6CFW

Structure of an Ancient Respiratory System.

(2018) Cell 173: 1636

• PubMed: 29754813 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1016/j.cell.2018.03.071
• Primary Citation of Related Structures:  
  6CFW


• PubMed 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.

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Organizational Affiliation: 

Cryo-EM Structural Biology Laboratory, Van Andel Research Institute, Grand Rapids, MI 49503, USA.