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rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes

Antimicrobial peptides (AMPs) are important potential alternatives to conventional therapies against bacterial infections. rBPI(21) is a 21 kDa peptide based on the N-terminal region of the neutrophil bactericidal/permeability-increasing protein (BPI). This AMP possesses highly selective bactericida...

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Autores principales: Domingues, Marco M., Castanho, Miguel A. R. B., Santos, Nuno C.
Formato: Texto
Lenguaje:English
Publicado: Public Library of Science 2009
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2792722/
https://www.ncbi.nlm.nih.gov/pubmed/20027298
http://dx.doi.org/10.1371/journal.pone.0008385
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author Domingues, Marco M.
Castanho, Miguel A. R. B.
Santos, Nuno C.
author_facet Domingues, Marco M.
Castanho, Miguel A. R. B.
Santos, Nuno C.
author_sort Domingues, Marco M.
collection PubMed
description Antimicrobial peptides (AMPs) are important potential alternatives to conventional therapies against bacterial infections. rBPI(21) is a 21 kDa peptide based on the N-terminal region of the neutrophil bactericidal/permeability-increasing protein (BPI). This AMP possesses highly selective bactericidal effects on Gram-negative bacteria and have affinity for lipopolysaccharide (LPS) which is believed to be at the origin of its neutralizing effect of the LPS segregated into the bloodstream. We aim at understanding the molecular bases of rBPI(21) bactericidal and LPS neutralization actions, using biomembrane model systems. Using dynamic light scattering spectroscopy we demonstrate that rBPI(21) promotes aggregation of negatively charged large unilamellar vesicles (LUV), even in the absence of LPS, and LPS aggregates, while for zwitterionic phosphatidylcholine (POPC) LUV the size remains unchanged. The peptide also promotes the fusion (or hemifusion) of membranes containing phosphatidylglycerol (POPG). The aggregation and fusion of negatively charged LUV are peptide concentration-dependent until massive aggregation is reached, followed by sample flocculation/precipitation. Concomitantly, there is a progressive change in the zeta-potential of the LUV systems and LPS aggregates. LUV systems composed of phosphatidylglycerol (POPG) and lipid mixtures with POPG have higher zeta-potential variations than in the absence of POPG. The interaction of rBPI(21) with lipid vesicles is followed by leakage, with higher effect in POPG-containing membranes. LPS aggregation can be related with a decreased toxicity, possibly by facilitating its clearance by macrophage phagocytosis and/or blocking of LPS specific receptor recognition. Our data indicate that rBPI(21) mechanism of action at the molecular level involves the interaction with the LPS of the outer membrane of Gram-negative bacteria, followed by internalization and leakage induction through the (hemi)fusion of the bacterial outer and inner membranes, both enriched in phosphatidylglycerol.
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spelling pubmed-27927222009-12-22 rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes Domingues, Marco M. Castanho, Miguel A. R. B. Santos, Nuno C. PLoS One Research Article Antimicrobial peptides (AMPs) are important potential alternatives to conventional therapies against bacterial infections. rBPI(21) is a 21 kDa peptide based on the N-terminal region of the neutrophil bactericidal/permeability-increasing protein (BPI). This AMP possesses highly selective bactericidal effects on Gram-negative bacteria and have affinity for lipopolysaccharide (LPS) which is believed to be at the origin of its neutralizing effect of the LPS segregated into the bloodstream. We aim at understanding the molecular bases of rBPI(21) bactericidal and LPS neutralization actions, using biomembrane model systems. Using dynamic light scattering spectroscopy we demonstrate that rBPI(21) promotes aggregation of negatively charged large unilamellar vesicles (LUV), even in the absence of LPS, and LPS aggregates, while for zwitterionic phosphatidylcholine (POPC) LUV the size remains unchanged. The peptide also promotes the fusion (or hemifusion) of membranes containing phosphatidylglycerol (POPG). The aggregation and fusion of negatively charged LUV are peptide concentration-dependent until massive aggregation is reached, followed by sample flocculation/precipitation. Concomitantly, there is a progressive change in the zeta-potential of the LUV systems and LPS aggregates. LUV systems composed of phosphatidylglycerol (POPG) and lipid mixtures with POPG have higher zeta-potential variations than in the absence of POPG. The interaction of rBPI(21) with lipid vesicles is followed by leakage, with higher effect in POPG-containing membranes. LPS aggregation can be related with a decreased toxicity, possibly by facilitating its clearance by macrophage phagocytosis and/or blocking of LPS specific receptor recognition. Our data indicate that rBPI(21) mechanism of action at the molecular level involves the interaction with the LPS of the outer membrane of Gram-negative bacteria, followed by internalization and leakage induction through the (hemi)fusion of the bacterial outer and inner membranes, both enriched in phosphatidylglycerol. Public Library of Science 2009-12-22 /pmc/articles/PMC2792722/ /pubmed/20027298 http://dx.doi.org/10.1371/journal.pone.0008385 Text en Domingues et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Domingues, Marco M.
Castanho, Miguel A. R. B.
Santos, Nuno C.
rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes
title rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes
title_full rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes
title_fullStr rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes
title_full_unstemmed rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes
title_short rBPI(21) Promotes Lipopolysaccharide Aggregation and Exerts Its Antimicrobial Effects by (Hemi)fusion of PG-Containing Membranes
title_sort rbpi(21) promotes lipopolysaccharide aggregation and exerts its antimicrobial effects by (hemi)fusion of pg-containing membranes
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2792722/
https://www.ncbi.nlm.nih.gov/pubmed/20027298
http://dx.doi.org/10.1371/journal.pone.0008385
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