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==Structure of the Thioalkalivibrio nitratireducens cytochrome c nitrite reductase with a covalent bond between the CE1 atom of Tyr303 and the CG atom of Gln360 (TvNiRb)== | ==Structure of the Thioalkalivibrio nitratireducens cytochrome c nitrite reductase with a covalent bond between the CE1 atom of Tyr303 and the CG atom of Gln360 (TvNiRb)== | ||
<StructureSection load='3sce' size='340' side='right' caption='[[3sce]], [[Resolution|resolution]] 1.45Å' scene=''> | <StructureSection load='3sce' size='340' side='right' caption='[[3sce]], [[Resolution|resolution]] 1.45Å' scene=''> | ||
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</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>, <scene name='pdbligand=PG6:1-(2-METHOXY-ETHOXY)-2-{2-[2-(2-METHOXY-ETHOXY]-ETHOXY}-ETHANE'>PG6</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></td></tr> | </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>, <scene name='pdbligand=PG6:1-(2-METHOXY-ETHOXY)-2-{2-[2-(2-METHOXY-ETHOXY]-ETHOXY}-ETHANE'>PG6</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></td></tr> | ||
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2ot4|2ot4]]</td></tr> | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[2ot4|2ot4]]</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=3sce FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3sce OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3sce RCSB], [http://www.ebi.ac.uk/pdbsum/3sce PDBsum]</span></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=3sce FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3sce OCA], [http://pdbe.org/3sce PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3sce RCSB], [http://www.ebi.ac.uk/pdbsum/3sce PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3sce ProSAT]</span></td></tr> | ||
</table> | </table> | ||
== Function == | == Function == | ||
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | ||
</div> | </div> | ||
<div class="pdbe-citations 3sce" style="background-color:#fffaf0;"></div> | |||
==See Also== | ==See Also== | ||
Revision as of 23:00, 4 August 2016
Structure of the Thioalkalivibrio nitratireducens cytochrome c nitrite reductase with a covalent bond between the CE1 atom of Tyr303 and the CG atom of Gln360 (TvNiRb)Structure of the Thioalkalivibrio nitratireducens cytochrome c nitrite reductase with a covalent bond between the CE1 atom of Tyr303 and the CG atom of Gln360 (TvNiRb)
Structural highlights
Function[Q5F2I3_9GAMM] Plays a role in nitrite reduction (By similarity).[SAAS:SAAS003321_004_001592] Publication Abstract from PubMedOctahaem 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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