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Sulfide:quinone reductase

January 01, 1970

Sulfide:quinone reductase (SQR , EC 1.8.5.4) is an enzyme with systematic name sulfide:quinone oxidoreductase.[1][2][3][4][5][6] This enzyme catalyses the following chemical reaction

Sulfide:quinone reductase
Identifiers
EC no.1.8.5.4
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Search
PMCarticles
PubMedarticles
NCBIproteins
n HS− + n quinone polysulfide + n quinol

SQR contains FAD. Ubiquinone, plastoquinone or menaquinone can act as acceptor in different species.

The Enzyme Commission (EC) number for SQR is 1.8.5.’. The number indicates that the protein is an oxidoreductase (indicated by 1). The oxidoreductase reacts with a sulfur molecule (sulfide in this case) to donate electrons (indicated by 8). The donated electrons are accepted by a quinone (indicated by 5).[7] Multiple sulfide:quinone oxidoreductases are found in bacteria, archaea, and eukaryotes, but the function highlighted in the EC numbers 1.8.5.’. are all constant except that the final digit with is 4 in bacteria and 8 in eukaryotic mitochondria.[8][7]

Crystalline structure edit

The SQR in Aquifex aeolicus is composed of three subunits with a negatively charged hydrophilic side exposed to the periplasmic space and a hydrophobic region that integrates into the cell’s plasma membrane. The protein's active site is composed of an FAD cofactor covalently linked by a thioether bond to the enzyme. On the si side of the FAD the sulfide reacts and donates its electrons to FAD, while the re side of FAD is connected to a disulfide bridge and donates electrons to the quinone. 2, 3 The quinone is surrounded by Phe-385 and Ile-346. Both amino acids are located in the hydrophobic region of the plasma membrane and are conserved among all sulfide: quinone oxidoreductases.[9]

Reaction Pathway edit

In A. aeolicus, SQR is an integral monotopic protein, so it penetrates into the hydrophobic region of the plasma membrane. The SQR reaction takes place in two half reactions, sulfide oxidation and quinone reduction. The active site of SQR is composed of a region that interacts with the periplasmic space and sulfide connected by a FAD cofactor and a trisulfide bridge to a quinone. FAD receives two electrons from sulfide and transfers the electrons one at time to the quinone. The amino acids surrounding the quinone are all hydrophobic. Also, there is a highly conserved region of uncharged amino acids, phenylalanine and isoleucine, that surround the benzene ring of the quinone.[10]

SQR is a member of the flavoprotein disulfide reductase (FDR) superfamily. FDRs are typically characterized as being dimeric or two subunit proteins, but sulfide quinone oxidoreductase is a trimeric protein. The main purpose of SQR is to detoxify sulfide. Sulfide is a toxic chemical that inhibits enzymatic reactions, especially those with metal cofactors. Most notably, sulfide inhibits cytochrome oxidase found in the electron transport chain. SQR oxidizes sulfide and produces non-toxic products.[11]

Role in metabolism edit

SQR is an integral protein that enters cells' plasma membrane (or inner mitochondrial membrane).[12] The plasma membrane is the site of the electron transport chain for respiration.[13] The electron transport chain depends on two factors: 1) ability of a membrane to store an ion gradient; 2) the ability of an organism to pump hydrogen ions against a gradient (from low to high concentration).[12] SQR enhances the formation of an ion gradient by donating two electrons to the quinone.[13] Once the electrons are in the quinone, they are transported to the quinone pool.[12] The quinone pool is located inside the hydrophobic region of the plasma membrane and plays a role in transporting hydrogen ions to the periplasm. From the quinone pool, electrons travel to cytochrome c oxidase where oxygen is waiting as the final electron acceptor.[12][13]

