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| | ==Structure of the free TvNiRb form of Thioalkalivibrio nitratireducens cytochrome c nitrite reductase== | | ==Structure of the free TvNiRb form of Thioalkalivibrio nitratireducens cytochrome c nitrite reductase== |
| - | <StructureSection load='3uu9' size='340' side='right' caption='[[3uu9]], [[Resolution|resolution]] 2.20Å' scene=''> | + | <StructureSection load='3uu9' size='340' side='right'caption='[[3uu9]], [[Resolution|resolution]] 2.20Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[3uu9]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Thioalkalivibrio_nitratireducens Thioalkalivibrio nitratireducens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3UU9 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3UU9 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[3uu9]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Thioalkalivibrio_nitratireducens Thioalkalivibrio nitratireducens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3UU9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3UU9 FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=HEC:HEME+C'>HEC</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.2Å</td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3lgq|3lgq]], [[3rkh|3rkh]]</td></tr>
| + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=HEC:HEME+C'>HEC</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3uu9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3uu9 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3uu9 RCSB], [http://www.ebi.ac.uk/pdbsum/3uu9 PDBsum]</span></td></tr> | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3uu9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3uu9 OCA], [https://pdbe.org/3uu9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3uu9 RCSB], [https://www.ebi.ac.uk/pdbsum/3uu9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3uu9 ProSAT]</span></td></tr> |
| | </table> | | </table> |
| - | <div style="background-color:#fffaf0;">
| + | == Function == |
| - | == Publication Abstract from PubMed == | + | [https://www.uniprot.org/uniprot/NIR_THIND NIR_THIND] Catalyzes the reduction of nitrite to ammonia, consuming six electrons in the process (PubMed:16500161, PubMed:22281743). Has very low activity toward hydroxylamine (PubMed:16500161). Has even lower activity toward sulfite (PubMed:16500161, PubMed:22281743). Sulfite reductase activity is maximal at neutral pH (PubMed:20944237).<ref>PMID:16500161</ref> <ref>PMID:20944237</ref> <ref>PMID:22281743</ref> |
| - | Octahaem cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR), like the previously characterized pentahaem nitrite reductases (NrfAs), catalyzes the six-electron reductions of nitrite to ammonia and of sulfite to sulfide. The active site of both TvNiR and NrfAs is formed by the lysine-coordinated haem and His, Tyr and Arg residues. The distinguishing structural feature of TvNiR is the presence of a covalent bond between the CE2 atom of the catalytic Tyr303 and the S atom of Cys305, which might be responsible for the higher nitrite reductase activity of TvNiR compared with NrfAs. In the present study, a new modified form of the enzyme (TvNiRb) that contains an additional covalent bond between Tyr303 CE1 and Gln360 CG is reported. Structures of TvNiRb in complexes with phosphate (1.45 A resolution) and sulfite (1.8 A resolution), the structure of TvNiR in a complex with nitrite (1.83 A resolution) and several additional structures were determined. The formation of the second covalent bond by Tyr303 leads to a decrease in both the nitrite and sulfite reductase activities of the enzyme. Tyr303 is located at the exit from the putative proton-transport channel to the active site, which is absent in NrfAs. This is an additional argument in favour of the involvement of Tyr303 as a proton donor in catalysis. The changes in the activity of cytochrome c nitrite reductases owing to the formation of Tyr-Cys and Tyr-Gln bonds may be associated with changes in the pK(a) value of the catalytic tyrosine.
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| - | Covalent modifications of the catalytic tyrosine in octahaem cytochrome c nitrite reductase and their effect on the enzyme activity.,Trofimov AA, Polyakov KM, Tikhonova TV, Tikhonov AV, Safonova TN, Boyko KM, Dorovatovskii PV, Popov VO Acta Crystallogr D Biol Crystallogr. 2012 Feb;68(Pt 2):144-53. Epub 2012, Jan 13. PMID:22281743<ref>PMID:22281743</ref>
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| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| - | </div> | + | |
| | | | |
| | ==See Also== | | ==See Also== |
| - | *[[Nitric reductase|Nitric reductase]] | + | *[[Cytochrome c nitrite reductase|Cytochrome c nitrite reductase]] |
| | == References == | | == References == |
| | <references/> | | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| | + | [[Category: Large Structures]] |
| | [[Category: Thioalkalivibrio nitratireducens]] | | [[Category: Thioalkalivibrio nitratireducens]] |
| - | [[Category: Dorovatovskii, P V]] | + | [[Category: Dorovatovskii PV]] |
| - | [[Category: Polyakov, K M]] | + | [[Category: Polyakov KM]] |
| - | [[Category: Popov, V O]] | + | [[Category: Popov VO]] |
| - | [[Category: Tikhonov, A V]] | + | [[Category: Tikhonov AV]] |
| - | [[Category: Tikhonova, T V]] | + | [[Category: Tikhonova TV]] |
| - | [[Category: Trofimov, A A]] | + | [[Category: Trofimov AA]] |
| - | [[Category: Oxidoreductase]]
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| Structural highlights
Function
NIR_THIND Catalyzes the reduction of nitrite to ammonia, consuming six electrons in the process (PubMed:16500161, PubMed:22281743). Has very low activity toward hydroxylamine (PubMed:16500161). Has even lower activity toward sulfite (PubMed:16500161, PubMed:22281743). Sulfite reductase activity is maximal at neutral pH (PubMed:20944237).[1] [2] [3]
See Also
References
- ↑ Tikhonova TV, Slutsky A, Antipov AN, Boyko KM, Polyakov KM, Sorokin DY, Zvyagilskaya RA, Popov VO. Molecular and catalytic properties of a novel cytochrome c nitrite reductase from nitrate-reducing haloalkaliphilic sulfur-oxidizing bacterium Thioalkalivibrio nitratireducens. Biochim Biophys Acta. 2006 Apr;1764(4):715-23. Epub 2006 Feb 9. PMID:16500161 doi:http://dx.doi.org/10.1016/j.bbapap.2005.12.021
- ↑ Trofimov AA, Polyakov KM, Boyko KM, Tikhonova TV, Safonova TN, Tikhonov AV, Popov AN, Popov VO. Structures of complexes of octahaem cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens with sulfite and cyanide. Acta Crystallogr D Biol Crystallogr. 2010 Oct;66(Pt 10):1043-7. Epub 2010, Sep 18. PMID:20944237 doi:10.1107/S0907444910031665
- ↑ Trofimov AA, Polyakov KM, Tikhonova TV, Tikhonov AV, Safonova TN, Boyko KM, Dorovatovskii PV, Popov VO. Covalent modifications of the catalytic tyrosine in octahaem cytochrome c nitrite reductase and their effect on the enzyme activity. Acta Crystallogr D Biol Crystallogr. 2012 Feb;68(Pt 2):144-53. Epub 2012, Jan 13. PMID:22281743 doi:10.1107/S0907444911052632
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