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Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D
The increasing emergence of multi-drug resistant bacteria is a serious threat to public health worldwide. Antimicrobial peptides have attracted attention as potential antibiotics since they are present in all multicellular organisms and act as a first line of defence against invading pathogens. We h...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6943423/ https://www.ncbi.nlm.nih.gov/pubmed/31847173 http://dx.doi.org/10.3390/molecules24244571 |
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author | Lone, Abdullah Thomsen, Thomas T. Nielsen, Josefine Eilsø Thulstrup, Peter W. Klitgaard, Rasmus N. Løbner-Olesen, Anders Lund, Reidar Jenssen, Håvard Hansen, Paul R. |
author_facet | Lone, Abdullah Thomsen, Thomas T. Nielsen, Josefine Eilsø Thulstrup, Peter W. Klitgaard, Rasmus N. Løbner-Olesen, Anders Lund, Reidar Jenssen, Håvard Hansen, Paul R. |
author_sort | Lone, Abdullah |
collection | PubMed |
description | The increasing emergence of multi-drug resistant bacteria is a serious threat to public health worldwide. Antimicrobial peptides have attracted attention as potential antibiotics since they are present in all multicellular organisms and act as a first line of defence against invading pathogens. We have previously identified a small all-d antimicrobial octapeptide amide kk(1-nal)fk(1-nal)k(nle)-NH(2) (D2D) with promising antimicrobial activity. In this work, we have performed a structure-activity relationship study of D2D based on 36 analogues aimed at discovering which elements are important for antimicrobial activity and toxicity. These modifications include an alanine scan, probing variation of hydrophobicity at lys(5) and lys(7), manipulation of amphipathicity, N-and C-termini deletions and lys-arg substitutions. We found that the hydrophobic residues in position 3 (1-nal), 4 (phe), 6 (1-nal) and 8 (nle) are important for antimicrobial activity and to a lesser extent cationic lysine residues in position 1, 2, 5 and 7. Our best analogue 5, showed MICs of 4 µg/mL against A. baumannii, E. coli, P. aeruginosa and S. aureus with a hemolytic activity of 47% against red blood cells. Furthermore, compound 5 kills bacteria in a concentration-dependent manner as shown by time-kill kinetics. Circular dichroism (CD) spectra of D2D and compounds 1–8 showed that they likely fold into α-helical secondary structure. Small angle x-ray scattering (SAXS) experiments showed that a random unstructured polymer-like chains model could explain D2D and compounds 1, 3, 4, 6 and 8. Solution structure of compound 5 can be described with a nanotube structure model, compound 7 can be described with a filament-like structure model, while compound 2 can be described with both models. Lipid interaction probed by small angle X-ray scattering (SAXS) showed that a higher amount of compound 5 (~50–60%) inserts into the bilayer compared to D2D (~30–50%). D2D still remains the lead compound, however compound 5 is an interesting antimicrobial peptide for further investigations due to its nanotube structure and minor improvement to antimicrobial activity compared to D2D. |
format | Online Article Text |
id | pubmed-6943423 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-69434232020-01-10 Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D Lone, Abdullah Thomsen, Thomas T. Nielsen, Josefine Eilsø Thulstrup, Peter W. Klitgaard, Rasmus N. Løbner-Olesen, Anders Lund, Reidar Jenssen, Håvard Hansen, Paul R. Molecules Article The increasing emergence of multi-drug resistant bacteria is a serious threat to public health worldwide. Antimicrobial peptides have attracted attention as potential antibiotics since they are present in all multicellular organisms and act as a first line of defence against invading pathogens. We have previously identified a small all-d antimicrobial octapeptide amide kk(1-nal)fk(1-nal)k(nle)-NH(2) (D2D) with promising antimicrobial activity. In this work, we have performed a structure-activity relationship study of D2D based on 36 analogues aimed at discovering which elements are important for antimicrobial activity and toxicity. These modifications include an alanine scan, probing variation of hydrophobicity at lys(5) and lys(7), manipulation of amphipathicity, N-and C-termini deletions and lys-arg substitutions. We found that the hydrophobic residues in position 3 (1-nal), 4 (phe), 6 (1-nal) and 8 (nle) are important for antimicrobial activity and to a lesser extent cationic lysine residues in position 1, 2, 5 and 7. Our best analogue 5, showed MICs of 4 µg/mL against A. baumannii, E. coli, P. aeruginosa and S. aureus with a hemolytic activity of 47% against red blood cells. Furthermore, compound 5 kills bacteria in a concentration-dependent manner as shown by time-kill kinetics. Circular dichroism (CD) spectra of D2D and compounds 1–8 showed that they likely fold into α-helical secondary structure. Small angle x-ray scattering (SAXS) experiments showed that a random unstructured polymer-like chains model could explain D2D and compounds 1, 3, 4, 6 and 8. Solution structure of compound 5 can be described with a nanotube structure model, compound 7 can be described with a filament-like structure model, while compound 2 can be described with both models. Lipid interaction probed by small angle X-ray scattering (SAXS) showed that a higher amount of compound 5 (~50–60%) inserts into the bilayer compared to D2D (~30–50%). D2D still remains the lead compound, however compound 5 is an interesting antimicrobial peptide for further investigations due to its nanotube structure and minor improvement to antimicrobial activity compared to D2D. MDPI 2019-12-13 /pmc/articles/PMC6943423/ /pubmed/31847173 http://dx.doi.org/10.3390/molecules24244571 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Lone, Abdullah Thomsen, Thomas T. Nielsen, Josefine Eilsø Thulstrup, Peter W. Klitgaard, Rasmus N. Løbner-Olesen, Anders Lund, Reidar Jenssen, Håvard Hansen, Paul R. Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D |
title | Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D |
title_full | Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D |
title_fullStr | Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D |
title_full_unstemmed | Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D |
title_short | Structure-Activity Study of an All-d Antimicrobial Octapeptide D2D |
title_sort | structure-activity study of an all-d antimicrobial octapeptide d2d |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6943423/ https://www.ncbi.nlm.nih.gov/pubmed/31847173 http://dx.doi.org/10.3390/molecules24244571 |
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