1
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Sani MA, Rajput S, Keizer DW, Separovic F. NMR techniques for investigating antimicrobial peptides in model membranes and bacterial cells. Methods 2024; 224:10-20. [PMID: 38295893 DOI: 10.1016/j.ymeth.2024.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 02/05/2024] Open
Abstract
AMPs are short, mainly cationic membrane-active peptides found in all living organism. They perform diverse roles including signaling and acting as a line of defense against bacterial infections. AMPs have been extensively investigated as templates to facilitate the development of novel antimicrobial therapeutics. Understanding the interplay between these membrane-active peptides and the lipid membranes is considered to be a significant step in elucidating the specific mechanism of action of AMPs against prokaryotic and eukaryotic cells to aid the development of new therapeutics. In this review, we have provided a brief overview of various NMR techniques commonly used for studying AMP structure and AMP-membrane interactions in model membranes and whole cells.
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Affiliation(s)
- Marc-Antoine Sani
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia.
| | - Sunnia Rajput
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - David W Keizer
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Frances Separovic
- Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia; School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
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2
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Maillard JY, Pascoe M. Disinfectants and antiseptics: mechanisms of action and resistance. Nat Rev Microbiol 2024; 22:4-17. [PMID: 37648789 DOI: 10.1038/s41579-023-00958-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
Chemical biocides are used for the prevention and control of infection in health care, targeted home hygiene or controlling microbial contamination for various industrial processes including but not limited to food, water and petroleum. However, their use has substantially increased since the implementation of programmes to control outbreaks of methicillin-resistant Staphylococcus aureus, Clostridioides difficile and severe acute respiratory syndrome coronavirus 2. Biocides interact with multiple targets on the bacterial cells. The number of targets affected and the severity of damage will result in an irreversible bactericidal effect or a reversible bacteriostatic one. Most biocides primarily target the cytoplasmic membrane and enzymes, although the specific bactericidal mechanisms vary among different biocide chemistries. Inappropriate usage or low concentrations of a biocide may act as a stressor while not killing bacterial pathogens, potentially leading to antimicrobial resistance. Biocides can also promote the transfer of antimicrobial resistance genes. In this Review, we explore our current understanding of the mechanisms of action of biocides, the bacterial resistance mechanisms encompassing both intrinsic and acquired resistance and the influence of bacterial biofilms on resistance. We also consider the impact of bacteria that survive biocide exposure in environmental and clinical contexts.
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Affiliation(s)
- Jean-Yves Maillard
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Wales, UK.
| | - Michael Pascoe
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Wales, UK
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3
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Has C, Das SL. The Functionality of Membrane-Inserting Proteins and Peptides: Curvature Sensing, Generation, and Pore Formation. J Membr Biol 2023; 256:343-372. [PMID: 37650909 DOI: 10.1007/s00232-023-00289-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/04/2023] [Indexed: 09/01/2023]
Abstract
Proteins and peptides with hydrophobic and amphiphilic segments are responsible for many biological functions. The sensing and generation of membrane curvature are the functions of several protein domains or motifs. While some specific membrane proteins play an essential role in controlling the curvature of distinct intracellular membranes, others participate in various cellular processes such as clathrin-mediated endocytosis, where several proteins sort themselves at the neck of the membrane bud. A few membrane-inserting proteins form nanopores that permeate selective ions and water to cross the membrane. In addition, many natural and synthetic small peptides and protein toxins disrupt the membrane by inducing nonspecific pores in the membrane. The pore formation causes cell death through the uncontrolled exchange between interior and exterior cellular contents. In this article, we discuss the insertion depth and orientation of protein/peptide helices, and their role as a sensor and inducer of membrane curvature as well as a pore former in the membrane. We anticipate that this extensive review will assist biophysicists to gain insight into curvature sensing, generation, and pore formation by membrane insertion.
