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Abdullah SJ, Mu Y, Bhattacharjya S. Structures, Interactions and Activity of the N-Terminal Truncated Variants of Antimicrobial Peptide Thanatin. Antibiotics (Basel) 2024; 13:74. [PMID: 38247633 PMCID: PMC10812785 DOI: 10.3390/antibiotics13010074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Revised: 01/08/2024] [Accepted: 01/10/2024] [Indexed: 01/23/2024] Open
Abstract
Gram-negative bacteria are intrinsically more resistant to many frontline antibiotics, which is attributed to the permeability barrier of the outer membrane, drug efflux pumps and porins. Consequently, discovery of new small molecules antibiotics to kill drug-resistant Gram-negative bacteria presents a significant challenge. Thanatin, a 21-residue insect-derived antimicrobial peptide, is known for its potent activity against Enterobacter Gram-negative bacteria, including drug-resistant strains. Here, we investigated a 15-residue N-terminal truncated analog PM15 (P1IIYCNRRTGKCQRM15) of thanatin to determine modes of action and antibacterial activity. PM15 and the P1 to Y and A substituted variants PM15Y and PM15A delineated interactions and permeabilization of the LPS-outer membrane. In antibacterial assays, PM15 and the analogs showed growth inhibition of strains of Gram-negative bacteria that is largely dependent on the composition of the culture media. Atomic-resolution structures of PM15 and PM15Y in free solution and in complex with LPS micelle exhibited persistent β-hairpin structures similar to native thanatin. However, in complex with LPS, the structures of peptides are more compact, with extensive packing interactions among residues across the two anti-parallel strands of the β-hairpin. The docked complex of PM15/LPS revealed a parallel orientation of the peptide that may be sustained by potential ionic and van der Waals interactions with the lipid A moiety of LPS. Further, PM15 and PM15Y bind to LptAm, a monomeric functional variant of LptA, the periplasmic component of the seven-protein (A-G) complex involved in LPS transport. Taken together, the structures, target interactions and antibacterial effect of PM15 presented in the current study could be useful in designing thanatin-based peptide analogs.
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Affiliation(s)
| | | | - Surajit Bhattacharjya
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore; (S.J.A.); (Y.M.)
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Bouhrour N, van der Reijden TJK, Voet MM, Schonkeren-Ravensbergen B, Cordfunke RA, Drijfhout JW, Bendali F, Nibbering PH. Novel Antibacterial Agents SAAP-148 and Halicin Combat Gram-Negative Bacteria Colonizing Catheters. Antibiotics (Basel) 2023; 12:1743. [PMID: 38136778 PMCID: PMC10741160 DOI: 10.3390/antibiotics12121743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 12/07/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
The antibiotic management of catheter-related infections (CRIs) often fails owing to the emergence of antimicrobial-resistant strains and/or biofilm/persister apparitions. Thus, we investigated the efficacy of two novel antimicrobial agents, i.e., the synthetic peptide SAAP-148 and the novel antibiotic halicin, against Gram-negative bacteria (GNB) colonizing catheters. The antibacterial, anti-biofilm, and anti-persister activities of both agents were evaluated against Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae strains. The enrolled strains were isolated from catheters and selected based on their resistance to at least three antibiotic classes and biofilm formation potential. Furthermore, the hemolysis and endotoxin neutralization abilities of these agents were explored. The bactericidal activity of both agents was reduced in urine and plasma as compared to buffered saline. In a dose-dependent manner, SAAP-148 and halicin reduced bacterial counts in 24 h preformed biofilms on silicone elastomer discs and eliminated persisters originating from antibiotic-exposed mature 7-day biofilms, with halicin being less effective than SAAP-148. Importantly, SAAP-148 and halicin acted synergistically on E. coli and K. pneumoniae biofilms but not on A. baumannii biofilms. The peptide, but not halicin, decreased the production of IL-12p40 upon exposure to UV-killed bacteria. This preliminary study showed that SAAP-148 and halicin alone/in combination are promising candidates to fight GNB colonizing catheters.
