'''Spatial Structure and Membrane Permeabilization for Latarcin-1, a Spider Antimicrobial Peptide'''
===Spatial Structure and Membrane Permeabilization for Latarcin-1, a Spider Antimicrobial Peptide===
==Overview==
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Latarcins, linear peptides from the Lachesana tarabaevi spider venom, exhibit a broad-spectrum antimicrobial activity, likely acting on the bacterial cytoplasmic membrane. We study their spatial structures and interaction with model membranes by a combination of experimental and theoretical methods to reveal the structure-activity relationship. In this work, a 26 amino acid peptide, Ltc1, was investigated. Its spatial structure in detergent micelles was determined by (1)H nuclear magnetic resonance (NMR) and refined by Monte Carlo simulations in an implicit water-octanol slab. The Ltc1 molecule was found to form a straight uninterrupted amphiphilic helix comprising 8-23 residues. A dye-leakage fluorescent assay and (31)P NMR spectroscopy established that the peptide does not induce the release of fluorescent marker nor deteriorate the bilayer structure of the membranes. The voltage-clamp technique showed that Ltc1 induces the current fluctuations through planar membranes when the sign of the applied potential coincides with the one across the bacterial inner membrane. This implies that Ltc1 acts on the membranes via a specific mechanism, which is different from the carpet mode demonstrated by another latarcin, Ltc2a, featuring a helix-hinge-helix structure with a hydrophobicity gradient along the peptide chain. In contrast, the hydrophobic surface of the Ltc1 helix is narrow-shaped and extends with no gradient along the axis. We have also disclosed a number of peptides, structurally homologous to Ltc1 and exhibiting similar membrane activity. This indicates that the hydrophobic pattern of the Ltc1 helix and related antimicrobial peptides specifies their activity mechanism. The latter assumes the formation of variable-sized lesions, which depend upon the potential across the membrane.
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{{ABSTRACT_PUBMED_18293934}}
==About this Structure==
==About this Structure==
2PCO is a [[Single protein]] structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PCO OCA].
2PCO is a [[Single protein]] structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PCO OCA].
==Reference==
==Reference==
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[[Category: Continuous helix]]
[[Category: Continuous helix]]
[[Category: Toxin]]
[[Category: Toxin]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 11:52:52 2008''
Revision as of 11:52, 29 July 2008
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Spatial Structure and Membrane Permeabilization for Latarcin-1, a Spider Antimicrobial PeptideSpatial Structure and Membrane Permeabilization for Latarcin-1, a Spider Antimicrobial Peptide
