28pn

CryoEM structure of native quinol dependent Nitric Oxide Reductase at pH 8.0 on gold grid.

spinqualitylabelsall models 28pn, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 28pn is a 2 chain structure with sequence from Achromobacter xylosoxidans. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.7Å Ligands: CA, FE, HEM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed The membrane-bound quinol-dependent nitric oxide reductases (qNORs), which are members of the respiratory heme-copper oxidase superfamily, are of major importance to food production, environment, and human health. They are unique to bacteria and catalyze N-N bond formation, converting nitric oxide (NO) to generate the enzymatic product, nitrous oxide (N(2)O), in agricultural and pathogenic conditions. High-resolution qNOR structures have been reported from two bacterial species, in which the molecular size of the protein was increased by the insertion of apocytochrome b(562) (BRIL) at the C-terminus to facilitate cryoEM structure determination. However, it remains uncertain how BRIL fusion alters the native structure of these metalloenzymes. Here, we present the first high-resolution structure of Achromobacter xylosoxidans qNOR (AxqNOR) determined without a fusion tag at two different pH values, revealing structural differences near the catalytic core as well as overall conformational changes between the native and fusion-tagged structures. The native enzyme shows a bell-shaped pH dependence of enzymatic activity, like nitrite reductase, the preceding enzyme in the denitrification pathway, which generates the substrate NO. In addition, we report structures of AxqNOR bound to quinol and hydroxyquinol that provide valuable insight into the potential electron transfer pathway originating from Trp718 to the redox centers. CryoEM Structures of Native Quinol-Dependent Nitric Oxide Reductase in Resting and Quinol-Bound States.,Khaja FT, Mboukou A, Aspinall LP, Hawksworth CE, Eady RR, Antonyuk SV, Muench SP, Hasnain SS ACS Bio Med Chem Au. 2026 Mar 13;6(2):145-159. doi: , 10.1021/acsbiomedchemau.5c00245. eCollection 2026 Apr 15. PMID:42006251 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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