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Affiliation(s)
- Nesrine Bouhrour
- Laboratoire de Microbiologie Appliquée, Faculté des Sciences de la Nature et de la Vie, Université de Bejaia, Bejaia 06000, Algeria
- Department of Infectious Diseases, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (T.J.K.v.d.R.); (M.M.V.); (B.S.-R.); (P.H.N.)
| | - Tanny J. K. van der Reijden
- Department of Infectious Diseases, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (T.J.K.v.d.R.); (M.M.V.); (B.S.-R.); (P.H.N.)
| | - Michella M. Voet
- Department of Infectious Diseases, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (T.J.K.v.d.R.); (M.M.V.); (B.S.-R.); (P.H.N.)
| | - Bep Schonkeren-Ravensbergen
- Department of Infectious Diseases, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (T.J.K.v.d.R.); (M.M.V.); (B.S.-R.); (P.H.N.)
| | - Robert A. Cordfunke
- Department of Immunology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (R.A.C.); (J.W.D.)
| | - Jan Wouter Drijfhout
- Department of Immunology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (R.A.C.); (J.W.D.)
| | - Farida Bendali
- Laboratoire de Microbiologie Appliquée, Faculté des Sciences de la Nature et de la Vie, Université de Bejaia, Bejaia 06000, Algeria
| | - Peter H. Nibbering
- Department of Infectious Diseases, Leiden University Medical Center, 2300 RC Leiden, The Netherlands; (T.J.K.v.d.R.); (M.M.V.); (B.S.-R.); (P.H.N.)
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Bull TJ, Munshi T, Lopez-Perez PM, Tran AC, Cosgrove C, Bartolf A, Menichini M, Rindi L, Parigger L, Malanovic N, Lohner K, Wang CJH, Fatima A, Martin LL, Esin S, Batoni G, Hilpert K. Specific Cationic Antimicrobial Peptides Enhance the Recovery of Low-Load Quiescent Mycobacterium tuberculosis in Routine Diagnostics. Int J Mol Sci 2023; 24:17555. [PMID: 38139385 PMCID: PMC10743970 DOI: 10.3390/ijms242417555] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/07/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023] Open
Abstract
The culture confirmation of Mycobacterium tuberculosis (MTB) remains the gold standard for the diagnosis of Tuberculosis (TB) with culture conversion representing proof of cure. However, over 40% of TB samples fail to isolate MTB even though many patients remain infectious due to the presence of viable non-culturable forms. Previously, we have shown that two short cationic peptides, T14D and TB08L, induce a hormetic response at low concentrations, leading to a stimulation of growth in MTB and the related animal pathogen Mycobacterium bovis (bTB). Here, we examine these peptides showing they can influence the mycobacterial membrane integrity and function through membrane potential reduction. We also show this disruption is associated with an abnormal reduction in transcriptomic signalling from specific mycobacterial membrane sensors that normally monitor the immediate cellular environment and maintain the non-growing phenotype. We observe that exposing MTB or bTB to these peptides at optimal concentrations rapidly represses signalling mechanisms maintaining dormancy phenotypes, which leads to the promotion of aerobic metabolism and conversion into a replicative phenotype. We further show a practical application of these peptides as reagents able to enhance conventional routine culture methods by stimulating mycobacterial growth. We evaluated the ability of a peptide-supplemented sample preparation and culture protocol to isolate the MTB against a gold standard routine method tested in parallel on 255 samples from 155 patients with suspected TB. The peptide enhancement increased the sample positivity rate by 46% and decreased the average time to sample positivity of respiratory/faecal sampling by seven days. The most significant improvements in isolation rates were from sputum smear-negative low-load samples and faeces. The peptide enhancement increased sampling test sensitivity by 19%, recovery in samples from patients with a previously culture-confirmed TB by 20%, and those empirically treated for TB by 21%. We conclude that sample decontamination and culture enhancement with D-enantiomer peptides offer good potential for the much-needed improvement of the culture confirmation of TB.
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Affiliation(s)
- Tim J. Bull
- Institute of Infection and Immunity, St. George’s, University of London, Cranmer Terrace, London SW17 0RE, UK (K.H.)
| | - Tulika Munshi
- Institute of Infection and Immunity, St. George’s, University of London, Cranmer Terrace, London SW17 0RE, UK (K.H.)
| | | | - Andy C. Tran
- Institute of Infection and Immunity, St. George’s, University of London, Cranmer Terrace, London SW17 0RE, UK (K.H.)
| | - Catherine Cosgrove
- St. George’s Hospital NHS Trust, Cranmer Terrace, London SW17 0RE, UK; (C.C.)
| | - Angela Bartolf
- St. George’s Hospital NHS Trust, Cranmer Terrace, London SW17 0RE, UK; (C.C.)
| | - Melissa Menichini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy (L.R.); (S.E.); (G.B.)
