Brassinosteroid-regulated GSK3/Shaggy-like Kinases Phosphorylate Mitogen-activated Protein (MAP) Kinase Kinases, Which Control Stomata Development in Arabidopsis thaliana
Résumé
Brassinosteroids (BRs) are steroid hormones that coordinate fundamental developmental programs in plants. In this study we show that in addition to the well established roles of BRs in regulating cell elongation and cell division events, BRs also govern cell fate decisions during stomata development in Arabidopsis thaliana. In wild-type A. thaliana, stomatal distribution follows the one-cell spacing rule; that is, adjacent stomata are spaced by at least one intervening pavement cell. This rule is interrupted in BR-deficient and BR signaling-deficient A. thaliana mutants, resulting in clustered stomata. We demonstrate that BIN2 and its homologues, GSK3/Shaggy-like kinases involved in BR signaling, can phosphorylate the MAPK kinases MKK4 and MKK5, which are members of the MAPK module YODA-MKK4/5-MPK3/6 that controls stomata development and patterning. BIN2 phosphorylates a GSK3/Shaggy-like kinase recognition motif in MKK4, which reduces MKK4 activity against its substrate MPK6 in vitro. In vivo we show that MKK4andMKK5act downstream of BR signaling because their overexpression rescued stomata patterning defects in BR-deficient plants. A model is proposed in which GSK3-mediated phosphorylation of MKK4 and MKK5 enables for a dynamic integration of endogenous or environmental cues signaled by BRs into cell fate decisions governed by the YODA-MKK4/5-MPK3/6 module.
Mots clés
Arabidopsis thaliana
Brassinosteroids
Cell divisions
Cell fate decision
Environmental cues
Mitogen activated protein kinase
Over-expression
Cell proliferation
Cells
Cytology
Plants (botany)
Steroid hormones
Enzymes
Arabidopsis protein
BIN2 protein
brassinosteroid
mitogen activated protein kinase 3
mitogen activated protein kinase 6
mitogen activated protein kinase kinase 4
mitogen activated protein kinase kinase 5
unclassified drug
Arabidopsis
article
cell division
cell elongation
cell fate
controlled study
enzyme activity
enzyme phosphorylation
enzyme repression
hormone action
in vitro study
in vivo study
nonhuman
plant development
plant stoma
priority journal
protein expression
protein function
protein protein interaction
wild type
Cloning
Molecular
Escherichia coli
Gene Expression Regulation
Enzymologic
Plant
Glutathione Transferase
Glycogen Synthase Kinase 3
Mitogen-Activated Protein Kinase Kinases
Models
Biological
Genetic
Phosphorylation
Plant Stomata
Plants
Genetically Modified
Recombinant Proteins
Signal Transduction
Steroids