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Affiliation(s)
- Chandra Has
- Department of Chemical Engineering, GSFC University, Vadodara, 391750, Gujarat, India.
| | - Sovan Lal Das
- Physical and Chemical Biology Laboratory and Department of Mechanical Engineering, Indian Institute of Technology, Palakkad, 678623, Kerala, India
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4
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Podoll JD, Rosen E, Wang W, Gao Y, Zhang J, Wang X. A small-molecule membrane fluidizer re-sensitizes methicillin-resistant Staphylococcus aureus (MRSA) to β-lactam antibiotics. Antimicrob Agents Chemother 2023; 67:e0005123. [PMID: 37681969 PMCID: PMC10583677 DOI: 10.1128/aac.00051-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 06/04/2023] [Indexed: 09/09/2023] Open
Abstract
Novel antibacterial agents and strategies are urgently needed to fight against the ongoing global antibiotic resistance problem. While natural products remain the main source in antibiotic discovery, synthetic antibacterials provide an attractive alternative and may evade the ancient antibiotic resistance. Herein, we report a small molecule that re-sensitizes methicillin-resistant Staphylococcus aureus to β-lactam antibiotics with extremely low potential for resistance development. It belongs to a new class of broad-spectrum antibacterials, trypyricins, which share similar structural characteristics and mechanism of action to the cationic antimicrobial peptides. Mechanistic studies indicated that trypyricins fluidize and disrupt bacterial cytoplasmic membrane. These results suggested that trypyricins represent a promising new class of antibacterials and may be further developed as antibiotic adjuvants to fight against resistant bacteria in the clinic.
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Affiliation(s)
| | - Emma Rosen
- Recreo Pharmaceuticals Inc, Yale Circle, Boulder, Colorado, USA
| | - Wei Wang
- Department of Chemistry, University of Colorado, Boulder, Colorado, USA
| | - Yuefeng Gao
- Department of Chemistry, University of Colorado, Boulder, Colorado, USA
| | - Jing Zhang
- Recreo Pharmaceuticals Inc, Yale Circle, Boulder, Colorado, USA
| | - Xiang Wang
- Department of Chemistry, University of Colorado, Boulder, Colorado, USA
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5
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Separovic F, Hofferek V, Duff AP, McConville MJ, Sani MA. In-cell DNP NMR reveals multiple targeting effect of antimicrobial peptide. J Struct Biol X 2022; 6:100074. [PMID: 36147732 PMCID: PMC9486116 DOI: 10.1016/j.yjsbx.2022.100074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/25/2022] [Accepted: 08/29/2022] [Indexed: 11/28/2022] Open
Abstract
DNP NMR allowed simultaneous monitoring of lipids, proteins and nucleic acids of E. coli cells. The bacterial stress response against an antimicrobial peptide was measured in situ. The antimicrobial peptide maculatin 1.1 significantly compacted nucleic acids in bacteria. Maculatin 1.1 prevented salt bridges forming between membrane lipids.
Dynamic nuclear polarization NMR spectroscopy was used to investigate the effect of the antimicrobial peptide (AMP) maculatin 1.1 on E. coli cells. The enhanced 15N NMR signals from nucleic acids, proteins and lipids identified a number of unanticipated physiological responses to peptide stress, revealing that membrane-active AMPs can have a multi-target impact on E. coli cells. DNP-enhanced 15N-observed 31P-dephased REDOR NMR allowed monitoring how Mac1 induced DNA condensation and prevented intermolecular salt bridges between the main E. coli lipid phosphatidylethanolamine (PE) molecules. The latter was supported by similar results obtained using E. coli PE lipid systems. Overall, the ability to monitor the action of antimicrobial peptides in situ will provide greater insight into their mode of action.
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Affiliation(s)
- Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Vinzenz Hofferek
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Anthony P. Duff
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Kirrawee DC, NSW 2232, Australia
| | - Malcom J. McConville
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia
- Corresponding author.
