28PP

CryoEM structure of native quinol dependent Nitric Oxide Reductase Arg720Ala variant at pH 6.5 on gold grid.

28PP の概要

• エントリーDOI: 10.2210/pdb28pp/pdb
• EMDBエントリー: 56720
• 分子名称: Nitric oxide reductase subunit B, PROTOPORPHYRIN IX CONTAINING FE, CALCIUM ION, ... (5 entities in total)
• 機能のキーワード: quinol-dependent nitric oxide reductase, membrane protein
• 由来する生物種: Achromobacter xylosoxidans
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 171935.29

構造登録者

Khaja, F.,Antonyuk, S.V.,Muench, S.P.,Hasnain, S.S. (登録日: 2026-02-12, 公開日: 2026-05-06)

主引用文献

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

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: 42006251
DOI: 10.1021/acsbiomedchemau.5c00245

実験手法

ELECTRON MICROSCOPY (2.9 Å)