| | - Laura Rindi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy (L.R.); (S.E.); (G.B.)
| | - Lena Parigger
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, Humboldstrasse 50/III, 800 Graz, Austria; (L.P.); (K.L.)
| | - Nermina Malanovic
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, Humboldstrasse 50/III, 800 Graz, Austria; (L.P.); (K.L.)
| | - Karl Lohner
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, Humboldstrasse 50/III, 800 Graz, Austria; (L.P.); (K.L.)
| | - Carl J. H. Wang
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia (A.F.); (L.L.M.)
| | - Anam Fatima
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia (A.F.); (L.L.M.)
| | - Lisandra L. Martin
- School of Chemistry, Monash University, Clayton, VIC 3800, Australia (A.F.); (L.L.M.)
| | - Semih Esin
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy (L.R.); (S.E.); (G.B.)
| | - Giovanna Batoni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy (L.R.); (S.E.); (G.B.)
| | - Kai Hilpert
- Institute of Infection and Immunity, St. George’s, University of London, Cranmer Terrace, London SW17 0RE, UK (K.H.)
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Javed A, Balhuizen MD, Pannekoek A, Bikker FJ, Heesterbeek DAC, Haagsman HP, Broere F, Weingarth M, Veldhuizen EJA. Effects of Escherichia coli LPS Structure on Antibacterial and Anti-Endotoxin Activities of Host Defense Peptides. Pharmaceuticals (Basel) 2023; 16:1485. [PMID: 37895956 PMCID: PMC10609994 DOI: 10.3390/ph16101485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/13/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
The binding of Host Defense Peptides (HDPs) to the endotoxin of Gram-negative bacteria has important unsolved aspects. For most HDPs, it is unclear if binding is part of the antibacterial mechanism or whether LPS actually provides a protective layer against HDP killing. In addition, HDP binding to LPS can block the subsequent TLR4-mediated activation of the immune system. This dual activity is important, considering that HDPs are thought of as an alternative to conventional antibiotics, which do not provide this dual activity. In this study, we systematically determine, for the first time, the influence of the O-antigen and Lipid A composition on both the antibacterial and anti-endotoxin activity of four HDPs (CATH-2, PR-39, PMAP-23, and PMAP36). The presence of the O-antigen did not affect the antibacterial activity of any of the tested HDPs. Similarly, modification of the lipid A phosphate (MCR-1 phenotype) also did not affect the activity of the HDPs. Furthermore, assessment of inner and outer membrane damage revealed that CATH-2 and PMAP-36 are profoundly membrane-active and disrupt the inner and outer membrane of Escherichia coli simultaneously, suggesting that crossing the outer membrane is the rate-limiting step in the bactericidal activity of these HDPs but is independent of the presence of an O-antigen. In contrast to killing, larger differences were observed for the anti-endotoxin properties of HDPs. CATH-2 and PMAP-36 were much stronger at suppressing LPS-induced activation of macrophages compared to PR-39 and PMAP-23. In addition, the presence of only one phosphate group in the lipid A moiety reduced the immunomodulating activity of these HDPs. Overall, the data strongly suggest that LPS composition has little effect on bacterial killing but that Lipid A modification can affect the immunomodulatory role of HDPs. This dual activity should be considered when HDPs are considered for application purposes in the treatment of infectious diseases.
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Affiliation(s)
- Ali Javed
- Section of Immunology, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.); (A.P.); (F.B.)
- NMR Spectroscopy, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CS Utrecht, The Netherlands;
| | - Melanie D. Balhuizen
- Section of Molecular Host Defense, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (M.D.B.); (H.P.H.)
| | - Arianne Pannekoek
- Section of Immunology, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.); (A.P.); (F.B.)
| | - Floris J. Bikker
- Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, 1081 LA Amsterdam, The Netherlands;
| | - Dani A. C. Heesterbeek
- Department of Medical Microbiology, University Medical Centre Utrecht, 3584 CX Utrecht, The Netherlands;
| | - Henk P. Haagsman
- Section of Molecular Host Defense, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (M.D.B.); (H.P.H.)
| | - Femke Broere
- Section of Immunology, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.); (A.P.); (F.B.)
| | - Markus Weingarth
- NMR Spectroscopy, Bijvoet Centre for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CS Utrecht, The Netherlands;
| | - Edwin J. A. Veldhuizen
- Section of Immunology, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands; (A.J.); (A.P.); (F.B.)
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