Characterization of the quinol-dependent nitric oxide reductase from the pathogen Neisseria meningitidis, an electrogenic enzyme.
Characterization of the quinol-dependent nitric oxide reductase from the pathogen Neisseria meningitidis, an electrogenic enzyme.
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DOI：
10.1038/s41598-018-21804-0
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发表时间：
2018-02-26
影响因子：
4.6
通讯作者：
Ädelroth P
中科院分区：
文献类型：
--
作者：
Gonska N;Young D;Yuki R;Okamoto T;Hisano T;Antonyuk S;Hasnain SS;Muramoto K;Shiro Y;Tosha T;Ädelroth P
细菌一氧化氮还原酶（NORs）催化NO还原为N2 O和H2O。NORs存在于反硝化链或病原体中，其主要作用是对宿主免疫防御产生的NO进行解毒。虽然NOR属于血红素-铜氧化酶超家族，包括质子泵O2还原酶，但研究最多的NOR，cNOR（细胞色素c依赖性），是非产电的。在这里，我们关注另一种类型的NOR，qNOR（喹啉依赖性）。重组qNOR脑膜炎奈瑟氏菌，人类病原体，纯化大肠杆菌，表现出高催化活性和光谱特性很大程度上类似于cNOR。然而，与cNOR相反，脂质体重建的qNOR显示呼吸控制比高于2，表明qNOR的NO还原是生电的。此外，我们还测定了N.脑膜炎病毒qNOR，允许通过诱变探索来自细胞质的潜在质子转移途径。大多数突变对活性几乎没有影响，然而E-498变体在很大程度上是无活性的，而cNOR中的相应取代先前显示不诱导显著影响。因此，我们认为，与cNOR相反，N。脑膜炎qNOR使用细胞质质子进行NO还原。我们的研究结果允许质子的可能路线进行讨论。
Bacterial nitric oxide reductases (NORs) catalyse the reduction of NO to N2O and H2O. NORs are found either in denitrification chains, or in pathogens where their primary role is detoxification of NO produced by the immune defense of the host. Although NORs belong to the heme-copper oxidase superfamily, comprising proton-pumping O2-reducing enzymes, the best studied NORs, cNORs (cytochrome c-dependent), are non-electrogenic. Here, we focus on another type of NOR, qNOR (quinol-dependent). Recombinant qNOR from Neisseria meningitidis, a human pathogen, purified from Escherichia coli, showed high catalytic activity and spectroscopic properties largely similar to cNORs. However, in contrast to cNOR, liposome-reconstituted qNOR showed respiratory control ratios above two, indicating that NO reduction by qNOR was electrogenic. Further, we determined a 4.5 Å crystal structure of the N. meningitidis qNOR, allowing exploration of a potential proton transfer pathway from the cytoplasm by mutagenesis. Most mutations had little effect on the activity, however the E-498 variants were largely inactive, while the corresponding substitution in cNOR was previously shown not to induce significant effects. We thus suggest that, contrary to cNOR, the N. meningitidis qNOR uses cytoplasmic protons for NO reduction. Our results allow possible routes for protons to be discussed.
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