The ATG12-conjugating enzyme ATG10 Is essential for autophagic vesicle formation in Arabidopsis thaliana

Genetics. 2008 Mar;178(3):1339-53. doi: 10.1534/genetics.107.086199. Epub 2008 Feb 3.

Abstract

Autophagy is an important intracellular recycling system in eukaryotes that utilizes small vesicles to traffic cytosolic proteins and organelles to the vacuole for breakdown. Vesicle formation requires the conjugation of the two ubiquitin-fold polypeptides ATG8 and ATG12 to phosphatidylethanolamine and the ATG5 protein, respectively. Using Arabidopsis thaliana mutants affecting the ATG5 target or the ATG7 E1 required to initiate ligation of both ATG8 and ATG12, we previously showed that the ATG8/12 conjugation pathways together are important when plants encounter nutrient stress and during senescence. To characterize the ATG12 conjugation pathway specifically, we characterized a null mutant eliminating the E2-conjugating enzyme ATG10 that, similar to plants missing ATG5 or ATG7, cannot form the ATG12-ATG5 conjugate. atg10-1 plants are hypersensitive to nitrogen and carbon starvation and initiate senescence and programmed cell death (PCD) more quickly than wild type, as indicated by elevated levels of senescence- and PCD-related mRNAs and proteins during carbon starvation. As detected with a GFP-ATG8a reporter, atg10-1 and atg5-1 mutant plants fail to accumulate autophagic bodies inside the vacuole. These results indicate that ATG10 is essential for ATG12 conjugation and that the ATG12-ATG5 conjugate is necessary to form autophagic vesicles and for the timely progression of senescence and PCD in plants.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Apoptosis / drug effects
  • Arabidopsis / cytology*
  • Arabidopsis / drug effects
  • Arabidopsis / enzymology*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / metabolism*
  • Autophagy* / drug effects
  • Autophagy-Related Protein 12
  • Autophagy-Related Protein 5
  • Autophagy-Related Proteins
  • Carbon / pharmacology
  • DNA Fragmentation / drug effects
  • Genes, Essential
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutant Proteins / isolation & purification
  • Mutation / genetics
  • Nitrogen / pharmacology
  • Phenotype
  • Phosphoric Monoester Hydrolases / metabolism
  • Plant Leaves / cytology
  • Plant Leaves / drug effects
  • RNA, Plant / metabolism
  • Seedlings / cytology
  • Seedlings / drug effects
  • Seedlings / metabolism
  • Transgenes

Substances

  • ATG10 protein, Arabidopsis thaliana
  • ATG12 protein, Arabidopsis
  • Arabidopsis Proteins
  • Autophagy-Related Protein 12
  • Autophagy-Related Protein 5
  • Autophagy-Related Proteins
  • Mutant Proteins
  • RNA, Plant
  • Carbon
  • Atg5 protein, Arabidopsis
  • Phosphoric Monoester Hydrolases
  • Nitrogen