Department of Neurology, the First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, CAS Centre for Excellence in Molecular Cell Science, Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China.
Institute on Aging and Brain Disorders, the First Affiliated Hospital of USTC, CAS Key Laboratory of Innate Immunity and Chronic Disease, University of Science and Technology of China, Hefei, 230027, China.
Nat Commun. 2022 May 6;13(1):2511. doi: 10.1038/s41467-022-30253-3.
Stomata play a critical role in the regulation of gas exchange and photosynthesis in plants. Stomatal closure participates in multiple stress responses, and is regulated by a complex network including abscisic acid (ABA) signaling and ion-flux-induced turgor changes. The slow-type anion channel SLAC1 has been identified to be a central controller of stomatal closure and phosphoactivated by several kinases. Here, we report the structure of SLAC1 in Arabidopsis thaliana (AtSLAC1) in an inactivated, closed state. The cytosolic amino (N)-terminus and carboxyl (C)-terminus of AtSLAC1 are partially resolved and form a plug-like structure which packs against the transmembrane domain (TMD). Breaking the interactions between the cytosolic plug and transmembrane domain triggers channel activation. An inhibition-release model is proposed for SLAC1 activation by phosphorylation that the cytosolic plug dissociates from the transmembrane domain upon phosphorylation, and induces conformational changes to open the pore. These findings facilitate our understanding of the regulation of SLAC1 activity and stomatal aperture in plants.
气孔在植物的气体交换和光合作用调节中起着关键作用。气孔关闭参与多种胁迫反应，并受包括脱落酸（ABA）信号和离子流诱导的膨压变化在内的复杂网络调控。慢型阴离子通道 SLAC1 已被确定为气孔关闭的中央控制器，并被多种激酶磷酸化激活。在这里，我们报告了拟南芥 SLAC1（AtSLAC1）在失活、关闭状态下的结构。AtSLAC1 的细胞质氨基（N）末端和羧基（C）末端部分解析，并形成一个塞状结构，与跨膜域（TMD）相对。打破细胞质塞与跨膜域之间的相互作用会触发通道激活。提出了一种 SLAC1 磷酸化激活的抑制-释放模型，即细胞质塞在磷酸化后与跨膜域解离，并诱导构象变化以打开孔。这些发现有助于我们理解 SLAC1 活性和植物气孔开度的调节。