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Zhu S, Kachooei E, Harmer JR, Brown LJ, Separovic F, Sani MA. TOAC spin-labeled peptides tailored for DNP-NMR studies in lipid membrane environments. Biophys J 2021; 120:4501-4511. [PMID: 34480924 DOI: 10.1016/j.bpj.2021.08.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 07/08/2021] [Accepted: 08/10/2021] [Indexed: 12/15/2022] Open
Abstract
The benefit of combining in-cell solid-state dynamic nuclear polarization (DNP) NMR and cryogenic temperatures is providing sufficient signal/noise and preservation of bacterial integrity via cryoprotection to enable in situ biophysical studies of antimicrobial peptides. The radical source required for DNP was delivered into cells by adding a nitroxide-tagged peptide based on the antimicrobial peptide maculatin 1.1 (Mac1). In this study, the structure, localization, and signal enhancement properties of a single (T-MacW) and double (T-T-MacW) TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid) spin-labeled Mac1 analogs were determined within micelles or lipid vesicles. The solution NMR and circular dichroism results showed that the spin-labeled peptides adopted helical structures in contact with micelles. The peptides behaved as an isolated radical source in the presence of multilamellar vesicles, and the electron paramagnetic resonance (EPR) electron-electron distance for the doubly spin-labeled peptide was ∼1 nm. The strongest paramagnetic relaxation enhancement (PRE) was observed for the lipid NMR signals near the glycerol-carbonyl backbone and was stronger for the doubly spin-labeled peptide. Molecular dynamics simulation of the T-T-MacW radical source in phospholipid bilayers supported the EPR and PRE observations while providing further structural insights. Overall, the T-T-MacW peptide achieved better 13C and 15N signal NMR enhancements and 1H spin-lattice T1 relaxation than T-MacW.
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Affiliation(s)
- Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Ehsan Kachooei
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, University of Queensland, Brisbane, Queensland, Australia
| | - Louise J Brown
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia.
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7
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Zhu S, Li W, O'Brien-Simpson N, Separovic F, Sani MA. C-terminus amidation influences biological activity and membrane interaction of maculatin 1.1. Amino Acids 2021; 53:769-777. [PMID: 33891157 DOI: 10.1007/s00726-021-02983-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/16/2021] [Indexed: 11/24/2022]
Abstract
Cationic antimicrobial peptides have been investigated for their potential use in combating infections by targeting the cell membrane of microbes. Their unique chemical structure has been investigated to understand their mode of action and optimize their dose-response by rationale design. One common feature among cationic AMPs is an amidated C-terminus that provides greater stability against in vivo degradation. This chemical modification also likely modulates the interaction with the cell membrane of bacteria yet few studies have been performed comparing the effect of the capping groups. We used maculatin 1.1 (Mac1) to assess the role of the capping groups in modulating the peptide bacterial efficiency, stability and interactions with lipid membranes. Circular dichroism results showed that C-terminus amidation maintains the structural stability of the peptide (α-helix) in contact with micelles. Dye leakage experiments revealed that amidation of the C-terminus resulted in higher membrane disruptive ability while bacteria and cell viability assays revealed that the amidated form displayed higher antibacterial ability and cytotoxicity compared to the acidic form of Mac1. Furthermore, 31P and 2H solid-state NMR showed that C-terminus amidation played a greater role in disturbance of the phospholipid headgroup but had little effect on the lipid tails. This study paves the way to better understand how membrane-active AMPs act in live bacteria.
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Affiliation(s)
- Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Wenyi Li
- Melbourne Dental School and Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Neil O'Brien-Simpson
- Melbourne Dental School and Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia.
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8
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Zhu S, Weber DK, Separovic F, Sani MA. Expression and purification of the native C-amidated antimicrobial peptide maculatin 1.1. J Pept Sci 2021; 27:e3330. [PMID: 33843136 DOI: 10.1002/psc.3330] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 11/09/2022]
Abstract
Maculatin 1.1 (Mac1) is an antimicrobial peptide (AMP) from an Australian tree frog and exhibits low micromolar activity against Gram-positive bacteria. The antimicrobial properties of Mac1 are linked to its disruption of bacterial lipid membranes, which has been studied extensively by in vitro nuclear magnetic resonance (NMR) spectroscopy and biophysical approaches. Although in vivo NMR has recently proven effective in probing peptide-lipid interplay in live bacterial cells, direct structural characterisation of AMPs has been prohibited by low sensitivity and overwhelming background noise. To overcome this issue, we report a recombinant expression protocol to produce isotopically enriched Mac1. We utilized a double-fusion construct to alleviate toxicity against the Escherichia coli host and generate the native N-free and C-amidated termini Mac1 peptide. The SUMO and intein tags allowed native N-terminus and C-terminal amidation, respectively, to be achieved in a one-pot reaction. The protocol yielded 0.1 mg/L of native, uniformly 15 N-labelled, Mac1, which possessed identical structure and activity to peptide obtained by solid-phase peptide synthesis.