Electrons from carbon sources react in a similar fashion to those in sulfide. Two main differences separate the carbon pathway and the sulfur pathway: 1) sulfur (sulfide in this case) skips glycolysis and the tricarboxylic acid cycle (TCA), while the carbon pathway requires both cycles to store electrons in NADHl[10][14] 2) electrons from sulfide are donated to SQR, while the electrons from NADH are donated to the NADH:quinone oxidoreductase.[14] In both cases, the electrons are shuttled to the quinone pool, then to cytochrome c oxidase where the final electron acceptor is waiting.[14] SQR is such a conserved protein because SQR enhances energy conservation and synthesizes ATP when carbon sources are depleted, but the main incentive to conserve SQR is to detoxify sulfide.[10][14]

A 2021 study found that increased SQR levels were protective against hypoxia in squirrels and mice.[15]

References edit

  1. ^ Arieli B, Shahak Y, Taglicht D, Hauska G, Padan E (February 1994). "Purification and characterization of sulfide-quinone reductase, a novel enzyme driving anoxygenic photosynthesis in Oscillatoria limnetica". The Journal of Biological Chemistry. 269 (8): 5705–11. doi:10.1016/S0021-9258(17)37518-X. PMID 8119908.
  2. ^ Reinartz M, Tschäpe J, Brüser T, Trüper HG, Dahl C (July 1998). "Sulfide oxidation in the phototrophic sulfur bacterium Chromatium vinosum". Archives of Microbiology. 170 (1): 59–68. doi:10.1007/s002030050615. PMID 9639604. S2CID 38868444.
  3. ^ Nübel T, Klughammer C, Huber R, Hauska G, Schütz M (April 2000). "Sulfide:quinone oxidoreductase in membranes of the hyperthermophilic bacterium Aquifex aeolicus (VF5)". Archives of Microbiology. 173 (4): 233–44. doi:10.1007/s002030000135. PMID 10816041. S2CID 6412823.
  4. ^ Brito JA, Sousa FL, Stelter M, Bandeiras TM, Vonrhein C, Teixeira M, Pereira MM, Archer M (June 2009). "Structural and functional insights into sulfide:quinone oxidoreductase". Biochemistry. 48 (24): 5613–22. doi:10.1021/bi9003827. PMID 19438211.
  5. ^ Cherney MM, Zhang Y, Solomonson M, Weiner JH, James MN (April 2010). "Crystal structure of sulfide:quinone oxidoreductase from Acidithiobacillus ferrooxidans: insights into sulfidotrophic respiration and detoxification". Journal of Molecular Biology. 398 (2): 292–305. doi:10.1016/j.jmb.2010.03.018. PMID 20303979.
  6. ^ Marcia M, Langer JD, Parcej D, Vogel V, Peng G, Michel H (November 2010). "Characterizing a monotopic membrane enzyme. Biochemical, enzymatic and crystallization studies on Aquifex aeolicus sulfide:quinone oxidoreductase". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1798 (11): 2114–23. doi:10.1016/j.bbamem.2010.07.033. PMID 20691146.
