1x8p: Difference between revisions
New page: left|200px<br /><applet load="1x8p" size="450" color="white" frame="true" align="right" spinBox="true" caption="1x8p, resolution 0.85Å" /> '''0.85 A Crystal Struc... |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1x8p.gif|left|200px]]<br /><applet load="1x8p" size=" | [[Image:1x8p.gif|left|200px]]<br /><applet load="1x8p" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1x8p, resolution 0.85Å" /> | caption="1x8p, resolution 0.85Å" /> | ||
'''0.85 A Crystal Structure Of Nitrophorin 4 From Rhodnius Prolixus Complexed With Ammonia at pH 7.4'''<br /> | '''0.85 A Crystal Structure Of Nitrophorin 4 From Rhodnius Prolixus Complexed With Ammonia at pH 7.4'''<br /> | ||
==Overview== | ==Overview== | ||
The blood-sucking insect Rhodnius prolixus uses nitrophorin 4, a heme | The blood-sucking insect Rhodnius prolixus uses nitrophorin 4, a heme protein, to deliver nitric oxide (NO) to a victim, causing vasodilation and improved feeding. Binding of NO occurs at a ferric heme and is modulated by pH. NO binding at lower pH induces a large conformational change involving loops A-B and G-H that leads to distal pocket desolvation and protection of the nitrosyl heme complex. We have determined the crystal structures of Rhodnius nitrophorin 4 to ultrahigh resolution in four functional states: +/-NO at pH = 7.4 and +/-NO at pH = 5.6. The structure with NO at pH 7.4 (1.08 A) is newly determined while the other complexes have been modeled to resolutions much greater than previously reported (1.0-0.85 A). The ultrahigh resolution allowed us to resolve multiple conformers in binding-site loops, leading to a detailed description of the dynamics involved with storing NO in the insect salivary gland at low pH, and releasing NO in response to the increased pH of a victim's tissue. Strikingly, features for both the "open" and "closed" conformers exist under all conditions, suggesting that the flexible loops can transition with relative ease between conformational states. Yet, release of NO from rNP4 is much slower than found for other ferric heme proteins. The structures suggest that highly mobile loops can limit diffusion of diatomic molecules into and out of a protein cavity, a result with implications for the role of protein dynamics in function. | ||
==About this Structure== | ==About this Structure== | ||
1X8P is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus] with HEM and NH3 as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1X8P is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rhodnius_prolixus Rhodnius prolixus] with <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=NH3:'>NH3</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1X8P OCA]. | ||
==Reference== | ==Reference== | ||
| Line 13: | Line 13: | ||
[[Category: Rhodnius prolixus]] | [[Category: Rhodnius prolixus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Kondrashov, D | [[Category: Kondrashov, D A.]] | ||
[[Category: Montfort, W | [[Category: Montfort, W R.]] | ||
[[Category: Roberts, S | [[Category: Roberts, S A.]] | ||
[[Category: Weichsel, A.]] | [[Category: Weichsel, A.]] | ||
[[Category: HEM]] | [[Category: HEM]] | ||
| Line 21: | Line 21: | ||
[[Category: lipocalin; beta barrel; ferric heme]] | [[Category: lipocalin; beta barrel; ferric heme]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:52:07 2008'' | ||
Revision as of 16:52, 21 February 2008
|
0.85 A Crystal Structure Of Nitrophorin 4 From Rhodnius Prolixus Complexed With Ammonia at pH 7.4
OverviewOverview
The blood-sucking insect Rhodnius prolixus uses nitrophorin 4, a heme protein, to deliver nitric oxide (NO) to a victim, causing vasodilation and improved feeding. Binding of NO occurs at a ferric heme and is modulated by pH. NO binding at lower pH induces a large conformational change involving loops A-B and G-H that leads to distal pocket desolvation and protection of the nitrosyl heme complex. We have determined the crystal structures of Rhodnius nitrophorin 4 to ultrahigh resolution in four functional states: +/-NO at pH = 7.4 and +/-NO at pH = 5.6. The structure with NO at pH 7.4 (1.08 A) is newly determined while the other complexes have been modeled to resolutions much greater than previously reported (1.0-0.85 A). The ultrahigh resolution allowed us to resolve multiple conformers in binding-site loops, leading to a detailed description of the dynamics involved with storing NO in the insect salivary gland at low pH, and releasing NO in response to the increased pH of a victim's tissue. Strikingly, features for both the "open" and "closed" conformers exist under all conditions, suggesting that the flexible loops can transition with relative ease between conformational states. Yet, release of NO from rNP4 is much slower than found for other ferric heme proteins. The structures suggest that highly mobile loops can limit diffusion of diatomic molecules into and out of a protein cavity, a result with implications for the role of protein dynamics in function.
About this StructureAbout this Structure
1X8P is a Single protein structure of sequence from Rhodnius prolixus with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Protein functional cycle viewed at atomic resolution: conformational change and mobility in nitrophorin 4 as a function of pH and NO binding., Kondrashov DA, Roberts SA, Weichsel A, Montfort WR, Biochemistry. 2004 Nov 2;43(43):13637-47. PMID:15504026
Page seeded by OCA on Thu Feb 21 15:52:07 2008