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Affiliation(s)
- Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Daniel K Weber
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
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9
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Podoll J, Olson J, Wang W, Wang X. A Cell-Free Screen for Bacterial Membrane Disruptors Identifies Mefloquine as a Novel Antibiotic Adjuvant. Antibiotics (Basel) 2021; 10:315. [PMID: 33803571 PMCID: PMC8002938 DOI: 10.3390/antibiotics10030315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 03/06/2021] [Accepted: 03/15/2021] [Indexed: 02/07/2023] Open
Abstract
Antibacterial discovery efforts have lagged far behind the need for new antibiotics. An approach that has gained popularity recently is targeting bacterial phospholipid membranes. We leveraged the differences between bacterial and mammalian phospholipid compositions to develop a high-throughput screen that identifies agents that selectively disrupt bacterial membranes while leaving mammalian membranes intact. This approach was used to screen 4480 compounds representing a subset of the Maybridge HitFinderTM V.11 Collection and the Prestwick Chemical Drug Library®. The screen identified 35 "positives" (0.8% hit rate) that preferentially damage bacterial model membranes. Among these, an antimalarial compound, mefloquine, and an aminoglycoside, neomycin, were identified. Further investigation of mefloquine's activity against Staphylococcus aureus showed that it has little antibiotic activity on its own but can alter membrane fluidity, thereby potentiating a β-lactam antibiotic, oxacillin, against both methicillin-susceptible and methicillin-resistant S. aureus. This study indicates that our cell-free screening approach is a promising platform for discovering bacterial membrane disruptors as antibacterials antibiotic adjuvants.
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Affiliation(s)
| | | | | | - Xiang Wang
- Department of Chemistry, University of Colorado, Boulder, CO 80309, USA; (J.P.); (J.O.); (W.W.)
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10
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Bertrand B, Garduño-Juárez R, Munoz-Garay C. Estimation of pore dimensions in lipid membranes induced by peptides and other biomolecules: A review. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183551. [PMID: 33465367 DOI: 10.1016/j.bbamem.2021.183551] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 12/31/2020] [Accepted: 01/04/2021] [Indexed: 02/07/2023]
Abstract
The cytoplasmic membrane is one of the most frequent cell targets of antimicrobial peptides (AMPs) and other biomolecules. Understanding the mechanism of action of AMPs at the molecular level is of utmost importance for designing of new membrane-specific molecules. In particular, the formation of pores, the structure and size of these pores are of great interest and require nanoscale resolution approaches, therefore, biophysical strategies are essential to achieve an understanding of these processes at this scale. In the case of membrane active peptides, pore formation or general membrane disruption is usually the last step before cell death, and so, pore size is generally directly associated to pore structure and stability and loss of cellular homeostasis, implicated in overall peptide activity. Up to date, there has not been a critical review discussing the methods that can be used specifically for estimating the pore dimensions induced by membrane active peptides. In this review we discuss the scope, relevance and popularity of the different biophysical techniques such as liposome leakage experiments, advanced microscopy, neutron or X-ray scattering, electrophysiological techniques and molecular dynamics studies, all of them useful for determining pore structure and dimension.
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Affiliation(s)
- Brandt Bertrand
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México (ICF-UNAM), Avenida Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, Mexico
| | - Ramón Garduño-Juárez
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México (ICF-UNAM), Avenida Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, Mexico
| | - Carlos Munoz-Garay
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México (ICF-UNAM), Avenida Universidad 2001, Chamilpa, 62210 Cuernavaca, Morelos, Mexico.
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11
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Separovic F, Keizer DW, Sani MA. In-cell Solid-State NMR Studies of Antimicrobial Peptides. FRONTIERS IN MEDICAL TECHNOLOGY 2020; 2:610203. [PMID: 35047891 PMCID: PMC8757805 DOI: 10.3389/fmedt.2020.610203] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 11/30/2020] [Indexed: 12/23/2022] Open
Abstract
Antimicrobial peptides (AMPs) have attracted attention as alternatives to classic antibiotics due to their expected limited pressure on bacterial resistance mechanisms. Yet, their modes of action, in particular in vivo, remain to be elucidated. In situ atomistic-scale details of complex biomolecular assemblies is a challenging requirement for deciphering the complex modes of action of AMPs. The large diversity of molecules that modulate complex interactions limits the resolution achievable using imaging methodology. Herein, the latest advances in in-cell solid-state NMR (ssNMR) are discussed, which demonstrate the power of this non-invasive technique to provide atomic details of molecular structure and dynamics. Practical requirements for investigations of intact bacteria are discussed. An overview of recent in situ NMR investigations of the architecture and metabolism of bacteria and the effect of AMPs on various bacterial structures is presented. In-cell ssNMR revealed that the studied AMPs have a disruptive action on the molecular packing of bacterial membranes and DNA. Despite the limited number of studies, in-cell ssNMR is emerging as a powerful technique to monitor in situ the interplay between bacteria and AMPs.
