title: The Arabidopsis thaliana ACBP3 regulates leaf senescence by modulating phospholipid metabolism and ATG8 stability.
abstract: Bulk degradation and nutrient recycling are events associated with autophagy. The core components of the autophagy machinery have been elucidated recently using molecular and genetic approaches. In particular, two ubiquitin-like proteins, ATG8 and ATG12, which conjugate with phosphatidylethanolamine (PE) and ATG5, respectively, forming ATG8-PE and ATG12-ATG5 complexes, were shown to be essential in autophagosome formation. Our recent findings reveal that the Arabidopsis thaliana acyl-CoA-binding protein ACBP3 binds the phospholipid PE in vitro and that ACBP3 overexpression and downregulation correlate with PE composition in rosettes. Furthermore, ACBP3-overexpressors (ACBP3-OEs) display accelerated salicylic acid-dependent leaf senescence resembling the phenotype of Arabidopsis knockout (KO) mutants defective in autophagy-related (ATG) proteins. Consistently, downregulation of ACBP3 (ACBP3-KOs) delays dark-induced leaf senescence. By analysis of transgenic Arabidopsis expressing GFP-ATG8e as well as those co-expressing ACBP3-OE and GFP-ATG8e, we showed that ACBP3-overexpression disrupts autophagosome formation and enhanced degradation of ATG8 under starvation conditions, suggesting that ACBP3 is an important regulator of the ATG8-PE complex via its interaction with PE. Here, a working model for the role of ACBP3 in the regulation of autophagy-mediated leaf senescence is presented.
authors.affiliation: School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Xiao
authors.forename: Mee-Len
authors.initials: ML
authors.lastname: Chye
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001343:Autophagy; D002352:Carrier Proteins / Q000378:metabolism*; D016922:Cellular Senescence; D008954:Models, Biological; D010588:Phagosomes / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D018515:Plant Leaves / Q000166:cytology* / Q000378:metabolism; D055550:Protein Stability
chemical_list: C513212:ACBP3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D010743:Phospholipids