The structure of arabidopsis thaliana OST1 provides insights into the kinase regulation mechanism in response to osmotic stress
KAUST DepartmentCenter for Desert Agriculture
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AbstractSnRK [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. © 2011 Elsevier Ltd. All rights reserved.
SponsorsWe thank Dr. Laura Lagartera for the analytical ultracentrifugation data analysis, Dr. F. J. Quintero for the access to his laboratory and advice in the kinase activity measurements and Dr. John Klingler for critical reading of the manuscript. A.A. thanks the European Synchrotron Radiation Facility for the access to the synchrotron radiation source. This work was funded by the grant BFU2008-00368/BMC, BFU2001-25384 and "Factoria de Cristalizacion" Consolider-Ingenio 2010 of the Spanish "Plan Nacional" (Ministerio de Ciencia e Innovacion) to A.A.
JournalJournal of Molecular Biology
PubMed Central IDPMC3593245
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