  7. ^ a b "BRENDA - Information on EC 1.8.5.4 - bacterial sulfide:quinone reductase". www.brenda-enzymes.org. Retrieved 2020-10-17.
  8. ^ "BRENDA - Information on EC 1.8.5.8 - eukaryotic sulfide quinone oxidoreductase". www.brenda-enzymes.org. Retrieved 2020-10-17.
  9. ^ Brito, José A.; Sousa, Filipa L.; Stelter, Meike; Bandeiras, Tiago M.; Vonrhein, Clemens; Teixeira, Miguel; Pereira, Manuela M.; Archer, Margarida (2009-06-23). "Structural and Functional Insights into Sulfide:Quinone Oxidoreductase". Biochemistry. 48 (24): 5613–5622. doi:10.1021/bi9003827. ISSN 0006-2960. PMID 19438211.
  10. ^ a b c Marcia, Marco; Ermler, Ulrich; Peng, Guohong; Michel, Hartmut (2009-06-16). "The structure of Aquifex aeolicus sulfide:quinone oxidoreductase, a basis to understand sulfide detoxification and respiration". Proceedings of the National Academy of Sciences. 106 (24): 9625–9630. Bibcode:2009PNAS..106.9625M. doi:10.1073/pnas.0904165106. ISSN 0027-8424. PMC 2689314. PMID 19487671.
  11. ^ Marcia, Marco; Langer, Julian D.; Parcej, David; Vogel, Vitali; Peng, Guohong; Michel, Hartmut (2010-11-01). "Characterizing a monotopic membrane enzyme. Biochemical, enzymatic and crystallization studies on Aquifex aeolicus sulfide:quinone oxidoreductase". Biochimica et Biophysica Acta (BBA) - Biomembranes. 1798 (11): 2114–2123. doi:10.1016/j.bbamem.2010.07.033. ISSN 0005-2736. PMID 20691146.
  12. ^ a b c d van der Stel, Anne-Xander; Wösten, Marc M. S. M. (2019-07-30). "Regulation of Respiratory Pathways in Campylobacterota: A Review". Frontiers in Microbiology. 10: 1719. doi:10.3389/fmicb.2019.01719. ISSN 1664-302X. PMC 6682613. PMID 31417516.
  13. ^ a b c Nübel, Tobias; Klughammer, Christof; Huber, Robert; Hauska, Günter; Schütz, Michael (2000-04-01). "Sulfide:quinone oxidoreductase in membranes of the hyperthermophilic bacterium Aquifex aeolicus (VF5)". Archives of Microbiology. 173 (4): 233–244. doi:10.1007/s002030000135. ISSN 1432-072X. PMID 10816041. S2CID 6412823.
  14. ^ a b c d Kracke, Frauke; Vassilev, Igor; Krömer, Jens O. (2015-06-11). "Microbial electron transport and energy conservation – the foundation for optimizing bioelectrochemical systems". Frontiers in Microbiology. 6: 575. doi:10.3389/fmicb.2015.00575. ISSN 1664-302X. PMC 4463002. PMID 26124754.
  15. ^ "Serendipitous discovery could lead to treatment for strokes, cardiac arrest". medicalxpress.com. Retrieved 2021-05-26.

