Structure reveals a regulation mechanism of plant outward-rectifying K+ channel CORK by structural rearrangements in the CNBD-Ankyrin bridge

• 成果类型: Article
• 署名作者: Yamanashi, Taro; Muraoka, Yuki; Furuta, Tadaomi; Kume, Tsukasa; Sekido, Natsuko; Saito, Shunya; Terashima, Shota; Yokoyama, Takeshi; Tanaka, Yoshikazu; Miyamoto, Atsushi; Sato, Kanane; Ito, Tomoyuki; Nakazawa, Hikaru; Umetsu, Mitsuo; Tanudjaja, Ellen; Tsujii, Masaru; Dreyer, Ingo; Schroeder, Julian I.; Ishimaru, Yasuhiro; Uozumi, Nobuyuki
• 署名单位: Tohoku University; Tohoku University; Universidad de Talca; University of California System; University of California San Diego
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8451
• DOI: 10.1073/pnas.2500070122
• 发表日期: 2025-07-23
• 关键词: potassium channel; guard-cells; arabidopsis-thaliana; plasma-membrane; abscisic-acid; rectifier; transport; gork; expression; integration

摘要

Guard cells, which regulate stomatal apertures in plants, possess a sophisticated mechanism for regulating turgor pressure. The outward- rectifying K+out channel GORK, expressed in guard cells of the plant Arabidopsis thaliana, is a central component that promotes stomatal closure by releasing K+ to the extracellular space, thereby lowering turgor pressure. To date, the structural basis underlying the regulation of the K+ transport activity of GORK is unclear. Using cryo- EM, we determined the structures of the GORK outward- rectifying K+ channel with a resolution of 3.16 to 3.27 & Aring; in five distinct conformations that differ significantly in their C- terminal cyclic nucleotide binding domain (CNBD) and ankyrin repeat (ANK) domain. The C- linker connects bridge, and ANK. The structural changes and interactions in the C- linker determine whether the closed state of GORK is closer to the preopen state or in a more removed state from the open state of the channel. In particular, interconversion in the short sequence within the CNBD-Ankyrin bridge plays a decisive role in this determination. This region forms an alpha- helix in the preopened state, while it adopts a nonhelical structure in further distant closed states. The dynamics of the cytosolic region strongly during stomatal closure.