Processing of ATG8s, Ubiquitin-Like Proteins, and Their Deconjugation by ATG4s Are Essential for Plant Autophagy
AUTOR(ES)
Yoshimoto, Kohki
FONTE
American Society of Plant Biologists
RESUMO
Autophagy is an intracellular process for vacuolar degradation of cytoplasmic components. Thus far, plant autophagy has been studied primarily using morphological analyses. A recent genome-wide search revealed significant conservation among autophagy genes (ATGs) in yeast and plants. It has not been proved, however, that Arabidopsis thaliana ATG genes are required for plant autophagy. To evaluate this requirement, we examined the ubiquitination-like Atg8 lipidation system, whose component genes are all found in the Arabidopsis genome. In Arabidopsis, all nine ATG8 genes and two ATG4 genes were expressed ubiquitously and were induced further by nitrogen starvation. To establish a system monitoring autophagy in whole plants, we generated transgenic Arabidopsis expressing each green fluorescent protein–ATG8 fusion (GFP-ATG8). In wild-type plants, GFP-ATG8s were observed as ring shapes in the cytoplasm and were delivered to vacuolar lumens under nitrogen-starved conditions. By contrast, in a T-DNA insertion double mutant of the ATG4s (atg4a4b-1), autophagosomes were not observed, and the GFP-ATG8s were not delivered to the vacuole under nitrogen-starved conditions. In addition, we detected autophagic bodies in the vacuoles of wild-type roots but not in those of atg4a4b-1 in the presence of concanamycin A, a V-ATPase inhibitor. Biochemical analyses also provided evidence that autophagy in higher plants requires ATG proteins. The phenotypic analysis of atg4a4b-1 indicated that plant autophagy contributes to the development of a root system under conditions of nutrient limitation.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=527192Documentos Relacionados
- The ubiquitin-like proteins SMT3 and SUMO-1 are conjugated by the UBC9 E2 enzyme
- Specific and Covalent Targeting of Conjugating and Deconjugating Enzymes of Ubiquitin-Like Proteins
- Modification of the human thymine-DNA glycosylase by ubiquitin-like proteins facilitates enzymatic turnover
- Structural determinants for the binding of ubiquitin-like domains to the proteasome
- Structure and Evolution of Genes Encoding Polyubiquitin and Ubiquitin-like Proteins in Arabidopsis Thaliana Ecotype Columbia