Staff View: Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa

Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa

The importance of small molecular weight antimicrobial peptides as novel therapeutic agents stems from their ability to act against bacteria, viruses, and fungi. As part of the innate immune system, they are also capable of killing cancerous cells. Herein, we study the interaction between a syntheti...

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Main Authors:	Abou-Zied, O.K., Barbour, A., Al-Sharji, N.A., Philip, K.
Format:	Article
Published:	Royal Society of Chemistry 2015
Subjects:	Q Science (General) QH Natural history
Online Access:	http://eprints.um.edu.my/14498/ http://pubs.rsc.org/en/content/articlelanding/ra/2015/c4ra15246h#!divAbstract
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spelling	my.um.eprints.144982015-12-30T03:40:15Z http://eprints.um.edu.my/14498/ Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa Abou-Zied, O.K. Barbour, A. Al-Sharji, N.A. Philip, K. Q Science (General) QH Natural history The importance of small molecular weight antimicrobial peptides as novel therapeutic agents stems from their ability to act against bacteria, viruses, and fungi. As part of the innate immune system, they are also capable of killing cancerous cells. Herein, we study the interaction between a synthetic cecropin B peptide and a target Pseudomonas aeruginosa (PA) membrane using steady-state and time-resolved fluorescence measurements in order to elucidate the mechanism of membrane rupture. The importance of synthetic cecropin B as a therapeutic peptide stems from its effect against a wide range of bacteria which is indistinguishable from that of naturally occuring cecropins. Fluorescence of cecropin B results from the sole tryptophan residue in the peptide. In order to understand the mechansim of peptide–membrane binding, we modified the original peptide (cecropin B1: KWKVFKKIEKMGRNIRNGIV) by attaching a terminal tryptophan residue (cecropin B2: KWKVFKKIEKMGRNIRNGIVW). Both peptides show a large inhibition effect against a wide range of bacteria, compared to naturally occurring peptides. The fluorescence results show an enhancement in the peak intensity of cecropin B1 upon mixing with the membrane, accompanied by a blue shift. For cecropin B2, a blue shift was observed upon mixing with the PA membrane, but no enhancement in intensity was observed. The results indicate perpendicular penetration of cecropins B1 and B2 from the Lys side where the Trp residue of cecropin B1 is immersed in the PA membrane. Partial quenching of the Trp fluorescence by acrylamide was observed and the values of the Stern–Volmer constants (Ksv) indicate that the Trp molecule penetrates into the membrane, but resides close to the interface region. Two fluorescence lifetimes were measured for the cecropin B1–PA complex which are for two rotamers of Trp. The results point to a degree of flexibility of the local environment around the Trp molecule. A mechanism of membrane disruption is proposed in which the cecropin peptide creates cracks through the negatively charged outer membrane of PA. Royal Society of Chemistry 2015-01-21 Article PeerReviewed Abou-Zied, O.K. and Barbour, A. and Al-Sharji, N.A. and Philip, K. (2015) Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa. RSC Advances, 15. pp. 14214-14220. ISSN 2046-2069 http://pubs.rsc.org/en/content/articlelanding/ra/2015/c4ra15246h#!divAbstract DOI: 10.1039/C4RA15246H
institution	Universiti Malaya
building	UM Library
collection	Institutional Repository
continent	Asia
country	Malaysia
content_provider	Universiti Malaya
content_source	UM Research Repository
url_provider	http://eprints.um.edu.my/
topic	Q Science (General) QH Natural history
spellingShingle	Q Science (General) QH Natural history Abou-Zied, O.K. Barbour, A. Al-Sharji, N.A. Philip, K. Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa
description	The importance of small molecular weight antimicrobial peptides as novel therapeutic agents stems from their ability to act against bacteria, viruses, and fungi. As part of the innate immune system, they are also capable of killing cancerous cells. Herein, we study the interaction between a synthetic cecropin B peptide and a target Pseudomonas aeruginosa (PA) membrane using steady-state and time-resolved fluorescence measurements in order to elucidate the mechanism of membrane rupture. The importance of synthetic cecropin B as a therapeutic peptide stems from its effect against a wide range of bacteria which is indistinguishable from that of naturally occuring cecropins. Fluorescence of cecropin B results from the sole tryptophan residue in the peptide. In order to understand the mechansim of peptide–membrane binding, we modified the original peptide (cecropin B1: KWKVFKKIEKMGRNIRNGIV) by attaching a terminal tryptophan residue (cecropin B2: KWKVFKKIEKMGRNIRNGIVW). Both peptides show a large inhibition effect against a wide range of bacteria, compared to naturally occurring peptides. The fluorescence results show an enhancement in the peak intensity of cecropin B1 upon mixing with the membrane, accompanied by a blue shift. For cecropin B2, a blue shift was observed upon mixing with the PA membrane, but no enhancement in intensity was observed. The results indicate perpendicular penetration of cecropins B1 and B2 from the Lys side where the Trp residue of cecropin B1 is immersed in the PA membrane. Partial quenching of the Trp fluorescence by acrylamide was observed and the values of the Stern–Volmer constants (Ksv) indicate that the Trp molecule penetrates into the membrane, but resides close to the interface region. Two fluorescence lifetimes were measured for the cecropin B1–PA complex which are for two rotamers of Trp. The results point to a degree of flexibility of the local environment around the Trp molecule. A mechanism of membrane disruption is proposed in which the cecropin peptide creates cracks through the negatively charged outer membrane of PA.
format	Article
author	Abou-Zied, O.K. Barbour, A. Al-Sharji, N.A. Philip, K.
author_facet	Abou-Zied, O.K. Barbour, A. Al-Sharji, N.A. Philip, K.
author_sort	Abou-Zied, O.K.
title	Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa
title_short	Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa
title_full	Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa
title_fullStr	Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa
title_full_unstemmed	Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa
title_sort	elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: perpendicular penetration of cecropin b-like peptides into pseudomonas aeruginosa
publisher	Royal Society of Chemistry
publishDate	2015
url	http://eprints.um.edu.my/14498/ http://pubs.rsc.org/en/content/articlelanding/ra/2015/c4ra15246h#!divAbstract
_version_	1643689830630031360
score	13.211869

Elucidating the mechanism of peptide interaction with membranes using the intrinsic fluorescence of tryptophan: Perpendicular penetration of cecropin B-like peptides into Pseudomonas aeruginosa

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