1.8.5.4: bacterial sulfide:quinone reductase
This is an abbreviated version!
For detailed information about bacterial sulfide:quinone reductase, go to the full flat file.
Word Map on EC 1.8.5.4
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1.8.5.4
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sulfur
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h2s
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thiosulfate
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persulfide
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polysulfide
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acidithiobacillus
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sulfurtransferase
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sulfide-oxidizing
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rhodanese
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sulfane
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ferrooxidans
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3-mercaptopyruvate
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anoxygenic
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sulfur-oxidizing
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chemolithotrophic
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sulfide-dependent
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echiuran
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unicinctus
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limnetica
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urechis
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monotopic
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oscillatoria
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tepidum
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chlorobaculum
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sulfide-rich
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medicine
- 1.8.5.4
- sulfur
- h2s
- thiosulfate
- persulfide
- polysulfide
- acidithiobacillus
- sulfurtransferase
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sulfide-oxidizing
- rhodanese
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sulfane
- ferrooxidans
- 3-mercaptopyruvate
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anoxygenic
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sulfur-oxidizing
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chemolithotrophic
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sulfide-dependent
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echiuran
- unicinctus
- limnetica
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urechis
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monotopic
- oscillatoria
- tepidum
- chlorobaculum
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sulfide-rich
- medicine
Reaction
n HS- + n quinone = + n quinol
Synonyms
CmSQR, CpSQR, CT1087, HMT2, III SQR, membrane-bound sulfide:quinone oxidoreductases, SQOR, SQR, Sqrdl, sqrF, Suden_1879, Suden_2082, Suden_619, sulfide quinone oxidoreductase, sulfide quinone reductase, sulfide-quinone oxidoreductase, sulfide-quinone reductase, sulfide: quinone oxidoreductase, sulfide:decylubiquinone oxidoreductase, sulfide:quinone oxidoreductase, sulfidequinone reductase-like protein, TrSqrF, type I SQR, type III sulfide:quinone oxidoreductase, type VI sulfide:quinone oxidoreductase
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General Information
General Information on EC 1.8.5.4 - bacterial sulfide:quinone reductase
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evolution
malfunction
metabolism
physiological function
additional information
SQR proteins are classified into six types (types I-VI, SqrA-F). The photosynthetic purple sulfur bacterium, Thiocapsa roseopersicina contains a type VI SQR enzyme (TrSqrF) having unusual catalytic parameters and four cysteines likely involved in the catalysis. Multiple sequence alignment of selected representative SQR proteins with conserved cysteines in the primary sequence of various sulfide:quinone oxidoreductases (Aquifex aeolicus and Thiocapsa roseopersicina residue numbering) with approximate location of conserved cysteines in relation to the isoalloxazine ring of FAD, based on the structures of various sulfide:quinone oxidoreductases, overview
evolution
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SQRs belong to the two-dinucleotide-binding-domains flavoprotein (tDBDF) superfamily, characterized by the presence of two Rossmann fold domains known to stabilize the adenosine moieties of dinucleotides (e.g. FAD and NADH). SQRs are typically oligomeric flavoproteins with multiple copies of a single subunit of molecular mass of about 50 kDa. SQRs are associated with the prokaryotic cytoplasmic or periplasmic membrane or the inner mitochondrial membrane
evolution
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SQRs belong to the two-dinucleotide-binding-domains flavoprotein (tDBDF) superfamily, characterized by the presence of two Rossmann fold domains known to stabilize the adenosine moieties of dinucleotides (e.g. FAD and NADH). SQRs are typically oligomeric flavoproteins with multiple copies of a single subunit of molecular mass of about 50 kDa. SQRs are associated with the prokaryotic cytoplasmic or periplasmic membrane or the inner mitochondrial membrane
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a DELTAsqr mutant contains less cellular sulfur (S0) and has increased expression of key genes involved in photosynthesis, but it is less competitive than the wild-type in cocultures. Strain PCC7002 uses SQR to detoxify exogenous sulfide, enabling it to survive better than its DELTAsqr mutant in sulfide-rich environments. The wild-type strain PCC7002 and the complementation strain PCC7002DELTAsqr::sqr do not accumulate sulfide, but the mutant DELTAsqr does. The DELTAsqr mutant has a higher oxygen evolution rate than the wild-type. The increased oxygen evolution rate upon the DELTAsqr mutant is consistent with an acceleration of H2O oxidation to make up for the loss of H2S oxidation, phenotype, overview
malfunction
