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Defensins promote fusion and lysis of negatively charged membranes

Defensins promote fusion and lysis of negatively charged membranes Defensins, a family of cationic peptides isolated from mammalian granulocytes and believed to permeabilize membranes, were tested for their ability to cause fusion and lysis of liposomes. Unlike α‐helical peptides whose lytic effects have been extensively studied, the defensins consist primarily of β‐sheet. Defensins fuse and lyse negatively charged liposomes but display reduced activity with neutral liposomes. These and other experiments suggest that fusion and lysis is mediated primarily by electrostatic forces and to a lesser extent, by hydrophobic interactions. Circular dichroism and fluorescence spectroscopy of native defensins indicate that the amphiphilic β‐sheet structure is maintained throughout the fusion process. Taken together, these results support the idea that protein‐mediated membrane fusion depends not only on hydrophobic and electrostatic forces but also on the spatial arrangement of the amino acid residues to form a three‐dimensional amphiphilic structure, which promotes the efficient mixing of the lipids between membranes. A molecular model for membrane fusion by defensins is presented, which takes into account the contributions of electrostatic forces, hydrophobic interactions, and structural amphiphilicity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Protein Science Wiley

Defensins promote fusion and lysis of negatively charged membranes

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References (67)

Publisher
Wiley
Copyright
Copyright © 1993 The Protein Society
ISSN
0961-8368
eISSN
1469-896X
DOI
10.1002/pro.5560020813
pmid
8401215
Publisher site
See Article on Publisher Site

Abstract

Defensins, a family of cationic peptides isolated from mammalian granulocytes and believed to permeabilize membranes, were tested for their ability to cause fusion and lysis of liposomes. Unlike α‐helical peptides whose lytic effects have been extensively studied, the defensins consist primarily of β‐sheet. Defensins fuse and lyse negatively charged liposomes but display reduced activity with neutral liposomes. These and other experiments suggest that fusion and lysis is mediated primarily by electrostatic forces and to a lesser extent, by hydrophobic interactions. Circular dichroism and fluorescence spectroscopy of native defensins indicate that the amphiphilic β‐sheet structure is maintained throughout the fusion process. Taken together, these results support the idea that protein‐mediated membrane fusion depends not only on hydrophobic and electrostatic forces but also on the spatial arrangement of the amino acid residues to form a three‐dimensional amphiphilic structure, which promotes the efficient mixing of the lipids between membranes. A molecular model for membrane fusion by defensins is presented, which takes into account the contributions of electrostatic forces, hydrophobic interactions, and structural amphiphilicity.

Journal

Protein Science – Wiley

Published: Aug 1, 1993

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