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Potential-dependent permeabilization of plasma membrane by the peptide BTM-P1 derived from the Cry11Bb1 protoxin

Mauricio Arias1, Sergio Orduz, Victor V Lemeshko

  • 1Escuela de Física, Facultad de Ciencias, Universidad Nacional de Colombia, Sede Medellín, Calle 59A, No 63-20, Medellín, Colombia.

Biochimica Et Biophysica Acta
|January 17, 2009
PubMed

Insights

The peptide BTM-P1, derived from Cry11Bb1 protoxin, increases plasma membrane permeability in red blood cells. This pore-forming activity may explain its antimicrobial effects and potential toxicity.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Toxicology

Background:

  • The Cry11Bb1 protoxin is known to have insecticidal properties.
  • Peptides derived from Cry toxins can exhibit antimicrobial activity.
  • Understanding the mechanism of action is crucial for developing new antimicrobial agents.

Purpose of the Study:

  • To investigate the plasma membrane permeabilization activity of the BTM-P1 peptide.
  • To determine the pore size and characteristics formed by BTM-P1.
  • To elucidate the relationship between BTM-P1's permeabilizing activity and its antimicrobial effects.

Main Methods:

  • Dose-response experiments using rat red blood cells to assess BTM-P1 permeabilization.
  • Pore radius determination using osmotic protectants and hemolysis assays.
  • Measurement of light dispersion changes in cell suspensions.
  • Investigation of the effect of plasma membrane potential on BTM-P1 activity using valinomycin.

Main Results:

  • BTM-P1 demonstrated dose-dependent plasma membrane permeabilization of red blood cells (1-4 microg/ml).
  • Pore radii were determined to be approximately 0.5-0.8 nm.
  • Peptide activity was enhanced by induced plasma membrane potential, particularly under hypotonic conditions.

Conclusions:

  • BTM-P1 induces pore formation in cell membranes, contributing to its antimicrobial activity.
  • The activity is potential-dependent, suggesting a mechanism similar to other pore-forming toxins.
  • These findings support a pro-apoptotic role for BTM-P1 in mosquito larval midgut epithelial cells.

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