6QQ6

Cryo-EM structure of dimeric quinol dependent nitric oxide reductase (qNOR) Val495Ala mutant from Alcaligenes xylosoxidans

Summary for 6QQ6

• Entry DOI: 10.2210/pdb6qq6/pdb
• EMDB information: 4618 4619
• Descriptor: Nitric oxide reductase subunit B, PROTOPORPHYRIN IX CONTAINING FE, FE (III) ION, ... (7 entities in total)
• Functional Keywords: proton transfer, membrane protein, homodimer, oxidoreductase
• Biological source: Alcaligenes xylosoxydans xylosoxydans (Achromobacter xylosoxidans)
• Total number of polymer chains: 2
• Total formula weight: 171852.57

Authors

Gopalasingam, C.C.,Johnson, R.M.,Chiduza, G.N.,Tosha, T.,Yamamoto, M.,Shiro, Y.,Antonyuk, S.V.,Muench, S.P.,Hasnain, S.S. (deposition date: 2019-02-17, release date: 2019-09-11, Last modification date: 2024-05-15)

Primary citation

Gopalasingam, C.C.,Johnson, R.M.,Chiduza, G.N.,Tosha, T.,Yamamoto, M.,Shiro, Y.,Antonyuk, S.V.,Muench, S.P.,Hasnain, S.S.
Dimeric structures of quinol-dependent nitric oxide reductases (qNORs) revealed by cryo-electron microscopy.
Sci Adv, 5:eaax1803-eaax1803, 2019

PubMed Abstract: 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 (NO). Cryo-electron microscopy structures of active qNOR from 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 ) 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.

PubMed: 31489376
DOI: 10.1126/sciadv.aax1803

Experimental method

ELECTRON MICROSCOPY (3.3 Å)