External links edit

January 01, 1970
sulfide, quinone, reductase, enzyme, with, systematic, name, sulfide, quinone, oxidoreductase, this, enzyme, catalyses, following, chemical, reactionidentifiersec, 4databasesintenzintenz, viewbrendabrenda, entryexpasynicezyme, viewkeggkegg, entrymetacycmetabol. Sulfide quinone reductase SQR EC 1 8 5 4 is an enzyme with systematic name sulfide quinone oxidoreductase 1 2 3 4 5 6 This enzyme catalyses the following chemical reactionSulfide quinone reductaseIdentifiersEC no 1 8 5 4DatabasesIntEnzIntEnz viewBRENDABRENDA entryExPASyNiceZyme viewKEGGKEGG entryMetaCycmetabolic pathwayPRIAMprofilePDB structuresRCSB PDB PDBe PDBsumSearchPMCarticlesPubMedarticlesNCBIproteins n HS n quinone displaystyle rightleftharpoons polysulfide n quinol SQR contains FAD Ubiquinone plastoquinone or menaquinone can act as acceptor in different species The Enzyme Commission EC number for SQR is 1 8 5 The number indicates that the protein is an oxidoreductase indicated by 1 The oxidoreductase reacts with a sulfur molecule sulfide in this case to donate electrons indicated by 8 The donated electrons are accepted by a quinone indicated by 5 7 Multiple sulfide quinone oxidoreductases are found in bacteria archaea and eukaryotes but the function highlighted in the EC numbers 1 8 5 are all constant except that the final digit with is 4 in bacteria and 8 in eukaryotic mitochondria 8 7 Contents 1 Crystalline structure 2 Reaction Pathway 3 Role in metabolism 4 References 5 External linksCrystalline structure editThe SQR in Aquifex aeolicus is composed of three subunits with a negatively charged hydrophilic side exposed to the periplasmic space and a hydrophobic region that integrates into the cell s plasma membrane The protein s active site is composed of an FAD cofactor covalently linked by a thioether bond to the enzyme On the si side of the FAD the sulfide reacts and donates its electrons to FAD while the re side of FAD is connected to a disulfide bridge and donates electrons to the quinone 2 3 The quinone is surrounded by Phe 385 and Ile 346 Both amino acids are located in the hydrophobic region of the plasma membrane and are conserved among all sulfide quinone oxidoreductases 9 Reaction Pathway editIn A aeolicus SQR is an integral monotopic protein so it penetrates into the hydrophobic region of the plasma membrane The SQR reaction takes place in two half reactions sulfide oxidation and quinone reduction The active site of SQR is composed of a region that interacts with the periplasmic space and sulfide connected by a FAD cofactor and a trisulfide bridge to a quinone FAD receives two electrons from sulfide and transfers the electrons one at time to the quinone The amino acids surrounding the quinone are all hydrophobic Also there is a highly conserved region of uncharged amino acids phenylalanine and isoleucine that surround the benzene ring of the quinone 10 SQR is a member of the flavoprotein disulfide reductase FDR superfamily FDRs are typically characterized as being dimeric or two subunit proteins but sulfide quinone oxidoreductase is a trimeric protein The main purpose of SQR is to detoxify sulfide Sulfide is a toxic chemical that inhibits enzymatic reactions especially those with metal cofactors Most notably sulfide inhibits cytochrome oxidase found in the electron transport chain SQR oxidizes sulfide and produces non toxic products 11 Role in metabolism editSQR is an integral protein that enters cells plasma membrane or inner mitochondrial membrane 12 The plasma membrane is the site of the electron transport chain for respiration 13 The electron transport chain depends on two factors 1 ability of a membrane to store an ion gradient 2 the ability of an organism to pump hydrogen ions against a gradient from low to high concentration 12 SQR enhances the formation of an ion gradient by donating two electrons to the quinone 13 Once the electrons are in the quinone they are transported to the quinone pool 12 The quinone pool is located inside the hydrophobic region of the plasma membrane and plays a role in transporting hydrogen ions to the periplasm From the quinone pool electrons travel to cytochrome c oxidase where oxygen is waiting as the final electron acceptor 12 13 Electrons from carbon sources react in a similar fashion to those in sulfide Two main differences separate the carbon pathway and the sulfur pathway 1 sulfur sulfide in this case skips glycolysis and the tricarboxylic acid cycle TCA while the carbon pathway requires both cycles to store electrons in NADHl 10 14 2 electrons from sulfide are donated to SQR while the