Structural basis of auxin binding and transport by Arabidopsis thaliana AUX1

• 成果类型: Article
• 署名作者: Jing, Dan; Kong, Fang; Lu, Xiaoli; Huang, Gaoxingyu; Huang, Jing; Wang, Haolin; Shi, Yigong; Wang, Chengcheng
• 署名单位: Zhejiang University; Westlake University; Westlake Laboratory; Tsinghua University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8704
• DOI: 10.1073/pnas.2513424122
• 发表日期: 2025-08-05
• 关键词: root gravitropism; influx; define; FAMILY; gene; gui

摘要

Indole-3-acetic acid (IAA), the major form of auxin, is essential for plant growth. Auxin resistant 1 (AUX1), the first identified auxin importer, plays a crucial role in polar auxin transport (PAT). Here, we present cryo-EM structures ofArabidopsis thaliana AUX1 in the IAA-free and IAA-bound states. AUX1 exists as a monomer that contains 11 trans-membrane helices (TMs). TMs 1 to 5 and 6 to 10 constitute the two halves of a classic LeuT-fold, and TM11 interacts with both halves at the interface. In the IAA-bound state, IAA is specifically recognized in a central pocket formed by TM1, TM3, TM6, and TM8. In the presence of IAA, TM1 and TM6 undergo marked conformational changes that are critical for IAA transport. His249 stands out to be a key residue for substrate uptake and release. Our structures reveal the molecular basis for AUX1-mediated IAA binding and transport.