MAPK phosphorylation-induced stabilization of ACS6 protein is mediated by the non-catalytic C-terminal domain, which also contains the cis-determinant for rapid degradation by the 26S proteasome pathway

摘要: Ethylene is an important hormone in plant growth, development and responses to environmental stimuli. The ethylene-signaling pathway initiated by the induction of ethylene biosynthesis, which under tight regulation at both transcriptional post-transcriptional levels exogenous endogenous cues. 1-Aminocyclopropane-1-carboxylic acid synthase (ACS) rate-limiting enzyme that catalyzes committing step biosynthesis. Recently, we found ACS2 ACS6, two isoforms Arabidopsis ACS family, are substrates a stress-responsive mitogen-activated protein kinase (MAPK) cascade. Phosphorylation ACS2/ACS6 MPK6 leads accumulation proteins ethylene. In this report, demonstrate unphosphorylated ACS6 rapidly degraded 26S proteasome pathway. degradation machinery targets C-terminal non-catalytic domain sufficient confer instability green fluorescent luciferase reporters. introduces negative charges C-terminus reduces turnover machinery. Consistent with this, other nearby conserved negatively charged amino residues essential for stability regulation. Protein phosphorylation post-translational modifications proteins. This research reveals intricate interplay between these processes controlling cellular activity, thus nature ensures rapid response induction, detectable within minutes after plants exposed stress.