Structural insights into AtABCG25,an angiosperm-specific abscisic acid exporter  

作　　者：Jian Xin Yeling Zhou Yichun Qiu He Geng Yuzhu Wang Yi Song Jiansheng Liang Kaige Yan 

机构地区：[1]Department of Chemical Biology,School of Life Sciences,Southern University of Science and Technology,Shenzhen 518055,China [2]Institute of Plant and Food Science,Department of Biology,School of Life Sciences,Southern University of Science and Technology,Shenzhen 518055,China [3]Max Planck Institute of Molecular Plant Physiology,Potsdam-Golm,Germany [4]Institute for Biological Electron Microscopy,Southern University of Science and Technology,Shenzhen,Guangdong,China

出　　处：《Plant Communications》2024年第1期284-295,共12页植物通讯（英文）

基　　金：supported by the National Natural Science Foundation of China (grant 32271251 to K.Y.,grant 32070292 to J.L.);the Guangdong Innovative and Entrepreneurial Research Team Program (grants 2021Z T09Y104 and 2021QN02Y429 to K.Y.);the Shenzhen Science and Technology Program (grants JCYJ20220530115214033 and KQTD20210811090115021 to K.Y.,grants JCYJ20170817104523456 and KQTD20190929173906742 to J.L.);Scientific research funding for postdoctoral researchers staying at Shenzhen (grant K20227507 to Y.Z.);supported by the Stable Support Plan Program of the Shenzhen Natural Science Fund (grant 20220815160107001).

摘　　要：Cellular hormone homeostasis is essential for precise spatial and temporal signaling responses and plantfitness.Abscisic acid(ABA)plays pivotal roles in orchestrating various developmental and stress re-sponses and confersfitness benefits over ecological and evolutionary timescales in terrestrial plants.Cellular ABA level is regulated by complex processes,including biosynthesis,catabolism,and transport.AtABCG25 is thefirst ABA exporter identified through genetic screening and affects diverse ABA responses.Resolving the structural basis of ABA export by ABCG25 is critical for further manipulations of ABA homeostasis and plantfitness.We used cryo-electron microscopy to elucidate the structural dynamics of AtABCG25 and successfully characterized different states,including apo AtABCG25,ABA-bound AtABCG25,and ATP-bound AtABCG25(E232Q).Notably,AtABCG25 forms a homodimer that fea-tures a deep,slit-like cavity in the transmembrane domain,and we precisely characterized the critical residues in the cavity where ABA binds.ATP binding triggers closure of the nucleotide-binding domains and conformational transitions in the transmembrane domains.We show that AtABCG25 belongs to a conserved ABCG subfamily that originated during the evolution of angiosperms.This subfamily neofunctionalized to regulate seed germination via the endosperm,in concert with the evolution of this angio-sperm-specific,embryo-nourishing tissue.Collectively,thesefindings provide valuable insights into the intricate substrate recognition and transport mechanisms of the ABA exporter AtABCG25,paving the way for genetic manipulation of ABA homeostasis and plantfitness.

关 键 词：AtABCG25 abscisic acid ABC transporters CRYO-EM STRUCTURE 

分 类 号：Q94[生物学—植物学]