title: 14-3-3 regulates 1-aminocyclopropane-1-carboxylate synthase protein turnover in Arabidopsis.
abstract: 14-3-3 proteins are a family of conserved phospho-specific binding proteins involved in diverse physiological processes. Plants have large 14-3-3 gene families, and many binding partners have been identified, though relatively few functions have been defined. Here, we demonstrate that 14-3-3 proteins interact with multiple 1-aminocyclopropane-1-carboxylate synthase (ACS) isoforms in Arabidopsis thaliana. ACS catalyzes the generally rate-limiting step in the biosynthesis of the phytohormone ethylene. This interaction increases the stability of the ACS proteins. 14-3-3s also interact with the ETHYLENE-OVERPRODUCER1 (ETO1)/ETO1-LIKE (EOLs), a group of three functionally redundant proteins that are components of a CULLIN-3 E3 ubiquitin ligase that target a subset of the ACS proteins for rapid degradation by the 26S proteasome. In contrast with ACS, the interaction with 14-3-3 destabilizes the ETO1/EOLs. The level of the ETO1/EOLs in vivo plays a role in mediating ACS protein turnover, with increased levels leading to a decrease in ACS protein levels. These studies demonstrate that regulation of ethylene biosynthesis occurs by a mechanism in which 14-3-3 proteins act through a direct interaction and stabilization of ACS and through decreasing the abundance of the ubiquitin ligases that target a subset of ACS proteins for degradation.
authors.affiliation: Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280, USA.
authors.forename: Gyeong Mee
authors.initials: GM
authors.lastname: Yoon
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Kieber
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004795:Enzyme Stability; D005030:Ethylenes / Q000096:biosynthesis; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D025941:Protein Interaction Mapping; D021381:Protein Transport; D059748:Proteolysis; D011523:Protoplasts / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D048948:14-3-3 Proteins; D029681:Arabidopsis Proteins; C485242:ETO1 protein, Arabidopsis; D005030:Ethylenes; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D010455:Peptides; C527524:R18 peptide; C036216:ethylene; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase