1ntf
From Proteopedia
(New page: 200px<br /><applet load="1ntf" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ntf, resolution 1.80Å" /> '''Crystal Structure of...) |
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| - | [[Image:1ntf.gif|left|200px]]<br /><applet load="1ntf" size=" | + | [[Image:1ntf.gif|left|200px]]<br /><applet load="1ntf" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ntf, resolution 1.80Å" /> | caption="1ntf, resolution 1.80Å" /> | ||
'''Crystal Structure of Cimex Nitrophorin'''<br /> | '''Crystal Structure of Cimex Nitrophorin'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to | + | Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to induce vasodilation and inhibit blood coagulation. We have expressed, characterized, and determined the crystal structure of the Cimex lectularius (bedbug) nitrophorin, the protein responsible for NO storage and delivery, to understand how the insect successfully handles this reactive molecule. Surprisingly, NO binds not only to the ferric nitrophorin heme, but it can also be stored as an S-nitroso (SNO) conjugate of the proximal heme cysteine (Cys-60) when present at higher concentrations. EPR- and UV-visible spectroscopies, and a crystallographic structure determination to 1.75-A resolution, reveal SNO formation to proceed with reduction of the heme iron, yielding an Fe-NO complex. Stopped-flow kinetic measurements indicate that an ordered reaction mechanism takes place: initial NO binding occurs at the ferric heme and is followed by heme reduction, Cys-60 release from the heme iron, and SNO formation. Release of NO occurs through a reversal of these steps. These data provide, to our knowledge, the first view of reversible metal-assisted SNO formation in a protein and suggest a mechanism for its role in NO release from ferrous heme. This mechanism and Cimex nitrophorin structure are completely unlike those of the nitrophorins from Rhodnius prolixus, where NO protection is provided by a large conformational change that buries the heme nitrosyl complex, highlighting the remarkable evolution of proteins that assist insects in bloodfeeding. |
==About this Structure== | ==About this Structure== | ||
| - | 1NTF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cimex_lectularius Cimex lectularius] with HEM as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1NTF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cimex_lectularius Cimex lectularius] with <scene name='pdbligand=HEM:'>HEM</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NTF OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Cimex lectularius]] | [[Category: Cimex lectularius]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Andersen, J | + | [[Category: Andersen, J F.]] |
| - | [[Category: Maes, E | + | [[Category: Maes, E M.]] |
| - | [[Category: Montfort, W | + | [[Category: Montfort, W R.]] |
| - | [[Category: Valenzuela, J | + | [[Category: Valenzuela, J G.]] |
| - | [[Category: Walker, F | + | [[Category: Walker, F A.]] |
[[Category: Weichsel, A.]] | [[Category: Weichsel, A.]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
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[[Category: no carrier]] | [[Category: no carrier]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:09:48 2008'' |
Revision as of 12:09, 21 February 2008
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Crystal Structure of Cimex Nitrophorin
Overview
Certain bloodsucking insects deliver nitric oxide (NO) while feeding, to induce vasodilation and inhibit blood coagulation. We have expressed, characterized, and determined the crystal structure of the Cimex lectularius (bedbug) nitrophorin, the protein responsible for NO storage and delivery, to understand how the insect successfully handles this reactive molecule. Surprisingly, NO binds not only to the ferric nitrophorin heme, but it can also be stored as an S-nitroso (SNO) conjugate of the proximal heme cysteine (Cys-60) when present at higher concentrations. EPR- and UV-visible spectroscopies, and a crystallographic structure determination to 1.75-A resolution, reveal SNO formation to proceed with reduction of the heme iron, yielding an Fe-NO complex. Stopped-flow kinetic measurements indicate that an ordered reaction mechanism takes place: initial NO binding occurs at the ferric heme and is followed by heme reduction, Cys-60 release from the heme iron, and SNO formation. Release of NO occurs through a reversal of these steps. These data provide, to our knowledge, the first view of reversible metal-assisted SNO formation in a protein and suggest a mechanism for its role in NO release from ferrous heme. This mechanism and Cimex nitrophorin structure are completely unlike those of the nitrophorins from Rhodnius prolixus, where NO protection is provided by a large conformational change that buries the heme nitrosyl complex, highlighting the remarkable evolution of proteins that assist insects in bloodfeeding.
About this Structure
1NTF is a Single protein structure of sequence from Cimex lectularius with as ligand. Full crystallographic information is available from OCA.
Reference
Heme-assisted S-nitrosation of a proximal thiolate in a nitric oxide transport protein., Weichsel A, Maes EM, Andersen JF, Valenzuela JG, Shokhireva TKh, Walker FA, Montfort WR, Proc Natl Acad Sci U S A. 2005 Jan 18;102(3):594-9. Epub 2005 Jan 6. PMID:15637157
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