electrons from NADH are donated to the NADH quinone oxidoreductase 14 In both cases the electrons are shuttled to the quinone pool then to cytochrome c oxidase where the final electron acceptor is waiting 14 SQR is such a conserved protein because SQR enhances energy conservation and synthesizes ATP when carbon sources are depleted but the main incentive to conserve SQR is to detoxify sulfide 10 14 A 2021 study found that increased SQR levels were protective against hypoxia in squirrels and mice 15 References edit Arieli B Shahak Y Taglicht D Hauska G Padan E February 1994 Purification and characterization of sulfide quinone reductase a novel enzyme driving anoxygenic photosynthesis in Oscillatoria limnetica The Journal of Biological Chemistry 269 8 5705 11 doi 10 1016 S0021 9258 17 37518 X PMID 8119908 Reinartz M Tschape J Bruser T Truper HG Dahl C July 1998 Sulfide oxidation in the phototrophic sulfur bacterium Chromatium vinosum Archives of Microbiology 170 1 59 68 doi 10 1007 s002030050615 PMID 9639604 S2CID 38868444 Nubel T Klughammer C Huber R Hauska G Schutz M April 2000 Sulfide quinone oxidoreductase in membranes of the hyperthermophilic bacterium Aquifex aeolicus VF5 Archives of Microbiology 173 4 233 44 doi 10 1007 s002030000135 PMID 10816041 S2CID 6412823 Brito JA Sousa FL Stelter M Bandeiras TM Vonrhein C Teixeira M Pereira MM Archer M June 2009 Structural and functional insights into sulfide quinone oxidoreductase Biochemistry 48 24 5613 22 doi 10 1021 bi9003827 PMID 19438211 Cherney MM Zhang Y Solomonson M Weiner JH James MN April 2010 Crystal structure of sulfide quinone oxidoreductase from Acidithiobacillus ferrooxidans insights into sulfidotrophic respiration and detoxification Journal of Molecular Biology 398 2 292 305 doi 10 1016 j jmb 2010 03 018 PMID 20303979 Marcia M Langer JD Parcej D Vogel V Peng G Michel H November 2010 Characterizing a monotopic membrane enzyme Biochemical enzymatic and crystallization studies on Aquifex aeolicus sulfide quinone oxidoreductase Biochimica et Biophysica Acta BBA Biomembranes 1798 11 2114 23 doi 10 1016 j bbamem 2010 07 033 PMID 20691146 a b BRENDA Information on EC 1 8 5 4 bacterial sulfide quinone reductase www brenda enzymes org Retrieved 2020 10 17 BRENDA Information on EC 1 8 5 8 eukaryotic sulfide quinone oxidoreductase www brenda enzymes org Retrieved 2020 10 17 Brito Jose A Sousa Filipa L Stelter Meike Bandeiras Tiago M Vonrhein Clemens Teixeira Miguel Pereira Manuela M Archer Margarida 2009 06 23 Structural and Functional Insights into Sulfide Quinone Oxidoreductase Biochemistry 48 24 5613 5622 doi 10 1021 bi9003827 ISSN 0006 2960 PMID 19438211 a b c Marcia Marco Ermler Ulrich Peng Guohong Michel Hartmut 2009 06 16 The structure of Aquifex aeolicus sulfide quinone oxidoreductase a basis to understand sulfide detoxification and respiration Proceedings of the National Academy of Sciences 106 24 9625 9630 Bibcode 2009PNAS 106 9625M doi 10 1073 pnas 0904165106 ISSN 0027 8424 PMC 2689314 PMID 19487671 Marcia Marco Langer Julian D Parcej David Vogel Vitali Peng Guohong Michel Hartmut 2010 11 01 Characterizing a monotopic membrane enzyme Biochemical enzymatic and crystallization studies on Aquifex aeolicus sulfide quinone oxidoreductase Biochimica et Biophysica Acta BBA Biomembranes 1798 11 2114 2123 doi 10 1016 j bbamem 2010 07 033 ISSN 0005 2736 PMID 20691146 a b c d van der Stel Anne Xander Wosten Marc M S M 2019 07 30 Regulation of Respiratory Pathways in Campylobacterota A Review Frontiers in Microbiology 10 1719 doi 10 3389 fmicb 2019 01719 ISSN 1664 302X PMC 6682613 PMID 31417516 a b c Nubel Tobias Klughammer Christof Huber Robert Hauska Gunter Schutz Michael 2000 04 01 Sulfide quinone oxidoreductase in membranes of the hyperthermophilic bacterium Aquifex aeolicus VF5 Archives of Microbiology 173 4 233 244 doi 10 1007 s002030000135 ISSN 1432 072X PMID 10816041 S2CID 6412823 a b c d Kracke Frauke Vassilev Igor Kromer Jens O 2015 06 11 Microbial electron transport and energy conservation the foundation for optimizing bioelectrochemical systems Frontiers in Microbiology 6 575 doi 10 3389 fmicb 2015 00575 ISSN 1664 302X PMC 4463002 PMID 26124754 Serendipitous discovery could lead to treatment for strokes cardiac arrest medicalxpress com Retrieved 2021 05 26 External links editSulfide quinone reductase at the U S National Library of Medicine Medical Subject Headings MeSH Portal nbsp Biology Retrieved from https en wikipedia org w index php title Sulfide quinone reductase amp oldid 1172361834, wikipedia, wiki, book, books, library,

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