Departamento de Cristalografía y Biología Estructural, Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, Serrano 119, Madrid E-28006, Spain.
J Mol Biol. 2011 Nov 18;414(1):135-44. doi: 10.1016/j.jmb.2011.09.041. Epub 2011 Oct 1.
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.
SnRK[蔗糖非发酵-1（SNF1）相关蛋白激酶]2.6[开放气孔 1（OST1）]在分子和生理水平上得到了很好的描述，以控制气孔对水分胁迫的关闭。OST1 是拟南芥（SnRK2）10 种蛋白激酶家族的成员之一，它整合了依赖 ABA 和不依赖 ABA 的信号，以协调细胞对渗透胁迫的反应。一组蛋白磷酸酶 2C 型结合 OST1，使激酶去磷酸化并失活。OST1 的激活依赖于 ABA 依赖性抑制蛋白磷酸酶 2C，以及随后激酶的自我磷酸化。OST1 不依赖 ABA 的激活依赖于一个在所有 SnRK2 家族成员中保守的短序列基序。然而，对于这种调节的分子机制知之甚少。OST1 的晶体结构表明，不依赖 ABA 的调节基序稳定了激酶催化必需的αC 螺旋的构象，为 SnRK2 家族蛋白激酶的不依赖 ABA 的调节机制提供了基础。
