title: Nitric oxide influences auxin signaling through S-nitrosylation of the Arabidopsis TRANSPORT INHIBITOR RESPONSE 1 auxin receptor.
abstract: Previous studies have demonstrated that auxin (indole-3-acetic acid) and nitric oxide (NO) are plant growth regulators that coordinate several plant physiological responses determining root architecture. Nonetheless, the way in which these factors interact to affect these growth and developmental processes is not well understood. The Arabidopsis thaliana F-box proteins TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB) are auxin receptors that mediate degradation of AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) repressors to induce auxin-regulated responses. A broad spectrum of NO-mediated protein modifications are known in eukaryotic cells. Here, we provide evidence that NO donors increase auxin-dependent gene expression while NO depletion blocks Aux/IAA protein degradation. NO also enhances TIR1-Aux/IAA interaction as evidenced by pull-down and two-hybrid assays. In addition, we provide evidence for NO-mediated modulation of auxin signaling through S-nitrosylation of the TIR1 auxin receptor. S-nitrosylation of cysteine is a redox-based post-translational modification that contributes to the complexity of the cellular proteome. We show that TIR1 C140 is a critical residue for TIR1-Aux/IAA interaction and TIR1 function. These results suggest that TIR1 S-nitrosylation enhances TIR1-Aux/IAA interaction, facilitating Aux/IAA degradation and subsequently promoting activation of gene expression. Our findings underline the importance of NO in phytohormone signaling pathways.
authors.affiliation: Instituto de Investigaciones Biológicas, UE-CONICET-UNMDP, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250, CC 1245, 7600 Mar del Plata, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Terrile
authors.forename: Ramiro
authors.initials: R
authors.lastname: París
authors.forename: Luz I A
authors.initials: LI
authors.lastname: Calderón-Villalobos
authors.forename: María J
authors.initials: MJ
authors.lastname: Iglesias
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Lamattina
authors.forename: Mark
authors.initials: M
authors.lastname: Estelle
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Casalongué
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D003545:Cysteine / Q000378:metabolism; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D030821:Plants, Genetically Modified; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D059748:Proteolysis; D018749:RNA, Plant / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D016415:Sequence Alignment; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation
chemical_list: D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D018749:RNA, Plant; D011956:Receptors, Cell Surface; C501405:TIR1 protein, Arabidopsis; D009569:Nitric Oxide; D003545:Cysteine