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https://hdl.handle.net/2440/4453
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Type: | Journal article |
Title: | The orientation of the antibiotic peptide maculatin 1.1 in DMPG and DMPC lipid bilayers. Support for a pore-forming mechanism |
Author: | Chia, C. Torres, J. Cooper, M. Arkin, I. Bowie, J. |
Citation: | FEBS Letters, 2002; 512(1-3):47-51 |
Publisher: | Elsevier Science BV |
Issue Date: | 2002 |
ISSN: | 0014-5793 1873-3468 |
Statement of Responsibility: | C. S. B. Chia, J. Torres, M. A. Cooper, I. T. Arkin and J. H. Bowie |
Abstract: | Maculatin 1.1 is an antimicrobial peptide isolated from the Australian tree frog Litoria genimaculata that adopts an amphipathic, alpha-helical structure in solution. Its orientation and conformation when incorporated to pre-formed DMPG (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol) and DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) vesicles was determined using polarised Fourier transform infrared-attenuated total reflection infrared and deuterium exchange experiments. For DMPG membranes, our results show insertion of 70% of the maculatin 1.1 molecules, with an angle of insertion of approximately 35 degrees to the membrane normal and with a predominant alpha-helical structure. These results suggest that maculatin 1.1 acts through a pore-forming mechanism to lyse bacterial membranes. A similar degree of insertion in DMPG (65%) and alpha-helical structure was observed for a biologically inactive, less amphipathic maculatin 1.1 analogue, P15A, although the helix tilt was found to be greater (46 degrees) than for maculatin 1.1. Similar experiments performed using DMPC liposomes showed poor insertion, less than 5%, for both maculatin 1.1 and its analogue. In addition, the shape of the amide I band in these samples is consistent with alpha-helix, beta-structure and disordered structures being present in similar proportion. These results clearly show that maculatin 1.1 inserts preferentially in negatively charged membranes (DMPG) which mimic the negatively charged membrane of Gram-positive bacteria. We attribute the high percentage of insertion of the biologically inactive analogue in DMPG to the fact that its concentration on the membrane surface in our experiments is likely to be much higher than that found in physiological conditions. |
Keywords: | Lipid Bilayers Dimyristoylphosphatidylcholine Phosphatidylglycerols Antimicrobial Cationic Peptides Amphibian Proteins Ion Channels Anti-Bacterial Agents Spectroscopy, Fourier Transform Infrared Amino Acid Sequence Protein Structure, Secondary Models, Molecular Molecular Sequence Data |
Description: | Copyright © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. |
DOI: | 10.1016/S0014-5793(01)03313-0 |
Description (link): | http://www.elsevier.com/wps/find/journaldescription.cws_home/506085/description#description |
Published version: | http://dx.doi.org/10.1016/s0014-5793(01)03313-0 |
Appears in Collections: | Aurora harvest 6 Chemistry publications |
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