title: The structure of the C-terminal domain of the protein kinase AtSOS2 bound to the calcium sensor AtSOS3.
abstract: The plant SOS2 family of protein kinases and their interacting activators, the SOS3 family of calcium-binding proteins, function together in decoding calcium signals elicited by different environmental stimuli. SOS2 is activated by Ca-SOS3 and subsequently phosphorylates the ion transporter SOS1 to bring about cellular ion homeostasis under salt stress. In addition to possessing the kinase activity, members of the SOS2 family of protein kinases can bind to protein phosphatase 2Cs. The crystal structure of the binary complex of Ca-SOS3 with the C-terminal regulatory moiety of SOS2 resolves central questions regarding the dual function of SOS2 as a kinase and a phosphatase-binding protein. A comparison with the structure of unbound SOS3 reveals the basis of the molecular function of this family of kinases and their interacting calcium sensors. Furthermore, our study suggests that the structure of the phosphatase-interaction domain of SOS2 defines a scaffold module conserved from yeast to human.
authors.affiliation: Grupo de Cristalografía Macromolecular y Biología Estructural, Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Serrano 119, Madrid E-28006, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Sánchez-Barrena
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Fujii
authors.forename: Ivan
authors.initials: I
authors.lastname: Angulo
authors.forename: Martín
authors.initials: M
authors.lastname: Martínez-Ripoll
authors.forename: Jian-Kang
authors.initials: JK
authors.lastname: Zhu
authors.forename: Armando
authors.initials: A
authors.lastname: Albert
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D003460:Crystallization; D004789:Enzyme Activation; D006706:Homeostasis / Q000502:physiology; D052139:Intracellular Calcium-Sensing Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D000071636:Protein Phosphatase 2C; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism*; D012492:Salts / Q000737:chemistry
chemical_list: D029681:Arabidopsis Proteins; D052139:Intracellular Calcium-Sensing Proteins; C112941:SOS3 protein, Arabidopsis; D012492:Salts; C406738:SOS2 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C; D002118:Calcium