Inactivation of PYR/PYL/RCAR ABA receptors by tyrosine nitration may enable rapid inhibition of ABA signaling by nitric oxide in plants.
Abscisic acid (ABA) is a phytohormone that inhibits growth and enhances adaptation to stress in plants. ABA perception and signaling rely on its binding to receptors of the pyrabactin resistance1/PYR1-like/regulatory components of ABA receptors (PYR/PYL/RCAR) family, the subsequent inhibition of clade A type 2C protein phosphatases (PP2Cs), and the phosphorylation of ion channels and transcription factors by protein kinases of the SnRK2 family. Nitric oxide (NO) may inhibit ABA signaling because NO-deficient plants are hypersensitive to ABA. Regulation by NO often involves posttranslational modification of proteins. Mass spectrometry analysis of ABA receptors expressed in plants and recombinant receptors modified in vitro revealed that the receptors were nitrated at tyrosine residues and S-nitrosylated at cysteine residues. In an in vitro ABA-induced, PP2C inhibition assay, tyrosine nitration reduced receptor activity, whereas S-nitrosylated receptors were fully capable of ABA-induced inhibition of the phosphatase. PYR/PYL/RCAR proteins with nitrated tyrosine, which is an irreversible covalent modification, were polyubiquitylated and underwent proteasome-mediated degradation. We propose that tyrosine nitration, which requires NO and superoxide anions, is a rapid mechanism by which NO limits ABA signaling under conditions in which NO and reactive oxygen species are both produced.
Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), CPI Edificio 8E, Avda. Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
Mari-Cruz
MC
Castillo
Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), CPI Edificio 8E, Avda. Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
Jorge
J
Lozano-Juste
Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), CPI Edificio 8E, Avda. Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
Miguel
M
González-Guzmán
Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), CPI Edificio 8E, Avda. Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
Lesia
L
Rodriguez
Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), CPI Edificio 8E, Avda. Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
Pedro L
PL
Rodriguez
Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia), CPI Edificio 8E, Avda. Ingeniero Fausto Elio s/n, 46022 Valencia, Spain. jleon@ibmcp.upv.es.
José
J
León
D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000235:genetics / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D000071636:Protein Phosphatase 2C; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D000040:Abscisic Acid; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C