Structural basis of menaquinone reduction by succinate dehydrogenase from Chloroflexus aurantiacus.

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_P site, and a Q

SUBMITTER: Zhang X 

PROVIDER: S-EPMC12663545 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature