7T2R

Structure of electron bifurcating Ni-Fe hydrogenase complex HydABCSL in FMN-free apo state

Summary for 7T2R

• Entry DOI: 10.2210/pdb7t2r/pdb
• EMDB information: 25633
• Descriptor: NiFe hydrogenase subunit A, NiFe hydrogenase subunit B, NiFe hydrogenase subunit C, ... (9 entities in total)
• Functional Keywords: hydrogenase complex, electron bifurcation, oxidoreductase
• Biological source: Acetomicrobium mobile; More
• Total number of polymer chains: 10
• Total formula weight: 471861.12

Authors

Feng, X.,Li, H. (deposition date: 2021-12-06, release date: 2022-03-16, Last modification date: 2024-11-06)

Primary citation

Feng, X.,Schut, G.J.,Haja, D.K.,Adams, M.W.W.,Li, H.
Structure and electron transfer pathways of an electron-bifurcating NiFe-hydrogenase.
Sci Adv, 8:eabm7546-eabm7546, 2022

PubMed Abstract: Electron bifurcation enables thermodynamically unfavorable biochemical reactions. Four groups of bifurcating flavoenzyme are known and three use FAD to bifurcate. FeFe-HydABC hydrogenase represents the fourth group, but its bifurcation site is unknown. We report cryo-EM structures of the related NiFe-HydABCSL hydrogenase that reversibly oxidizes H and couples endergonic reduction of ferredoxin with exergonic reduction of NAD. FMN surrounded by a unique arrangement of iron sulfur clusters forms the bifurcating center. NAD binds to FMN in HydB, and electrons from H via HydA to a HydB [4Fe-4S] cluster enable the FMN to reduce NAD. Low-potential electron transfer from FMN to the HydC [2Fe-2S] cluster and subsequent reduction of a uniquely penta-coordinated HydB [2Fe-2S] cluster require conformational changes, leading to ferredoxin binding and reduction by a [4Fe-4S] cluster in HydB. This work clarifies the electron transfer pathways for a large group of hydrogenases underlying many essential functions in anaerobic microorganisms.

PubMed: 35213221
DOI: 10.1126/sciadv.abm7546

Experimental method

ELECTRON MICROSCOPY (3.2 Å)