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| | ==Crystal structure of nitrophorin 7 E27V mutant from Rhodnius prolixus with imidazole== | | ==Crystal structure of nitrophorin 7 E27V mutant from Rhodnius prolixus with imidazole== |
| - | <StructureSection load='5m6k' size='340' side='right' caption='[[5m6k]], [[Resolution|resolution]] 1.60Å' scene=''> | + | <StructureSection load='5m6k' size='340' side='right'caption='[[5m6k]], [[Resolution|resolution]] 1.60Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[5m6k]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5M6K OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5M6K FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[5m6k]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5M6K OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5M6K FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=IMD:IMIDAZOLE'>IMD</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]] 1.6Å</td></tr> |
| - | <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Nitrite_dismutase Nitrite dismutase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.7.6.1 1.7.6.1] </span></td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene>, <scene name='pdbligand=IMD:IMIDAZOLE'>IMD</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=5m6k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5m6k OCA], [http://pdbe.org/5m6k PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5m6k RCSB], [http://www.ebi.ac.uk/pdbsum/5m6k PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5m6k ProSAT]</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=5m6k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5m6k OCA], [https://pdbe.org/5m6k PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5m6k RCSB], [https://www.ebi.ac.uk/pdbsum/5m6k PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5m6k ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/NP7_RHOPR NP7_RHOPR]] Converts nitrite as the sole substrate to form nitric oxide gas (NO). NO(2-) serves both as an electron donor and as an electron acceptor. Binds to negatively charged cell surfaces of activated platelets; binds to L-a-phosphatidyl-L-serine (PS)-bearing phospholipid membranes. Once bound on an activated platelet, NP7 releases its stored nitric oxide gas (NO) into the victim's tissues while feeding, resulting in vasodilation and inhibition of platelet aggregation. Also acts as an anticoagulant by blocking coagulation-factor binding sites. Has antihistamine activity; binds histamine with high affinity.<ref>PMID:15170336</ref> <ref>PMID:15598503</ref> <ref>PMID:17428677</ref> <ref>PMID:17958381</ref> <ref>PMID:19655755</ref> | + | [https://www.uniprot.org/uniprot/NP7_RHOPR NP7_RHOPR] Converts nitrite as the sole substrate to form nitric oxide gas (NO). NO(2-) serves both as an electron donor and as an electron acceptor. Binds to negatively charged cell surfaces of activated platelets; binds to L-a-phosphatidyl-L-serine (PS)-bearing phospholipid membranes. Once bound on an activated platelet, NP7 releases its stored nitric oxide gas (NO) into the victim's tissues while feeding, resulting in vasodilation and inhibition of platelet aggregation. Also acts as an anticoagulant by blocking coagulation-factor binding sites. Has antihistamine activity; binds histamine with high affinity.<ref>PMID:15170336</ref> <ref>PMID:15598503</ref> <ref>PMID:17428677</ref> <ref>PMID:17958381</ref> <ref>PMID:19655755</ref> |
| | + | <div style="background-color:#fffaf0;"> |
| | + | == Publication Abstract from PubMed == |
| | + | Nitrophorins (NP) 1-7 are NO-carrying heme proteins found in the saliva of the blood-sucking insect Rhodnius prolixus. The isoform NP7 displays peculiar properties, such as an abnormally high isoelectric point, the ability to bind negatively charged membranes, and a strong pH sensitivity of NO affinity. A unique trait of NP7 is the presence of Glu in position 27, which is occupied by Val in other NPs. Glu27 appears to be important for tuning the heme properties, but its influence on the pH-dependent NO release mechanism, which is assisted by a conformational change in the AB loop, remains unexplored. Here, in order to gain insight into the functional role of Glu27, we examine the effect of Glu27 --> Val and Glu27 --> Gln mutations on the ligand binding kinetics using CO as a model. The results reveal that annihilation of the negative charge of Glu27 upon mutation reduces the pH sensitivity of the ligand binding rate, a process that in turn depends on the ionization of Asp32. We propose that Glu27 exerts a through-space electrostatic action on Asp32, which shifts the pKa of the latter amino acid towards more acidic values thus reducing the pH sensitivity of the transition between open and closed states. |
| | + | |