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Affiliation(s)
- Frances Separovic
- School of Chemistry, University of Melbourne, Melbourne, VIC, Australia
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - David W. Keizer
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Marc-Antoine Sani
- School of Chemistry, University of Melbourne, Melbourne, VIC, Australia
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
- *Correspondence: Marc-Antoine Sani
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12
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Le Brun AP, Zhu S, Sani MA, Separovic F. The Location of the Antimicrobial Peptide Maculatin 1.1 in Model Bacterial Membranes. Front Chem 2020; 8:572. [PMID: 32733854 PMCID: PMC7358649 DOI: 10.3389/fchem.2020.00572] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022] Open
Abstract
Maculatin 1.1 (Mac1) is an antimicrobial peptide (AMP) from the skin secretions of Australian tree frogs. In this work, the interaction of Mac1 with anionic phospholipid bilayers was investigated by NMR, circular dichroism (CD) spectroscopy, neutron reflectometry (NR) and molecular dynamics (MD). In buffer, the peptide is unstructured but in the presence of anionic (DPC/LMPG) micelles or (DMPC/DMPG/DHPC) bicelles adopts a helical structure. Addition of the soluble paramagnetic agent gadolinium (Gd-DTPA) into the Mac1-DPC/LMPG micelle solution showed that the N-terminus is more exposed to the hydrophilic Gd-DTPA than the C-terminus in micelles. 2H and 31P solid-state NMR showed that Mac1 had a greater effect on the anionic lipid (DMPG). A deuterium labeled Mac1 used in NR experiments indicated that the AMP spanned across anionic (PC/PG) bilayers, which was compatible with MD simulations. Simulations also showed that Mac1 orientation remained transmembrane in bilayers and wrapped on the surface of the micelles regardless of the lipid or detergent charge. Thus, the peptide orientation appears to be more susceptible to curvature than charged surface. These results support the formation of transmembrane pores by Mac1 in model bacterial membranes.
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Affiliation(s)
- Anton P Le Brun
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, Australia
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13
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Rončević T, Puizina J, Tossi A. Antimicrobial Peptides as Anti-Infective Agents in Pre-Post-Antibiotic Era? Int J Mol Sci 2019; 20:E5713. [PMID: 31739573 PMCID: PMC6887943 DOI: 10.3390/ijms20225713] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 02/06/2023] Open
Abstract
Resistance to antibiotics is one of the main current threats to human health and every year multi-drug resistant bacteria are infecting millions of people worldwide, with many dying as a result. Ever since their discovery, some 40 years ago, the antimicrobial peptides (AMPs) of innate defense have been hailed as a potential alternative to conventional antibiotics due to their relatively low potential to elicit resistance. Despite continued effort by both academia and start-ups, currently there are still no antibiotics based on AMPs in use. In this study, we discuss what we know and what we do not know about these agents, and what we need to know to successfully translate discovery to application. Understanding the complex mechanics of action of these peptides is the main prerequisite for identifying and/or designing or redesigning novel molecules with potent biological activity. However, other aspects also need to be well elucidated, i.e., the (bio)synthetic processes, physiological and pathological contexts of their activity, and a quantitative understanding of how physico-chemical properties affect activity. Research groups worldwide are using biological, biophysical, and algorithmic techniques to develop models aimed at designing molecules with the necessary blend of antimicrobial potency and low toxicity. Shedding light on some open questions may contribute toward improving this process.
