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The effect of binding of spider-derived antimicrobial peptides, oxyopinins, on lipid membranes

Kaoru Nomura1, Gerardo Corzo

  • 1Suntory Institute for Bioorganic Research, 1-1-1 Wakayamadai, Shimamoto-Cho, Mishima-Gun, Osaka 618-8503, Japan. nomura@sunbor.or.jp <nomura@sunbor.or.jp>

Biochimica Et Biophysica Acta
|June 17, 2006
PubMed

Insights

Oxyopinins, antimicrobial peptides from wolf spider venom, disrupt bacterial membranes by altering lipid bilayer structure. Oxki1 and Oxki2 peptides show distinct effects on membrane curvature and micellization.

Area of Science:

  • Biochemistry
  • Biophysics
  • Molecular Biology

Background:

  • Oxyopinins (Oxki1 and Oxki2) are antimicrobial peptides derived from the wolf spider Oxyopes kitabensis venom.
  • Antimicrobial peptides are crucial in innate immunity and represent a promising source for novel therapeutics.

Purpose of the Study:

  • To elucidate the interaction mechanism of oxyopinins (Oxki1 and Oxki2) with lipid bilayers.
  • To investigate the structural and functional consequences of oxyopinins binding to membranes.

Main Methods:

  • High-sensitivity titration calorimetry was employed to quantify the thermodynamic parameters of oxyopinins binding to lipid vesicles.
  • (31)P solid-state NMR spectroscopy was utilized to probe the structural changes and lipid dynamics induced by oxyopinins in various membrane models.

Main Results:

  • Oxyopinins exhibited exothermic binding to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) small unilamellar vesicles, with significant binding enthalpies.
  • Both peptides induced positive curvature in 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) membranes, with Oxki2 showing a stronger effect.
  • Oxki2 induced micellization of phosphaditylcholine (PC) membranes at low concentrations, a process inhibited by unsaturated PCs or acidic phospholipids.
  • Oxki1 demonstrated greater disruption of bacterial membranes (E. coli lipids) compared to Oxki2.

Conclusions:

  • Oxyopinins interact with lipid bilayers through exothermic binding and induce significant membrane perturbations.
  • The distinct effects of Oxki1 and Oxki2 on membrane curvature and stability correlate with their known antimicrobial activities.
  • These findings provide insights into the molecular mechanisms underlying oxyopinin-mediated membrane disruption and their potential as antimicrobial agents.

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