Structural insight on the mechanism of an electron-bifurcating [FeFe] hydrogenase

13 September 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Electron-bifurcation is a fundamental energy conservation mechanism in nature. The electron-bifurcating [FeFe] hydrogenase from Thermotoga maritima (HydABC) requires both NADH and ferredoxin to reduce protons generating hydrogen. The mechanism of electron-bifurcation in HydABC remains enigmatic primarily due to the lack of structural information. Here, we present a 2.3 Å electron cryo-microscopy structure of HydABC. The structure is a heterododecamer composed of two independent ‘halves’ each made of two strongly interacting HydABC trimers electrically connected via a [4Fe-4S] cluster, forming a bus-bar system. Symmetry expansion identified two conformations: a “closed bridge” and an “open bridge” conformation, where a Zn2+ site may act as a “hinge” allowing domain movement. Based on these structural revelations, we propose two new mechanisms of electron-bifurcation in HydABC.

Keywords

catalysis
electron bifurcation
hydrogenase
flavin
electron cryo-microscopy
structure
mechanism
energy conservation

Supplementary materials

Title
Description
Actions
Title
Furlan 2021 HydABC Supplementary Materials
Description
Materials and methods Supplementary text Figs. S1 to S8 Table S1
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.