1i26
From Proteopedia
(New page: 200px<br /><applet load="1i26" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i26" /> '''SOLUTION STRUCTURE OF PTU-1, A TOXIN FROM TH...) |
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| - | [[Image:1i26.jpg|left|200px]]<br /><applet load="1i26" size=" | + | [[Image:1i26.jpg|left|200px]]<br /><applet load="1i26" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1i26" /> | caption="1i26" /> | ||
'''SOLUTION STRUCTURE OF PTU-1, A TOXIN FROM THE ASSASSIN BUGS PEIRATES TURPIS THAT BLOCKS THE VOLTAGE SENSITIVE CALCIUM CHANNEL N-TYPE'''<br /> | '''SOLUTION STRUCTURE OF PTU-1, A TOXIN FROM THE ASSASSIN BUGS PEIRATES TURPIS THAT BLOCKS THE VOLTAGE SENSITIVE CALCIUM CHANNEL N-TYPE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Ptu1 is a toxin from the assassin bug Peirates turpis which has been | + | Ptu1 is a toxin from the assassin bug Peirates turpis which has been demonstrated to bind reversibly the N-type calcium channels and to have lower affinity than the omega-conotoxin MVIIA. We have determined the solution structure of Ptu1 by use of conventional two-dimensional NMR techniques followed by distance-geometry and molecular dynamics. The calculated structure of Ptu1 belongs to the inhibitory cystin knot structural family (ICK) that consists of a compact disulfide-bonded core from which four loops emerge. Analysis of the 25 converged solutions indicates that the molecular structure of Ptu1 contains a 2-stranded antiparallel beta-sheet (residues 24-27 and 31-34) as the only secondary structure. The loop 2 that has been described to be critical for the binding of the toxin on the channel is similar in Ptu1 and MVIIA. In this loop, the critical residue, Tyr13, in MVIIA is retrieved in Ptu1 as Phe13, but the presence of an acidic residue (Asp16) in Ptu1 could disturb the binding of Ptu1 on the channel and could explain the lower affinity of Ptu1 toward the N-type calcium channel compared to the one of MVIIA. Analysis of the electrostatic charge's repartition gives some insights about the importance of the basic residues, which could interact with acidic residues of the channel and then provide a stabilization of the toxin on the channel. |
==About this Structure== | ==About this Structure== | ||
| - | 1I26 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Peirates_turpis Peirates turpis]. Full crystallographic information is available from [http:// | + | 1I26 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Peirates_turpis Peirates turpis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I26 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: ca channel]] | [[Category: ca channel]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:07:11 2008'' |
Revision as of 11:07, 21 February 2008
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SOLUTION STRUCTURE OF PTU-1, A TOXIN FROM THE ASSASSIN BUGS PEIRATES TURPIS THAT BLOCKS THE VOLTAGE SENSITIVE CALCIUM CHANNEL N-TYPE
Overview
Ptu1 is a toxin from the assassin bug Peirates turpis which has been demonstrated to bind reversibly the N-type calcium channels and to have lower affinity than the omega-conotoxin MVIIA. We have determined the solution structure of Ptu1 by use of conventional two-dimensional NMR techniques followed by distance-geometry and molecular dynamics. The calculated structure of Ptu1 belongs to the inhibitory cystin knot structural family (ICK) that consists of a compact disulfide-bonded core from which four loops emerge. Analysis of the 25 converged solutions indicates that the molecular structure of Ptu1 contains a 2-stranded antiparallel beta-sheet (residues 24-27 and 31-34) as the only secondary structure. The loop 2 that has been described to be critical for the binding of the toxin on the channel is similar in Ptu1 and MVIIA. In this loop, the critical residue, Tyr13, in MVIIA is retrieved in Ptu1 as Phe13, but the presence of an acidic residue (Asp16) in Ptu1 could disturb the binding of Ptu1 on the channel and could explain the lower affinity of Ptu1 toward the N-type calcium channel compared to the one of MVIIA. Analysis of the electrostatic charge's repartition gives some insights about the importance of the basic residues, which could interact with acidic residues of the channel and then provide a stabilization of the toxin on the channel.
About this Structure
1I26 is a Single protein structure of sequence from Peirates turpis. Full crystallographic information is available from OCA.
Reference
Solution structure of Ptu1, a toxin from the assassin bug Peirates turpis that blocks the voltage-sensitive calcium channel N-type., Bernard C, Corzo G, Mosbah A, Nakajima T, Darbon H, Biochemistry. 2001 Oct 30;40(43):12795-800. PMID:11669615
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