Cytochrome P-450 55A1 (P-450dNIR) acts as nitric oxide reductase employing NADH as the direct electron donor.

Nakahara, Kazuhiko; Tanimoto, Tatsuo; Hatano, Ken-ichi; Usuda, Keisuke; Shoun, Hirofumi

doi:10.1016/s0021-9258(18)53102-1

Cited by 236 publications

(84 citation statements)

References 21 publications

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“…P450nor is found in soil dwelling fungi and yeasts and operates with a single heme b cofactor in the active site that features a proximally bound cysteinate residue, the hallmark of the Cyt. P450 superfamily. ,, This is in contrast to bacterial NORs which perform NO reduction using a dinuclear heme/non-heme iron active site, as discussed in Section . Additionally, in bacterial denitrification, nitrate is reduced to dinitrogen as the ultimate product, whereas fungal denitrification ends with N 2 O, which is subsequently released into the atmosphere. , Because of widespread overfertilization of agricultural soils, which stimulates nitrification and denitrification, fungal N 2 O production is thought to make a large contribution to global N 2 O emissions, contributing to climate change .…”

Section: The Nitrogen Cyclementioning

confidence: 99%

“…In the first step of the reaction, the ferric heme binds NO to form a ls-{FeNO} complex. This step is followed by a direct hydride transfer from NAD(P)H to the ferric NO complex, which generates the so-called “Intermediate I”. This species corresponds to a ls-{FeNH n O} type complex, but its protonation state (n = 1 or 2) is unknown. − Intermediate I is catalytically competent to react with a second molecule of NO to generate N 2 O, which completes the catalytic cycle. ,− In bacterial rNORs, c NOR (or NorBC) is the main representative, but this enzyme family also includes qNOR and Cu A NOR, where the “ c ”, “q”, and “Cu A ” refer to different electron transfer sites. , In all cases, the active site contains a high-spin heme b , termed heme b 3 (due to its analogy to heme a 3 in C c Os), and an adjacent non-heme iron center, called Fe B .…”

Section: Introductionmentioning

confidence: 99%

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The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity

et al. 2021

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Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.

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Section: The Nitrogen Cyclementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity

et al. 2021

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“…So we suggested that the fungus had acquired the P450 gene from actinomycetes by horizontal transfer [32]. Once the fungal denitrification was found, it was rather easy to find the physiological function of CYP55 as Nor (P450nor) [8] because it was involved in denitrification. However, it took 10 years after its isolation to elucidate its physiological function.…”

Section: Cytochrome P450nor (Fungal Nitric Oxide Reductase)mentioning

confidence: 99%

“…The most characteristic feature of the fungal-denitrifying system is the involvement of cytochrome P450 (P450) as nitric oxide reductase (P450nor) [8,9]. Since then, many papers from other groups have also shown that fungal denitrification functions in nature as a major process in the nitrogen cycle [10 -13].…”

Section: Introductionmentioning

confidence: 99%

Fungal denitrification and nitric oxide reductase cytochrome P450nor

Shoun

Fushinobu

Jiang

et al. 2012

Phil. Trans. R. Soc. B

219

189

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We have shown that many fungi (eukaryotes) exhibit distinct denitrifying activities, although occurrence of denitrification was previously thought to be restricted to bacteria (prokaryotes), and have characterized the fungal denitrification system. It comprises NirK (copper-containing nitrite reductase) and P450nor (a cytochrome P450 nitric oxide (NO) reductase (Nor)) to reduce nitrite to nitrous oxide (N 2 O). The system is localized in mitochondria functioning during anaerobic respiration. Some fungal systems further contain and use dissimilatory and assimilatory nitrate reductases to denitrify nitrate. Phylogenetic analysis of nirK genes showed that the fungal-denitrifying system has the same ancestor as the bacterial counterpart and suggested a possibility of its proto-mitochondrial origin. By contrast, fungi that have acquired a P450 from bacteria by horizontal transfer of the gene, modulated its function to give a Nor activity replacing the original Nor with P450nor. P450nor receives electrons directly from nicotinamide adenine dinucleotide to reduce NO to N 2 O. The mechanism of this unprecedented electron transfer has been extensively studied and thoroughly elucidated. Fungal denitrification is often accompanied by a unique phenomenon, co-denitrification, in which a hybrid N 2 or N 2 O species is formed upon the combination of nitrogen atoms of nitrite with a nitrogen donor (amines and imines). Possible involvement of NirK and P450nor is suggested.

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“…The first, a eukaryotic example, is CYP55A1 (P450nor) discovered in the fungus F. oxysporum. Biochemically, CYP55A1 catalyses the reduction of nitric oxide to nitrous oxide [33]. CYP55A1 is a soluble P450 and, although encoded by the same gene, is located in both the cytoplasm and mitochondria in the cell.…”

Section: Unusual P450 Systems and Associated Redox Partnersmentioning

confidence: 99%

Unusual properties of the cytochrome P450 superfamily

Lamb

Waterman

2013

Phil. Trans. R. Soc. B

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During the early years of cytochrome P450 research, a picture of conserved properties arose from studies of mammalian forms of these monooxygenases. They included the protohaem prosthetic group, the cysteine residue that coordinates to the haem iron and the reduced CO difference spectrum. Alternatively, the most variable feature of P450s was the enzymatic activities, which led to the conclusion that there are a large number of these enzymes, most of which have yet to be discovered. More recently, studies of these enzymes in other eukaryotes and in prokaryotes have led to the discovery of unexpected P450 properties. Many are variations of the original properties, whereas others are difficult to explain because of their unique nature relative to the rest of the known members of the superfamily. These novel properties expand our appreciation of the broad view of P450 structure and function, and generate curiosity concerning the evolution of P450s. In some cases, structural properties, previously not found in P450s, can lead to enzymatic activities impacting the biological function of organisms containing these enzymes; whereas, in other cases, the biological reason for the variations are not easily understood. Herein, we present particularly interesting examples in detail rather than cataloguing them all.

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Cytochrome P-450 55A1 (P-450dNIR) acts as nitric oxide reductase employing NADH as the direct electron donor.

Cited by 236 publications

References 21 publications

The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity

The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity

Fungal denitrification and nitric oxide reductase cytochrome P450nor

Unusual properties of the cytochrome P450 superfamily

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