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Multifunctional, Micropipette-based Method for Incorporation And Stimulation of Bacterial Mechanosensitive Ion Channels in Droplet Interface Bilayers
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Multifunctional, Micropipette-based Method for Incorporation And Stimulation of Bacterial Mechanosensitive Ion Channels in Droplet Interface Bilayers

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[Polymyxin B and Ca(2+) induce conductance fluctuations in the dipalmitoyl phosphatidic acid bilayer lipid membrane]

E A Korepanova1, E V Shevchenko, E T Kozhomkulov

  • 1Russian State Medical University, Moscow, Russia.

Biofizika
|April 25, 2000
PubMed

Insights

Polymyxin B and Ca2+ create ion channels in lipid membranes by inducing lipid phase separation. This structural change, detected by calorimetry, is crucial for channel formation in dipalmitoylphosphatidic acid membranes.

Area of Science:

  • Biophysics
  • Membrane Biophysics
  • Lipid Bilayer Studies

Background:

  • Lipid bilayer membranes are fundamental to cell structure and function.
  • Understanding ion channel formation is critical for pharmacology and cell physiology.
  • Dipalmitoylphosphatidic acid (DPPA) is a common phospholipid model system.

Purpose of the Study:

  • To investigate the mechanism of ion channel formation in DPPA lipid membranes induced by Polymyxin B and Ca2+.
  • To correlate ion channel appearance with lipid structural changes.
  • To explore the role of phase transitions in channel formation.

Main Methods:

  • Electrophysiology to detect current fluctuations (ion channels).
  • Differential scanning calorimetry (DSC) to monitor lipid phase transitions.
  • Utilizing liquid crystalline bilayer lipid membranes composed of dipalmitoylphosphatidic acid.

Main Results:

  • Polymyxin B induced ion channel activity in DPPA membranes at micromolar concentrations.
  • Ion channel formation correlated with lipid phase separation, detected by DSC.
  • Ca2+ also induced ion channels in DPPA membranes, accompanied by phospholipid phase transitions.
  • Capacitive currents indicated bilayer-to-non-bilayer (hexagonal phase II) transitions preceding Ca2+-induced channel formation.

Conclusions:

  • Polymyxin B and Ca2+ act as inducers of ion channel formation in DPPA lipid membranes.
  • Lipid phase separation and structural transitions are key events in the mechanism of ion channel formation.
  • These findings provide insights into the interaction of peptides and ions with lipid membranes.

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