| | + | Electrostatic Tuning of the Ligand Binding Mechanism by Glu27 in Nitrophorin 7.,Abbruzzetti S, Allegri A, Bidon-Chanal A, Ogata H, Soavi G, Cerullo G, Bruno S, Montali C, Luque FJ, Viappiani C Sci Rep. 2018 Jul 18;8(1):10855. doi: 10.1038/s41598-018-29182-3. PMID:30022039<ref>PMID:30022039</ref> |
| | + | |
| | + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> |
| | + | </div> |
| | + | <div class="pdbe-citations 5m6k" style="background-color:#fffaf0;"></div> |
| | + | |
| | + | ==See Also== |
| | + | *[[Nitrophorin|Nitrophorin]] |
| | == References == | | == References == |
| | <references/> | | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Nitrite dismutase]] | + | [[Category: Large Structures]] |
| - | [[Category: Ogata, H]] | + | [[Category: Rhodnius prolixus]] |
| - | [[Category: Heme protein]] | + | [[Category: Ogata H]] |
| - | [[Category: No transporter]]
| + | |
| - | [[Category: Oxidoreductase]]
| + | |
| Structural highlights
Function
NP7_RHOPR Converts nitrite as the sole substrate to form nitric oxide gas (NO). NO(2-) serves both as an electron donor and as an electron acceptor. Binds to negatively charged cell surfaces of activated platelets; binds to L-a-phosphatidyl-L-serine (PS)-bearing phospholipid membranes. Once bound on an activated platelet, NP7 releases its stored nitric oxide gas (NO) into the victim's tissues while feeding, resulting in vasodilation and inhibition of platelet aggregation. Also acts as an anticoagulant by blocking coagulation-factor binding sites. Has antihistamine activity; binds histamine with high affinity.[1] [2] [3] [4] [5]
Publication Abstract from PubMed
Nitrophorins (NP) 1-7 are NO-carrying heme proteins found in the saliva of the blood-sucking insect Rhodnius prolixus. The isoform NP7 displays peculiar properties, such as an abnormally high isoelectric point, the ability to bind negatively charged membranes, and a strong pH sensitivity of NO affinity. A unique trait of NP7 is the presence of Glu in position 27, which is occupied by Val in other NPs. Glu27 appears to be important for tuning the heme properties, but its influence on the pH-dependent NO release mechanism, which is assisted by a conformational change in the AB loop, remains unexplored. Here, in order to gain insight into the functional role of Glu27, we examine the effect of Glu27 --> Val and Glu27 --> Gln mutations on the ligand binding kinetics using CO as a model. The results reveal that annihilation of the negative charge of Glu27 upon mutation reduces the pH sensitivity of the ligand binding rate, a process that in turn depends on the ionization of Asp32. We propose that Glu27 exerts a through-space electrostatic action on Asp32, which shifts the pKa of the latter amino acid towards more acidic values thus reducing the pH sensitivity of the transition between open and closed states.
Electrostatic Tuning of the Ligand Binding Mechanism by Glu27 in Nitrophorin 7.,Abbruzzetti S, Allegri A, Bidon-Chanal A, Ogata H, Soavi G, Cerullo G, Bruno S, Montali C, Luque FJ, Viappiani C Sci Rep. 2018 Jul 18;8(1):10855. doi: 10.1038/s41598-018-29182-3. PMID:30022039[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Andersen JF, Gudderra NP, Francischetti IM, Valenzuela JG, Ribeiro JM. Recognition of anionic phospholipid membranes by an antihemostatic protein from a blood-feeding insect. Biochemistry. 2004 Jun 8;43(22):6987-94. PMID:15170336 doi:http://dx.doi.org/10.1021/bi049655t
- ↑ Walker FA. Nitric oxide interaction with insect nitrophorins and thoughts on the electron configuration of the {FeNO}6 complex. J Inorg Biochem. 2005 Jan;99(1):216-36. PMID:15598503 doi:http://dx.doi.org/10.1016/j.jinorgbio.2004.10.009
- ↑ Knipp M, Zhang H, Berry RE, Walker FA. Overexpression in Escherichia coli and functional reconstitution of the liposome binding ferriheme protein nitrophorin 7 from the bloodsucking bug Rhodnius prolixus. Protein Expr Purif. 2007 Jul;54(1):183-91. Epub 2007 Mar 7. PMID:17428677 doi:http://dx.doi.org/10.1016/j.pep.2007.02.017
- ↑ Knipp M, Yang F, Berry RE, Zhang H, Shokhirev MN, Walker FA. Spectroscopic and functional characterization of nitrophorin 7 from the blood-feeding insect Rhodnius prolixus reveals an important role of its isoform-specific N-terminus for proper protein function. Biochemistry. 2007 Nov 20;46(46):13254-68. Epub 2007 Oct 24. PMID:17958381 doi:http://dx.doi.org/10.1021/bi7014986
- ↑ He C, Knipp M. Formation of nitric oxide from nitrite by the ferriheme b protein nitrophorin 7. J Am Chem Soc. 2009 Sep 2;131(34):12042-3. doi: 10.1021/ja9040362. PMID:19655755 doi:http://dx.doi.org/10.1021/ja9040362
- ↑ Abbruzzetti S, Allegri A, Bidon-Chanal A, Ogata H, Soavi G, Cerullo G, Bruno S, Montali C, Luque FJ, Viappiani C. Electrostatic Tuning of the Ligand Binding Mechanism by Glu27 in Nitrophorin 7. Sci Rep. 2018 Jul 18;8(1):10855. doi: 10.1038/s41598-018-29182-3. PMID:30022039 doi:http://dx.doi.org/10.1038/s41598-018-29182-3
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