Regulation of jasmonate signaling by S-nitrosylation of SCF complex components.

TEBEZ, NURIA MALENA; IGLESIAS MJ; COLMAN S; CASALONGUÉ, C.A.; TERRILE MC

Congreso; RAFV Conference 2021 XXXIII Argentinian meeting of Plant Physiology; 2021

E3 ubiquitin ligases are the enzymes responsible for the last step of the ubiquitination pathway and are implicated in nearly every aspect of plant biology. The SCF complex is the largest multimeric E3 family and is composed by four subunits: CUL1, SKP1 (ASK1 in Arabidopsis), RBX1, and F-box protein. E3 complexes are involved in the modulation of hormonal pathways and, particularly in the auxin and jasmonates (JA) signaling, the F-box proteins, TIR1 and COI1, are their self the hormone receptors. Hormone perception stabilizes TIR1 and COI1 interaction with their transcriptional repressor, Aux/IAA and JAZ respectively, promoting proteasome degradation. Previously, we demonstrated that TIR1 and ASK1 are targets of S-nitrosation, a nitric oxide (NO)-dependent post-translational modification. S-nitrosation of TIR1 and ASK1 positively regulates SCFTIR1 complex assembly and consequently, increases the degradation of Aux/IAA and activates auxin-mediated gene expression. Since ASK1 can interchangeably associates with F-box proteins of different SCF complexes, studying SCF assembly regulation is particularly relevant. In this work, we explore the modulation of JA perception through SCFCOI1 complex by different S-nitrosylation events. We demonstrated that S-nitrosation of ASK1Cys118 enhanced ASK1-COI1 interaction. Overexpression of a non-nitrosable ask1 mutant protein impaired the activation of JA-responsive genes mediated by SCFCOI1, illustrating the functional relevance of this regulation in planta. Additionally, in silico analysis positioned COI1 as a promising S-nitrosylation target. The regulation of SCF components by NO may represent a key strategy to determine the precise time and site-dependent activation of a particular hormonal transduction pathway to respond to changing environmental scenarios.Supported by CONICET, ANPYCT and UNMdP