Regulation of jasmonate signaling by S-nitrosation of SCFCOI1 complex components

NURIA MALENA TEBEZ; MARÍA JOSÉ IGLESIAS; SILVANA LORENA COLMAN; CLAUDIA CASALONGUÉ; MARÍA CECILIA TERRILE

Congreso; XXXIII Argentinian meeting of Plant Physiology (RAFV2021); 2021

E3 ubiquitin ligases are 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 of four subunits: CUL1, SKP1 (ASK1 in Arabidopsis), RBX1, and F-box protein. E3 complexes are involved in the modulation of different hormonal pathways. Particularly in the auxin and jasmonate (JA) signaling, the F-box proteins, TIR1 and COI1, are themselves 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. We hypothesize that S-nitrosation of TIR1 and ASK1 positively regulates SCFTIR1 complex assembly increasing Aux/IAA repressor degradation, and consequently, activates the hormonal signaling pathway. Since ASK1 can interchangeably associate with F-box proteins from different SCF complexes, studying SCF assembly regulation is particularly relevant. In this work, we explore the regulation of JA perception by S-nitrosation of SCFCOI1 complex components. We demonstrated that S-nitrosation of ASK1 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 post-translational regulation in planta. In silico analysis also positioned COI1 as a promising S-nitrosation target. NO-mediated regulation of SCFCOI1 components may represent a key strategy to modulate the precise time and site-dependent activation of the JA transduction pathway to respond to changing environmental scenarios.