Molecular insights into the activation mechanism of the slow anion channel AtSLAH3.

Cryo-EM structures show the L400A mutant of the plant slow anion channel SLAH3 is captured in a dilated, open-like conformation, unlike the auto-inhibited WT channel.

• Why it matters: SLAH3 regulates stomatal closure and stress responses, but its activation mechanism is poorly understood, limiting insight into how nitrate signaling and stress adaptation are controlled.
• What they did: The authors determined cryo-EM structures of WT SLAH3 and gain-of-function pore-lining mutants from a targeted mutagenesis screen, including L400A, and compared conformations.
• The result: Concerted rearrangements of pore-lining transmembrane helices and intracellular regulatory elements support an activation model where displacement of an intracellular auto-inhibitory module relieves pore occlusion and widens the anion-transport entrance.

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