enzyme Sqr knockout leads to morphological changes and functional deficiencies of mitochondria and apoptosis in Schizosaccharomyces pombe. The Sqr knockout strain displays the same phenotypes as the cysteine-synthesis-deficient strain. Cysteine addition complements the effects caused by Sqr knockout. Sqr knockout also results in physiological changes. The DELTAsqr strain shows reduced cell viability compared to the wild-type strain when cultivated in YES medium. There are more cells of early apoptosis in DELTAsqr culture than that in wild-type culture. Sqr knockout impaires mitochondrial health. Phenotypes and transcription and metabolism changes caused by sqr knockout, overview
malfunction
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enzyme Sqr knockout leads to morphological changes and functional deficiencies of mitochondria and apoptosis in Schizosaccharomyces pombe. The Sqr knockout strain displays the same phenotypes as the cysteine-synthesis-deficient strain. Cysteine addition complements the effects caused by Sqr knockout. Sqr knockout also results in physiological changes. The DELTAsqr strain shows reduced cell viability compared to the wild-type strain when cultivated in YES medium. There are more cells of early apoptosis in DELTAsqr culture than that in wild-type culture. Sqr knockout impaires mitochondrial health. Phenotypes and transcription and metabolism changes caused by sqr knockout, overview
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malfunction
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enzyme Sqr knockout leads to morphological changes and functional deficiencies of mitochondria and apoptosis in Schizosaccharomyces pombe. The Sqr knockout strain displays the same phenotypes as the cysteine-synthesis-deficient strain. Cysteine addition complements the effects caused by Sqr knockout. Sqr knockout also results in physiological changes. The DELTAsqr strain shows reduced cell viability compared to the wild-type strain when cultivated in YES medium. There are more cells of early apoptosis in DELTAsqr culture than that in wild-type culture. Sqr knockout impaires mitochondrial health. Phenotypes and transcription and metabolism changes caused by sqr knockout, overview
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SQR is involved in elemental sulfur oxidation in sulfur-grown cells
metabolism
the enzyme plays a key role in the sulfide-dependent respiration and anaerobic photosynthesis
metabolism
in Schizosaccharomyces pombe, Sqr is the main reactive sulfur species (RSS) producer in mitochondria, and RSS instead of H2S is used by cysteine synthase to synthesize cysteine. In terms of RSS metabolism, Schizosaccharomyces pombe does not contain genes encoding cystathionine beta-synthase (Cbs), cystathionine gamma-lyase (Cse), cysteinyl-tRNA synthetase 2 (Crs2), or persulfide dioxygenase (Pdo)
metabolism
mammalian mitochondria and heterotrophic bacteria oxidize sulfide via a pathway involving two key enzymes, sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO, EC 1.13.11.18). SQR oxidizes sulfide to polysulfide, which spontaneously reacts with glutathione (GSH) to produce glutathione persulfide (GSSH), PDO oxidizes GSSH to sulfite, which spontaneously reacts with polysulfide to produce thiosulfate. This pathway is common in heterotrophic bacteria. The relative electron transport rate (rETR) increases in the mutant
metabolism
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in Schizosaccharomyces pombe, Sqr is the main reactive sulfur species (RSS) producer in mitochondria, and RSS instead of H2S is used by cysteine synthase to synthesize cysteine. In terms of RSS metabolism, Schizosaccharomyces pombe does not contain genes encoding cystathionine beta-synthase (Cbs), cystathionine gamma-lyase (Cse), cysteinyl-tRNA synthetase 2 (Crs2), or persulfide dioxygenase (Pdo)
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metabolism
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in Schizosaccharomyces pombe, Sqr is the main reactive sulfur species (RSS) producer in mitochondria, and RSS instead of H2S is used by cysteine synthase to synthesize cysteine. In terms of RSS metabolism, Schizosaccharomyces pombe does not contain genes encoding cystathionine beta-synthase (Cbs), cystathionine gamma-lyase (Cse), cysteinyl-tRNA synthetase 2 (Crs2), or persulfide dioxygenase (Pdo)
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metabolism
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SQR is involved in elemental sulfur oxidation in sulfur-grown cells
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SQR and the cytochrome bc complex are involved in sulfide-dependent respiration. Oxidation of sulfide by SQR is coupled, at least in part, to the proton-motive Q-cycle mechanism
physiological function
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SQR is involved in sulfide detoxification, in sulfide-dependent energy conservation processes and potenatially in the homeostasis of the neurotransmitter sulfide
physiological function
SQR is involved in sulfide detoxification, in sulfide-dependent energy conservation processes and potentially in the homeostasis of the neurotransmitter sulfide
physiological function
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sulfide-quinone reductase catalyzes anoxygenic photosynthesis in Oscillatoria limnetica
physiological function
sulfide-quinone reductase is essential for photoautotrophic growth on sulfide and is involved in energy conversion, but not in detoxification
physiological function
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sulfide:quinone oxidoreductases are ubiquitous enzymes which have multiple roles: sulfide detoxification, energy generation by providing electrons to respiratory or photosynthetic electron transfer chains, and sulfide homeostasis
physiological function
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human sulfide quinone oxidoreductase uses glutathione as an acceptor forming glutathione persulfide (GSSH), which is preferentially converted to thiosulfate by human rhodanese
physiological function
in bacteria, sulfide:quinone oxidoreductase (SQR) oxidizes sulfide to polysulfide, rhodanese speeds up the reaction of polysulfide with glutathione (GSH) to produce glutathione persulfide (GSSH), and persulfide dioxygenase (PDO) oxidizes GSSH to sulfite, which spontaneously reacts with polysulfide to produce thiosulfate. Ubiquinone is a cosubstrate in the reaction
