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Publication Abstract from PubMed

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 degrees 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 degrees C. MBH also provides insights into Mrp structure and evolution of MBH-based respiratory enzymes.

Structure of an Ancient Respiratory System.,Yu H, Wu CH, Schut GJ, Haja DK, Zhao G, Peters JW, Adams MWW, Li H Cell. 2018 Apr 25. pii: S0092-8674(18)30403-3. doi: 10.1016/j.cell.2018.03.071. PMID:29754813^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.