2b5k
From Proteopedia
(New page: 200px<br /><applet load="2b5k" size="450" color="white" frame="true" align="right" spinBox="true" caption="2b5k" /> '''PV5 NMR solution structure in DPC micelles''...) |
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| - | [[Image:2b5k.gif|left|200px]]<br /><applet load="2b5k" size=" | + | [[Image:2b5k.gif|left|200px]]<br /><applet load="2b5k" size="350" color="white" frame="true" align="right" spinBox="true" |
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'''PV5 NMR solution structure in DPC micelles'''<br /> | '''PV5 NMR solution structure in DPC micelles'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The horseshoe crab cationic antimicrobial peptide polyphemusin I is highly | + | The horseshoe crab cationic antimicrobial peptide polyphemusin I is highly active in vitro but not protective in mouse models of bacterial and LPS challenge, while a synthetic polyphemusin variant, PV5, was previously shown to be protective in vivo. In this study, we investigated the interaction of these peptides with lipid membranes in an effort to propose a mechanism of interaction. The solution structure of PV5 was determined by proton NMR in the absence and presence of dodecylphosphocholine (DPC) micelles. Like polyphemusin I, PV5 is a beta-hairpin but appeared less amphipathic in solution. Upon association with DPC micelles, PV5 underwent side chain rearrangements which resulted in an increased amphipathic conformation. Using fluorescence spectroscopy, both peptides were found to have limited affinity for neutral vesicles composed of phosphatidylcholine (PC). Incorporation of 25 mol % cholesterol or phosphatidylethanolamine into PC vesicles produced little change in the partitioning of either peptide. Incorporation of 25 mol % phosphatidylglycerol (PG) into PC vesicles, a simple prokaryotic model, resulted in a large increase in the affinity for both peptides, but the partition coefficient for PV5 was almost twice that of polyphemusin I. Differential scanning calorimetry studies supported the partitioning data and demonstrated that neither peptide interacted readily with neutral PC vesicles. Both peptides showed affinity for negatively charged membranes incorporating PG. The affinity of PV5 was much greater as the pretransition peak was absent at low peptide to lipid ratios (1:400) and the reduction in enthalpy of the main transition was greater than that produced by polyphemusin I. Both peptides decreased the lamellar to inverted hexagonal phase transition temperature of PE indicating the induction of negative curvature strain. These results, combined with previous findings that polyphemusin I promotes lipid flip-flop but does not induce significant vesicle leakage, ruled out the torroidal pore and carpet mechanisms of antimicrobial action for these polyphemusins. |
==About this Structure== | ==About this Structure== | ||
| - | 2B5K is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/ ] with NH2 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 2B5K is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/ ] with <scene name='pdbligand=NH2:'>NH2</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2B5K OCA]. |
==Reference== | ==Reference== | ||
Solution structure and interaction of the antimicrobial polyphemusins with lipid membranes., Powers JP, Tan A, Ramamoorthy A, Hancock RE, Biochemistry. 2005 Nov 29;44(47):15504-13. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16300399 16300399] | Solution structure and interaction of the antimicrobial polyphemusins with lipid membranes., Powers JP, Tan A, Ramamoorthy A, Hancock RE, Biochemistry. 2005 Nov 29;44(47):15504-13. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16300399 16300399] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Hancock, R | + | [[Category: Hancock, R E.W.]] |
| - | [[Category: Powers, J | + | [[Category: Powers, J P.S.]] |
[[Category: Ramamoorthy, A.]] | [[Category: Ramamoorthy, A.]] | ||
[[Category: Tan, A.]] | [[Category: Tan, A.]] | ||
| Line 19: | Line 19: | ||
[[Category: pv5; polyphemusin variant; beta hairpin; disulfide bridge; antimicrobial peptide]] | [[Category: pv5; polyphemusin variant; beta hairpin; disulfide bridge; antimicrobial peptide]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:34:25 2008'' |
Revision as of 14:34, 21 February 2008
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PV5 NMR solution structure in DPC micelles
Overview
The horseshoe crab cationic antimicrobial peptide polyphemusin I is highly active in vitro but not protective in mouse models of bacterial and LPS challenge, while a synthetic polyphemusin variant, PV5, was previously shown to be protective in vivo. In this study, we investigated the interaction of these peptides with lipid membranes in an effort to propose a mechanism of interaction. The solution structure of PV5 was determined by proton NMR in the absence and presence of dodecylphosphocholine (DPC) micelles. Like polyphemusin I, PV5 is a beta-hairpin but appeared less amphipathic in solution. Upon association with DPC micelles, PV5 underwent side chain rearrangements which resulted in an increased amphipathic conformation. Using fluorescence spectroscopy, both peptides were found to have limited affinity for neutral vesicles composed of phosphatidylcholine (PC). Incorporation of 25 mol % cholesterol or phosphatidylethanolamine into PC vesicles produced little change in the partitioning of either peptide. Incorporation of 25 mol % phosphatidylglycerol (PG) into PC vesicles, a simple prokaryotic model, resulted in a large increase in the affinity for both peptides, but the partition coefficient for PV5 was almost twice that of polyphemusin I. Differential scanning calorimetry studies supported the partitioning data and demonstrated that neither peptide interacted readily with neutral PC vesicles. Both peptides showed affinity for negatively charged membranes incorporating PG. The affinity of PV5 was much greater as the pretransition peak was absent at low peptide to lipid ratios (1:400) and the reduction in enthalpy of the main transition was greater than that produced by polyphemusin I. Both peptides decreased the lamellar to inverted hexagonal phase transition temperature of PE indicating the induction of negative curvature strain. These results, combined with previous findings that polyphemusin I promotes lipid flip-flop but does not induce significant vesicle leakage, ruled out the torroidal pore and carpet mechanisms of antimicrobial action for these polyphemusins.
About this Structure
2B5K is a Single protein structure of sequence from [1] with as ligand. Full crystallographic information is available from OCA.
Reference
Solution structure and interaction of the antimicrobial polyphemusins with lipid membranes., Powers JP, Tan A, Ramamoorthy A, Hancock RE, Biochemistry. 2005 Nov 29;44(47):15504-13. PMID:16300399
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