Stomata, microscopic pores on plant leaves, regulate gas exchange and water loss by opening or closing in response to environmental cues. Guard cells surrounding each stoma regulate this process by altering their turgor pressure through ion transport, with ionic potassium being the predominant osmotic solute.
In Arabidopsis, the outward-rectifying potassium channel GORK drives potassium efflux during stomatal closure. Its bioengineering has demonstrated the potential for enhanced carbon assimilation and water use efficiency.
In a study published in Nature Communications, researchers from the Center for Excellence in Molecular Plant Sciences of the Chinese Academy of Sciences and the University of Glasgow combined structural and functional analyses to reveal the structural basis and unique gating mechanism of Arabidopsis potassium channel GORK.
Researchers first resolved high-resolution structures of the GORK channel in closed and pre-open states using cryo-EM. They found that the GORK channel forms a homotetramer with transmembrane pore (PD) and voltage-sensor (VSD) domains, and cytosolic C-linker, cyclic nucleotide-binding homology domain (CNBHD), and ankyrin repeats (ANK) domain.
Then, researchers found that the interactions center around two coupling sites that functional analysis established are critical for channel gating. The mutations at Coupling Site I reduced activation energy barriers, accelerated activation, and delayed deactivation, while truncations at Coupling Site II destabilized interactions between the N-terminus and CNBHD, favoring pre-open states.
Notably, the channel was also subject to putative, ligand-like interactions within the CNBHD, rendering its gating independent of cyclic nucleotides such as cAMP or cGMP.
These findings demonstrate a multi-step mechanism of semi-independent conformational transitions that underlie channel activity. This study offers promising new sites for optimizing GORK to engineer stomata.
More information:
Xue Zhang et al, GORK K+ channel structure and gating vital to informing stomatal engineering, Nature Communications (2025). DOI: 10.1038/s41467-025-57287-7
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Chinese Academy of Sciences
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Detailed analysis of GORK channel offers insights into plant water regulation (2025, February 27)
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