/13 complex to autophagic membranes. ATG11 promotes vesicle
delivery to the vacuole but is not essential for synthesizing the ATG12-ATG5 and
ATG8-phosphatidylethanolamine adducts that are central to autophagic vesicle
assembly. ATG11, ATG101, ATG1, and ATG13 colocalize with each other and with ATG8,
with ATG1 tethered to ATG8 via a canonical ATG8-interacting motif. Also, the presence
of ATG11 encourages starvation-induced phosphorylation of ATG1 and turnover of ATG1
and ATG13. Like other atg mutants, ATG11-deficient plants senesce
prematurely and are hypersensitive to nitrogen and fixed-carbon limitations.
Additionally, we discovered that the senescence-induced breakdown of
mitochondria-resident proteins and mitochondrial vesicles occurs via an autophagic
process requiring ATG11 and other ATG components. Together, our data indicate that
ATG11 (and possibly ATG101) provides important scaffolds connecting the ATG1/13
complex to both general autophagy and selective mitophagy. |
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