Dimeric structures of quinol-dependent nitric oxide reductases (qNORs) revealed by cryo–electron microscopy

Gopalasingam, CC, Johnson, RM, Chiduza, GN ORCID: 0000-0003-1037-5749, Tosha, T, Yamamoto, M, Shiro, Y, Antonyuk, SV ORCID: 0000-0002-2779-9946, Muench, SP and Samar Hasnain, S
(2019) Dimeric structures of quinol-dependent nitric oxide reductases (qNORs) revealed by cryo–electron microscopy. Science Advances, 5 (8). eaax1803-.

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Copyright © 2019 The Authors, some rights reserved; Quinol-dependent nitric oxide reductases (qNORs) are membrane-integrated, iron-containing enzymes of the denitrification pathway, which catalyze the reduction of nitric oxide (NO) to the major ozone destroying gas nitrous oxide (N2O). Cryo–electron microscopy structures of active qNOR from Alcaligenes xylosoxidans and an activity-enhancing mutant have been determined to be at local resolutions of 3.7 and 3.2 Å, respectively. They unexpectedly reveal a dimeric conformation (also confirmed for qNOR from Neisseria meningitidis) and define the active-site configuration, with a clear water channel from the cytoplasm. Structure-based mutagenesis has identified key residues involved in proton transport and substrate delivery to the active site of qNORs. The proton supply direction differs from cytochrome c–dependent NOR (cNOR), where water molecules from the cytoplasm serve as a proton source similar to those from cytochrome c oxidase.

Item Type: Article
Uncontrolled Keywords: Cytoplasm, Escherichia coli, Protons, Nitric Oxide, Hydroquinones, Electron Transport Complex IV, Oxidoreductases, Bacterial Proteins, Cryoelectron Microscopy, Catalytic Domain, Oxidation-Reduction
Depositing User: Symplectic Admin
Date Deposited: 05 Sep 2019 09:57
Last Modified: 19 Jan 2023 00:27
DOI: 10.1126/sciadv.aax1803
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3053545