Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.4 (nitrite reductase)
 1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pseudomonas stutzeri is a facultative anaerobic bacterium with the capability of denitrification. In searching for regulators that control the expression of this trait in response to oxygen withdrawal, we have found an unprecedented multiplicity of four genes encoding transcription factors of the FNR family. The fnrA gene encodes a genuine FNR-type regulator, which is expressed constitutively and controls the cytochrome cbb3-type terminal oxidase (the cco operon), cytochrome c peroxidase (the ccp gene) and the oxygen-independent coproporphyrinogen III oxidase (the hemN gene), in addition to its previously demonstrated role in arginine catabolism (the arc operon). The fnr homologues dnrD, dnrE and dnrS encode regulators of a new subgroup within the FNR family. Their main distinctive feature is the lack of cysteine residues for complexing the [4Fe-4S] centre of redox-active FNR-type regulators. However, they form a phylogenetic lineage separate from the FixK branch of FNR proteins, which also lack this cysteine signature. We have studied the expression of the dnr genes under aerobic, oxygen-limited and denitrifying conditions. DnrD is a key regulator of denitrification by selective activation of the genes for cytochrome cd1 nitrite reductase and NO reductase. The dnrD gene is part of the 30 kb region carrying denitrification genes of P. stutzeri. Transcription of dnrD was activated in O2-limited cells and particularly strongly in denitrifying cells, but was not under the control of FnrA. In response to denitrifying growth conditions, dnrD was transcribed as part of an operon together with genes downstream and upstream of dnrD. dnrS was found about 9 kb upstream of dnrD, next to the nrdD gene for anaerobic ribonucleotide reductase. The transcription of dnrS required FnrA in O2-limited cells. Mutation of dnrS affected nrdD and the expression of ferredoxin I as an element of the oxidative stress response. The dnrE gene is part of the nar region encoding functions for respiratory nitrate reduction. We found the highest amount of dnrE transcripts in aerobically nitrate-challenged cells. The gene was transcribed from two promoters, P1 and P2, of which promoter P1 was under the control of the nitrate response regulator NarL. The multiplicity of FNR factors in P. stutzeri underlines the versatility of the FNR scaffold to serve for transcriptional regulation directed at anaerobic or nitrate-activated metabolic processes.
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PMID:Multiple transcription factors of the FNR family in denitrifying Pseudomonas stutzeri: characterization of four fnr-like genes, regulatory responses and cognate metabolic processes. 1020 42

Campylobacter jejuni is a small genome pathogen that is incapable of growing strictly anaerobically due to its dependence on an oxygen-requiring ribonucleotide reductase for DNA synthesis. Nevertheless, it has a complex branched respiratory chain, which allows the use of several alternative electron acceptors for growth under oxygen-limited conditions. C. jejuni is equipped with both nitrate reductase (Nap) and nitrite reductase (Nrf) located in the periplasm, each predicted to receive electrons from menaquinol through distinct redox proteins. The pathways of electron transport to nitrate and nitrite are reviewed in this paper. Nitrate is considered as a potential in vivo electron acceptor and a role for nitrite reductase in NO detoxification is suggested.
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PMID:Electron transport through nitrate and nitrite reductases in Campylobacter jejuni. 1566 3