9LB0

Cryo-EM structure of the MK7-bound succinate dehydrogenase from Chloroflexus aurantiacus

9LB0 の概要

• エントリーDOI: 10.2210/pdb9lb0/pdb
• EMDBエントリー: 62934
• 分子名称: Succinate dehydrogenase or fumarate reductase, flavoprotein subunit, MENAQUINONE-7, 4Fe-4S ferredoxin iron-sulfur binding domain protein, ... (10 entities in total)
• 機能のキーワード: succinate: menaquinone oxidoreductase; 3-hydroxypropionate cycle; succinate dehydrogenase;electron transfer, membrane protein
• 由来する生物種: Chloroflexus aurantiacus J-10-fl; 詳細
• タンパク質・核酸の鎖数: 9
• 化学式量合計: 399829.12

構造登録者

Zhang, X.,Wu, J.Y.,Xu, X.L. (登録日: 2025-01-02, 公開日: 2025-11-12, 最終更新日: 2026-03-25)

主引用文献

Zhang, X.,Wu, J.,Wang, J.,He, H.,Liu, A.,Hong, X.,Yu, Y.,Pei, X.,Fang, X.,Xin, Y.,Yu, L.,Tian, C.,Xu, X.
Structural basis of menaquinone reduction by succinate dehydrogenase from Chloroflexus aurantiacus.
Nat Commun, 16:10782-10782, 2025

PubMed Abstract: Succinate: menaquinone oxidoreductase (SQR) couples the oxidation of succinate with the reduction of menaquinone (MK) as part of the TCA cycle and the aerobic respiratory chain in MK-containing bacteria and archaea. Despite its significance, questions persist regarding the electron and proton transfer mechanisms that drive the endergonic MK reduction by succinate. In this study, we determine cryo-EM structures of succinate dehydrogenase (SDH) from Chloroflexus aurantiacus (CaSDH), a facultative filamentous anoxygenic phototroph (FAP) that forms one of the earliest branches of photosynthetic bacteria. The structures of trimeric CaSDH, resolved in both apo- and MK-bound forms, reveal a single membrane-anchoring subunit containing two b-type hemes, a canonical Q site, and a Q site with atypical location, configuration and specificity, each bound to MK molecules. Using structural analysis, EPR, and enzymatic assays, we uncover electron transfer pathways connecting succinate oxidation to MK reduction at the Q and Q sites. These findings provide structural insights into the electron and proton transfer mechanisms of MK-dependent diheme SQRs and establish a foundation for structure-based inhibitor design and antibacterial drug development targeting these enzymes.

PubMed: 41315263
DOI: 10.1038/s41467-025-65828-3

実験手法

ELECTRON MICROSCOPY (2.74 Å)