9VRE

Cryo-EM structure of rice multidrug resistance protein 5 (MRP5) with InsP6 in state B

9VRE の概要

• エントリーDOI: 10.2210/pdb9vre/pdb
• EMDBエントリー: 65285
• 分子名称: ABC transporter C family member 13, INOSITOL HEXAKISPHOSPHATE (2 entities in total)
• 機能のキーワード: abc-type transporter, monomer, transport protein
• 由来する生物種: Oryza sativa Japonica Group (Japanese rice)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 166981.94

構造登録者

Zou, J.,Zhang, J.,Liu, Z. (登録日: 2025-07-06, 公開日: 2026-04-01)

主引用文献

Zuo, J.,Zhang, J.,Tang, Y.,Jiang, L.,Cao, S.,Liu, Y.,Shen, C.,Wang, C.,Chen, H.,Xiong, L.,Yin, P.,Gong, Z.,Liu, Z.
Cryo-EM structures of Oryza sativa MRP5 reveal a phytate accumulation mechanism in plant vacuoles.
Plant Cell, 2026

PubMed Abstract: Phytate (phytic acid, or InsP6), the primary phosphorus storage compound in plants, plays essential roles in nutrient homeostasis and cellular signaling. However, its strong metal-chelating properties make cytosolic accumulation cytotoxic, necessitating its sequestration into vacuoles for safe storage. Here, we present the cryo-EM structures of the rice vacuolar phytate transporter, OsMRP5, captured in distinct functional states. These structures reveal the molecular basis of OsMRP5 function as an ATP-binding cassette (ABC) transporter. OsMRP5 employs a specialized substrate-recognition mechanism, uniquely adapted to bind the fully hydrophilic InsP6 through extensive electrostatic and hydrogen-bonding interactions within two distinct, highly polar binding sites in its central cavity. A distinctive electropositive tunnel, positioned above the central cavity, forms a continuous pathway connecting the InsP6-binding pocket to the vacuolar export site. This tunnel likely generates an electrostatic attraction that facilitates the movement of the highly anionic InsP6 through the transporter. By mapping mutations from low-phytic acid (lpa) crop variants onto the OsMRP5 structures, we pinpoint their conserved locations critical for transporter function and validate their impact experimentally. These results reveal how OsMRP5 recognizes and transports the highly charged InsP6 molecule into vacuoles, providing a molecular framework for targeted manipulation of this agriculturally important transporter.

PubMed: 41875395
DOI: 10.1093/plcell/koag088

実験手法

ELECTRON MICROSCOPY (3.5 Å)