Righetto Germanna Lima, Sriranganadane Dev, Halabelian Levon, Chiodi Carla G, Elkins Jonathan M, Massirer Katlin B, Gileadi Opher, Menossi Marcelo, Couñago Rafael M
Functional Genome Laboratory, Department of Genetics, Evolution, and Bioagents, Institute of Biology, State University of Campinas, Campinas, Brazil.
Centro de Química Medicinal (CQMED), Centro de Biologia Molecular e Engenharia Genética (CBMEG), Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil.
Front Plant Sci. 2019 Sep 17;10:1105. doi: 10.3389/fpls.2019.01105. eCollection 2019.
Resistance to drought stress is fundamental to plant survival and development. Abscisic acid (ABA) is one of the major hormones involved in different types of abiotic and biotic stress responses. ABA intracellular signaling has been extensively explored in and occurs a phosphorylation cascade mediated by three related protein kinases, denominated SnRK2s (SNF1-related protein kinases). However, the role of ABA signaling and the biochemistry of SnRK2 in crop plants remains underexplored. Considering the importance of the ABA hormone in abiotic stress tolerance, here we investigated the regulatory mechanism of sugarcane SnRK2s-known as stress/ABA-activated protein kinases (SAPKs). The crystal structure of ScSAPK10 revealed the characteristic SnRK2 family architecture, in which the regulatory SnRK2 box interacts with the kinase domain αC helix. To study sugarcane SnRK2 regulation, we produced a series of mutants for the protein regulatory domains SnRK2 box and ABA box. Mutations in ScSAPK8 SnRK2 box aimed at perturbing its interaction with the protein kinase domain reduced protein kinase activity . On the other hand, mutations to ScSAPK ABA box did not impact protein kinase activity but did alter the protein autophosphorylation pattern. Taken together, our results demonstrate that both SnRK2 and ABA boxes might play a role in sugarcane SnRK2 function.
对干旱胁迫的抗性是植物生存和发育的基础。脱落酸（ABA）是参与不同类型非生物和生物胁迫反应的主要激素之一。ABA细胞内信号传导已在多个方面得到广泛研究，并且通过由三种相关蛋白激酶（称为SnRK2s，即SNF1相关蛋白激酶）介导的磷酸化级联反应发生。然而，ABA信号传导的作用以及SnRK2在作物中的生物化学仍未得到充分探索。考虑到ABA激素在非生物胁迫耐受性中的重要性，我们在此研究了甘蔗SnRK2s（称为胁迫/ABA激活蛋白激酶，SAPKs）的调控机制。ScSAPK10的晶体结构揭示了SnRK2家族的特征结构，其中调节性SnRK2结构域与激酶结构域αC螺旋相互作用。为了研究甘蔗SnRK2的调控，我们针对蛋白质调节结构域SnRK2结构域和ABA结构域产生了一系列突变体。ScSAPK8的SnRK2结构域中的突变旨在破坏其与蛋白激酶结构域的相互作用，从而降低了蛋白激酶活性。另一方面，ScSAPK的ABA结构域的突变不会影响蛋白激酶活性，但会改变蛋白的自磷酸化模式。综上所述，我们的结果表明，SnRK2结构域和ABA结构域可能在甘蔗SnRK2的功能中发挥作用。
