EMD-7468
cryoEM structure of a respiratory membrane-bound hydrogenase
EMD-7468
Single-particle3.7 Å
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Map released: 23/05/2018
Last modified: 13/03/2024
Sample Organism:
Pyrococcus furiosus COM1,
Pyrococcus furiosus (strain ATCC 43587 / DSM 3638 / JCM 8422 / Vc1),
Pyrococcus furiosus
Sample: Membrane-bound Hydrogenase (MBH) complex
Fitted models: 6cfw (Avg. Q-score: 0.499)
Deposition Authors: Li HL, Yu HJ
Sample: Membrane-bound Hydrogenase (MBH) complex
Fitted models: 6cfw (Avg. Q-score: 0.499)
Deposition Authors: Li HL, Yu HJ
Structure of an Ancient Respiratory System.
Abstract:
Hydrogen gas-evolving membrane-bound hydrogenase (MBH) and quinone-reducing complex I are homologous respiratory complexes with a common ancestor, but a structural basis for their evolutionary relationship is lacking. Here, we report the cryo-EM structure of a 14-subunit MBH from the hyperthermophile Pyrococcus furiosus. MBH contains a membrane-anchored hydrogenase module that is highly similar structurally to the quinone-binding Q-module of complex I while its membrane-embedded ion-translocation module can be divided into a H+- and a Na+-translocating unit. The H+-translocating unit is rotated 180° in-membrane with respect to its counterpart in complex I, leading to distinctive architectures for the two respiratory systems despite their largely conserved proton-pumping mechanisms. The Na+-translocating unit, absent in complex I, resembles that found in the Mrp H+/Na+ antiporter and enables hydrogen gas evolution by MBH to establish a Na+ gradient for ATP synthesis near 100°C. MBH also provides insights into Mrp structure and evolution of MBH-based respiratory enzymes.
Hydrogen gas-evolving membrane-bound hydrogenase (MBH) and quinone-reducing complex I are homologous respiratory complexes with a common ancestor, but a structural basis for their evolutionary relationship is lacking. Here, we report the cryo-EM structure of a 14-subunit MBH from the hyperthermophile Pyrococcus furiosus. MBH contains a membrane-anchored hydrogenase module that is highly similar structurally to the quinone-binding Q-module of complex I while its membrane-embedded ion-translocation module can be divided into a H+- and a Na+-translocating unit. The H+-translocating unit is rotated 180° in-membrane with respect to its counterpart in complex I, leading to distinctive architectures for the two respiratory systems despite their largely conserved proton-pumping mechanisms. The Na+-translocating unit, absent in complex I, resembles that found in the Mrp H+/Na+ antiporter and enables hydrogen gas evolution by MBH to establish a Na+ gradient for ATP synthesis near 100°C. MBH also provides insights into Mrp structure and evolution of MBH-based respiratory enzymes.