9JF8

Cryo-EM structure of the EXS domain of Arabidopsis thaliana phosphate transporter PHO1;H1

9JF8 の概要

• エントリーDOI: 10.2210/pdb9jf8/pdb
• EMDBエントリー: 61430
• 分子名称: Phosphate transporter PHO1 homolog 1, PHOSPHATE ION (2 entities in total)
• 機能のキーワード: phosphate transport, spx domain, pho1, spx-exs, cryo-em, insp6, membrane protein
• 由来する生物種: Arabidopsis thaliana (Mouse-ear cress)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 90925.09

構造登録者

Fang, S.,Zhang, X.,Zhang, P. (登録日: 2024-09-04, 公開日: 2025-01-22, 最終更新日: 2025-03-05)

主引用文献

Fang, S.,Yang, Y.,Zhang, X.,Yang, Z.,Zhang, M.,Zhao, Y.,Zhang, C.,Yu, F.,Wang, Y.F.,Zhang, P.
Structural mechanism underlying PHO1;H1-mediated phosphate transport in Arabidopsis.
Nat.Plants, 11:309-320, 2025

PubMed Abstract: Arabidopsis PHOSPHATE 1 (AtPHO1) and its closest homologue AtPHO1;H1 are phosphate transporters that load phosphate into the xylem vessel for root-to-shoot translocation. AtPHO1 and AtPHO1;H1 are prototypical members of the unique SPX-EXS family, whose structural and molecular mechanisms remain elusive. In this study, we determined the cryogenic electron microscopy structure of AtPHO1;H1 binding with inorganic phosphate (Pi) and inositol hexakisphosphate in a closed conformation. Further molecular dynamic simulation and AlphaFold prediction support an open conformation. AtPHO1;H1 forms a domain-swapped homodimer that involves both the transmembrane ERD1/XPR1/SYG1 (EXS) domain and the cytoplasmic SYG1/Pho81/XPR1 (SPX) domain. The EXS domain presented by the SPX-EXS family represents a novel protein fold, and an independent substrate transport pathway and substrate-binding site are present in each EXS domain. Two gating residues, Trp719 and Tyr610, are identified above the substrate-binding site to control opening and closing of the pathway. The SPX domain features positively charged patches and/or residues at the dimer interface to accommodate inositol hexakisphosphate molecules, whose binding mediates dimerization and enhances AtPHO1;H1 activity. In addition, a C-terminal tail is required for AtPHO1;H1 activity. On the basis of structural and functional analysis, a working model for Pi efflux mediated by AtPHO1;H1 and its homologues was postulated, suggesting a channel-like mechanism. This study not only reveals the molecular and regulatory mechanism underlying Pi transport mediated by the unique SPX-EXS family, but also provides potential for crop engineering to enhance phosphorus-use efficiency in sustainable agriculture.

PubMed: 39838070
DOI: 10.1038/s41477-024-01895-6

実験手法

ELECTRON MICROSCOPY (3.05 Å)