Mechanistic insights into phosphoactivation of SLAC1 in guard cell signaling

• 成果类型: Article
• 署名作者: Qin, Li; Deng, Ya-nan; Zhang, Xiang-yun; Tang, Ling-hui; Zhang, Chun - rui; Xu, Shi-min; Wang, Ke; Wang, Mei- hua; Zhang, Xian - hui; Su, Min; Xie, Qi; Hendrickson, Wayne A.; Chen, Yu-hang
• 署名单位: Chinese Academy of Sciences; Institute of Genetics & Developmental Biology, CAS; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Chinese Academy of Sciences; Institute of Genetics & Developmental Biology, CAS; Columbia University; Columbia University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10236
• DOI: 10.1073/pnas.2323040121
• 发表日期: 2024-07-16
• 关键词: anion channel slac1; abscisic-acid; ion channels; stomata; transduction; activation; regulators; kinases; nitrate; abi1

摘要

Stomata in leaves regulate gas (carbon dioxide and water vapor) exchange and water transpiration between plants and the atmosphere. SLow Anion Channel 1 (SLAC1) mediates anion efflux from guard cells and plays a crucial role in controlling stomatal aperture. It serves as a central hub for multiple signaling pathways in response to environmental stimuli, with its activity regulated through phosphorylation via various plant protein kinases. However, the molecular mechanism underlying SLAC1 phosphoactivation has remained elusive. Through a combination of protein sequence analyses, AlphaFold- based- based modeling and electrophysiological studies, we unveiled that the highly conserved motifs on the N-- and C-- terminal segments of SLAC1 form a cytosolic regulatory domain (CRD) that interacts with the transmembrane domain(TMD), thereby maintaining the channel in an autoinhibited state. Mutations in these conserved motifs destabilize the CRD, releasing autoinhibition in SLAC1 and enabling its transition into an activated state. Our further studies demonstrated that SLAC1 activation undergoes an autoinhibition-- release process and subsequent structural changes in the pore helices. These findings provide mechanistic insights into the activation mechanism of SLAC1 and shed light on understanding how SLAC1 controls stomatal closure in response to environmental stimuli.