biostudies-literatureUnknown118(18)Deng YNStomata in leaves regulate gas exchange between the plant and its atmosphere. Various environmental stimuli elicit abscisic acid (ABA); ABA leads to phosphoactivation of slow anion channel 1 (SLAC1); SLAC1 activity reduces turgor pressure in aperture-defining guard cells; and stomatal closure ensues. We used electrophysiology for functional characterizations of Arabidopsis thaliana SLAC1 (AtSLAC1) and cryoelectron microscopy (cryo-EM) for structural analysis of Brachypodium distachyon SLAC1 (BdSLAC1), at 2.97-Å resolution. We identified 14 phosphorylation sites in AtSLAC1 and showed nearly 330-fold channel-activity enhancement with 4 to 6 of these phosphorylated. Seven SLAC1-conserved arginines are poised in BdSLAC1 for regulatory interaction with the N-terminal extension. This BdSLAC1 structure has its pores closed, in a basal state, spring loaded by phenylalanyl residues in high-energy conformations. SLAC1 phosphorylation fine-tunes an equilibrium between basal and activated SLAC1 trimers, thereby controlling the degree of stomatal opening.Proceedings of the National Academy of Sciences of the United States of Americae2015151118https://www.ebi.ac.uk/biostudies/studies/S-EPMC8106318biostudies-literatureStructure and activity of SLAC1 channels for stomatal signaling in leaves.PMC8106318Clarke OBQin LDeng YNWang YCLi FSu MXie QZhen GXHuang XHKashtoh HWang QLi QYHendrickson WAZhang CRTang LHChen YHGao HLfalseStructure and activity of SLAC1 channels for stomatal signaling in leaves.Stomata in leaves regulate gas exchange between the plant and its atmosphere. Various environmental stimuli elicit abscisic acid (ABA); ABA leads to phosphoactivation of slow anion channel 1 (SLAC1); SLAC1 activity reduces turgor pressure in aperture-defining guard cells; and stomatal closure ensues. We used electrophysiology for functional characterizations of Arabidopsis thaliana SLAC1 (AtSLAC1) and cryoelectron microscopy (cryo-EM) for structural analysis of Brachypodium distachyon SLAC1 (BdSLAC1), at 2.97-Å resolution. We identified 14 phosphorylation sites in AtSLAC1 and showed nearly 330-fold channel-activity enhancement with 4 to 6 of these phosphorylated. Seven SLAC1-conserved arginines are poised in BdSLAC1 for regulatory interaction with the N-terminal extension. This BdSLAC1 structure has its pores closed, in a basal state, spring loaded by phenylalanyl residues in high-energy conformations. SLAC1 phosphorylation fine-tunes an equilibrium between basal and activated SLAC1 trimers, thereby controlling the degree of stomatal opening.2021-01-01T00:00:00Z2021 May2025-04-04T11:00:44.437Z2025-04-04T11:00:44.437ZS-EPMC81063183392696310.1073/pnas.2015151118