28PQ
CryoEM structure of native quinol dependent Nitric Oxide Reductase Trp718Ala variant at pH 6.5 on gold grid.
Summary for 28PQ
| Entry DOI | 10.2210/pdb28pq/pdb |
| EMDB information | 56721 |
| Descriptor | Nitric oxide reductase subunit B, PROTOPORPHYRIN IX CONTAINING FE, CALCIUM ION, ... (7 entities in total) |
| Functional Keywords | quinol-dependent nitric oxide reductase, membrane protein |
| Biological source | Achromobacter xylosoxidans |
| Total number of polymer chains | 2 |
| Total formula weight | 173931.86 |
| Authors | Khaja, F.,Antonyuk, S.V.,Muench, S.P.,Hasnain, S.S. (deposition date: 2026-02-12, release date: 2026-05-06) |
| Primary citation | Khaja, F.T.,Mboukou, A.,Aspinall, L.P.,Hawksworth, C.E.,Eady, R.R.,Antonyuk, S.V.,Muench, S.P.,Hasnain, S.S. CryoEM Structures of Native Quinol-Dependent Nitric Oxide Reductase in Resting and Quinol-Bound States. Acs Bio Med Chem Au, 6:145-159, 2026 Cited by PubMed Abstract: 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 (NO), 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 (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 qNOR (qNOR) 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 qNOR bound to quinol and hydroxyquinol that provide valuable insight into the potential electron transfer pathway originating from Trp718 to the redox centers. PubMed: 42006251DOI: 10.1021/acsbiomedchemau.5c00245 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.4 Å) |
Structure validation
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