8J5D

Cryo-EM structure of starch degradation complex of BAM1-LSF1-MDH

8J5D の概要

• エントリーDOI: 10.2210/pdb8j5d/pdb
• EMDBエントリー: 35985
• 分子名称: Beta-amylase 1, chloroplastic, Malate dehydrogenase, chloroplastic, Phosphoglucan phosphatase LSF1, chloroplastic (3 entities in total)
• 機能のキーワード: amylase, starch degradation, hydrolase
• 由来する生物種: Arabidopsis thaliana (thale cress); 詳細
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 183583.46

構造登録者

Guan, Z.Y.,Liu, J.,Yan, J.J. (登録日: 2023-04-21, 公開日: 2024-01-10, 最終更新日: 2025-07-23)

主引用文献

Liu, J.,Wang, X.,Guan, Z.,Wu, M.,Wang, X.,Fan, R.,Zhang, F.,Yan, J.,Liu, Y.,Zhang, D.,Yin, P.,Yan, J.
The LIKE SEX FOUR 1-malate dehydrogenase complex functions as a scaffold to recruit beta-amylase to promote starch degradation.
Plant Cell, 36:194-212, 2023

PubMed Abstract: In plant leaves, starch is composed of glucan polymers that accumulate in chloroplasts as the products of photosynthesis during the day; starch is mobilized at night to continuously provide sugars to sustain plant growth and development. Efficient starch degradation requires the involvement of several enzymes, including β-amylase and glucan phosphatase. However, how these enzymes cooperate remains largely unclear. Here, we show that the glucan phosphatase LIKE SEX FOUR 1 (LSF1) interacts with plastid NAD-dependent malate dehydrogenase (MDH) to recruit β-amylase (BAM1), thus reconstituting the BAM1-LSF1-MDH complex. The starch hydrolysis activity of BAM1 drastically increased in the presence of LSF1-MDH in vitro. We determined the structure of the BAM1-LSF1-MDH complex by a combination of cryo-electron microscopy, crosslinking mass spectrometry, and molecular docking. The starch-binding domain of the dual-specificity phosphatase and carbohydrate-binding module of LSF1 was docked in proximity to BAM1, thus facilitating BAM1 access to and hydrolysis of the polyglucans of starch, thus revealing the molecular mechanism by which the LSF1-MDH complex improves the starch degradation activity of BAM1. Moreover, LSF1 is phosphatase inactive, and the enzymatic activity of MDH was dispensable for starch degradation, suggesting nonenzymatic scaffold functions for LSF1-MDH in starch degradation. These findings provide important insights into the precise regulation of starch degradation.

PubMed: 37804098
DOI: 10.1093/plcell/koad259

実験手法

ELECTRON MICROSCOPY (3 Å)