physiological function
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sulfide:quinone oxidoreductase (SQR) is a monotopic membrane flavoprotein present in all domains of life, with multiple roles including sulfide detoxification, homeostasis and energy generation by providing electrons to respiratory or photosynthetic electron transport chains
physiological function
sulfide:quinone oxidoreductase (Sqr), which oxidizes hydrogen sulfide to reactive sulfur species (RSS), is indispensable to mitochondria health in the eukaryotic model microorganism Schizosaccharomyces pombe. RSS play critical functions in the cell, such as signaling, redox homeostasis maintenance, and metabolic regulation
physiological function
the toxic effect of sulfide is well known, inhibiting respiration by acting on cytochrome c oxidase in heterotrophic bacteria and photosynthesis by binding to metalloproteins of photosynthesis system II (PSII). Sulfide can reach high concentrations in specific habitats, such as hydrothermal vents and seeps and coastal mudflats. Synechococcus sp. strain PCC 7002 uses sulfide:quinone oxidoreductase to detoxify exogenous sulfide and to convert endogenous sulfide to cellular sulfane sulfur. SQR plays a detoxification role. Strain PCC7002 with SQR and persulfide dioxygenase (PDO, EC 1.13.11.18) oxidizes exogenous sulfide to tolerate high sulfide levels. Common presence of SQR in cyanobacteria. SQRs are widely distributed in microorganisms as well as in animal mitochondria. SQR oxidizes sulfide to polysulfide and transfers electrons into the electron transport chain in mitochondria, heterotrophic bacteria, chemolithotrophic bacteria, and photolithotrophic bacteria
physiological function
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sulfide:quinone oxidoreductases are ubiquitous enzymes which have multiple roles: sulfide detoxification, energy generation by providing electrons to respiratory or photosynthetic electron transfer chains, and sulfide homeostasis
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physiological function
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sulfide:quinone oxidoreductase (SQR) is a monotopic membrane flavoprotein present in all domains of life, with multiple roles including sulfide detoxification, homeostasis and energy generation by providing electrons to respiratory or photosynthetic electron transport chains
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physiological function
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sulfide-quinone reductase is essential for photoautotrophic growth on sulfide and is involved in energy conversion, but not in detoxification
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physiological function
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sulfide:quinone oxidoreductase (Sqr), which oxidizes hydrogen sulfide to reactive sulfur species (RSS), is indispensable to mitochondria health in the eukaryotic model microorganism Schizosaccharomyces pombe. RSS play critical functions in the cell, such as signaling, redox homeostasis maintenance, and metabolic regulation
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physiological function
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sulfide:quinone oxidoreductase (Sqr), which oxidizes hydrogen sulfide to reactive sulfur species (RSS), is indispensable to mitochondria health in the eukaryotic model microorganism Schizosaccharomyces pombe. RSS play critical functions in the cell, such as signaling, redox homeostasis maintenance, and metabolic regulation
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reactive sulfur species (RSS) include inorganic polysulfide (HSnH, n>2), organic polysulfide (RSnH, n>2), and polysulfane (RSnR, n>2)
additional information
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residue Gly299 is only important for quinone reduction despite its proximity to bound FAD. Residues Phe337 and Phe362 are also important for quinone binding apparently by direct interaction with the quinone ring, whereas Lys359, postulated to hydrogen bond to the quinone, seems to have a more structural role. Three-dimensional homology model of Caldivirga maquilingensis SQR
additional information
structure homology modelling, molecular mechanics and molecular dynamics calculations, overview. Analysis of interactions between the protein and ligands, calculation of solvent accessible surface (SAS) and energy value. The structural stability of the alpha-helix in the C-terminus of enzyme SQR has an important influence on the structural stability of the whole protein
additional information
sulfane sulfur is zero valence sulfur in various forms, such as persulfide (RSSH), polysulfide (RSSnH and RSSnR, nx022), and elemental sulfur. Sulfane sulfur can act as either an electrophile or a nucleophile. The nucleophilic property allows cells to resist reactive oxygenspecies, and the electrophilic property causes protein persulfidation, affecting enzyme activities or signaling
additional information
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residue Gly299 is only important for quinone reduction despite its proximity to bound FAD. Residues Phe337 and Phe362 are also important for quinone binding apparently by direct interaction with the quinone ring, whereas Lys359, postulated to hydrogen bond to the quinone, seems to have a more structural role. Three-dimensional homology model of Caldivirga maquilingensis SQR
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additional information
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reactive sulfur species (RSS) include inorganic polysulfide (HSnH, n>2), organic polysulfide (RSnH, n>2), and polysulfane (RSnR, n>2)
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additional information
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reactive sulfur species (RSS) include inorganic polysulfide (HSnH, n>2), organic polysulfide (RSnH, n>2), and polysulfane (RSnR, n>2)
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