2025-05-16 中国科学院(CAS)
<関連情報>
- https://english.cas.cn/newsroom/research_news/life/202505/t20250512_1043447.shtml
- https://www.cell.com/cell/fulltext/S0092-8674(25)00463-5
シロイヌナズナAUX1を介したオーキシン流入の構造的洞察 Structural insights into auxin influx mediated by the Arabidopsis AUX1
Zhisen Yang ∙ Hong Wei ∙ Yulin Gan ∙ … ∙ Shutang Tan ∙ Xin Liu ∙ Linfeng Sun
Cell Published:May 15, 2025
DOI:https://doi.org/10.1016/j.cell.2025.04.028
Graphical abstract
Highlights
- AUX1 functions as a proton-coupled, high-affinity auxin importer
- Structure of auxin-bound AUX1 provides insights into auxin-binding mechanism
- Structure of an inhibitor-bound AUX1 is determined
- A histidine residue of AUX1 is identified as a key player in proton coupling
Summary
Auxin is crucial in orchestrating diverse aspects of plant growth and development and modulating responses to environmental signals. The asymmetric spatiotemporal distribution of auxin generates local gradient patterns, which are regulated by both cellular auxin influx and efflux. The AUXIN1/LIKE-AUX1 (AUX1/LAX) family transporters have been identified as major auxin influx carriers. Here, we characterize the auxin uptake mediated by AUX1 from Arabidopsis thaliana. Using cryoelectron microscopy (cryo-EM), we determine its structure in three states: the auxin-unbound, the auxin-bound, and the competitive inhibitor, 3-chloro-4-hydroxyphenylacetic acid (CHPAA)-bound state. All structures adopt an inward-facing conformation. In the auxin-bound structure, indole-3-acetic acid (IAA) is coordinated to AUX1 primarily through hydrogen bonds with its carboxyl group. The functional roles of key residues in IAA binding are validated by in vitro and in planta analyses. CHPAA binds to the same site as IAA. These findings advance our understanding of auxin transport in plants.
