title: The structure of Arabidopsis thaliana OST1 provides insights into the kinase regulation mechanism in response to osmotic stress.
abstract: SnRK [SNF1 (sucrose non-fermenting-1)-related protein kinase] 2.6 [open stomata 1 (OST1)] is well characterized at molecular and physiological levels to control stomata closure in response to water-deficit stress. OST1 is a member of a family of 10 protein kinases from Arabidopsis thaliana (SnRK2) that integrates abscisic acid (ABA)-dependent and ABA-independent signals to coordinate the cell response to osmotic stress. A subgroup of protein phosphatases type 2C binds OST1 and keeps the kinase dephosphorylated and inactive. Activation of OST1 relies on the ABA-dependent inhibition of the protein phosphatases type 2C and the subsequent self-phosphorylation of the kinase. The OST1 ABA-independent activation depends on a short sequence motif that is conserved among all the members of the SnRK2 family. However, little is known about the molecular mechanism underlying this regulation. The crystallographic structure of OST1 shows that ABA-independent regulation motif stabilizes the conformation of the kinase catalytically essential α C helix, and it provides the basis of the ABA-independent regulation mechanism for the SnRK2 family of protein kinases.
authors: Departamento de Cristalografía y Biología Estructural, Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Serrano 119, Madrid E-28006, Spain.
authors: Cristina
authors: C
authors: Yunta
authors: Martín
authors: M
authors: Martínez-Ripoll
authors: Jian-Kang
authors: JK
authors: Zhu
authors: Armando
authors: A
authors: Albert
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D018506:Gene Expression Regulation, Plant; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009995:Osmosis; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000071636:Protein Phosphatase 2C; D015398:Signal Transduction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014461:Ultracentrifugation
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C