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Affiliation(s)
- Tomislav Rončević
- Department of Biology, Faculty of Science, University of Split, 21000 Split, Croatia;
- Laboratory for Aquaculture, Institute of Oceanography and Fisheries, 21000 Split, Croatia
| | - Jasna Puizina
- Department of Biology, Faculty of Science, University of Split, 21000 Split, Croatia;
| | - Alessandro Tossi
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy;
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14
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Wimley WC, Hristova K. The Mechanism of Membrane Permeabilization by Peptides: Still an Enigma. Aust J Chem 2019; 73:96-103. [PMID: 32341596 DOI: 10.1071/ch19449] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Peptide-induced permeabilization of lipid vesicles has been measured for decades and has provided many insights into the sequence-structure-function relationships of membrane-active peptides. However, researchers in the field have noted that many experiments show transient permeabilization, in which a burst of leakage occurs immediately after peptide addition, followed by a slowdown or cessation of leakage before all contents have been released. This widely observed, but rarely studied, phenomenon is not explained by standard equilibrium pore models that are commonly invoked in both experimental and computational studies. Here we discuss observations of transient permeabilization, and we outline a pathway towards understanding this enigmatic phenomenon.
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Affiliation(s)
- William C Wimley
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112
| | - Kalina Hristova
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD 21218
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15
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Insights into conformation and membrane interactions of the acyclic and dicarba-bridged brevinin-1BYa antimicrobial peptides. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2019; 48:701-710. [DOI: 10.1007/s00249-019-01395-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 08/10/2019] [Accepted: 08/13/2019] [Indexed: 02/03/2023]
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16
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Sani MA, Zhu S, Hofferek V, Separovic F. Nitroxide spin-labeled peptides for DNP-NMR in-cell studies. FASEB J 2019; 33:11021-11027. [PMID: 31284743 DOI: 10.1096/fj.201900931r] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Antimicrobial peptides (AMPs) that target lipid membranes show promise as alternatives to conventional antibiotics. However, the molecular mechanisms of membrane perturbation, as most studies are performed in model systems and in-cell structural studies, have yet to be achieved. Solid-state NMR spectroscopy is a valuable technique to investigate peptide-membrane interactions and to determine the structure of peptides, but the short lifespan of bacteria, especially under magic angle spinning conditions, has not permitted in-cell structural studies. Here, we present the first dynamic nuclear polarization (DNP)-NMR in-cell studies of Escherichia coli bacteria incubated with the AMP maculatin 1.1 (Mac1) in combination with novel nitroxide spin-labeled peptides 2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxylic acid (TOAC)-[F3W]-Mac1 (MacW) and TOAC-TOAC-MacW. The in-cell 13C and 15N signal NMR enhancements, and 1H spin-lattice T1 relaxation times showed that TOAC-MacW and TOAC-TOAC-MacW performed better than the more hydrophilic biradical AMUPol used for DNP studies. Furthermore, the pores formed by the AMP increased the signal enhancements and decreased T1 values of specifically 13C- and 15N-labeled Mac1. This approach has a great potential for determining the first in situ structures of AMPs in bacteria.-Sani, M.-A., Zhu, S., Hofferek, V., Separovic, F. Nitroxide spin-labeled peptides for DNP-NMR in-cell studies.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Vinzenz Hofferek
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
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17
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Szymanowski F, Balatti GE, Ambroggio E, Hugo AA, Martini MF, Fidelio GD, Gómez-Zavaglia A, Pickholz M, Pérez PF. Differential activity of lytic α-helical peptides on lactobacilli and lactobacilli-derived liposomes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1069-1077. [PMID: 30878358 DOI: 10.1016/j.bbamem.2019.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 03/06/2019] [Accepted: 03/09/2019] [Indexed: 01/13/2023]
Abstract
Eukaryotic antimicrobial peptides (AMPs) interact with plasma membrane of bacteria, fungi and eukaryotic parasites. Noteworthy, Lactobacillus delbrueckii subsp. lactis (CIDCA 133) and L. delbrueckii subsp. bulgaricus (CIDCA 331) show different susceptibility to human beta-defensins (β-sheet peptides). In the present work we extended the study to α-helical peptides from anuran amphibian (Aurein 1.2, Citropin 1.1 and Maculatin 1.1). We studied the effect on whole bacteria and liposomes formulated with bacterial lipids through growth kinetics, flow cytometry, leakage of liposome content and studies of peptide insertion in lipid monolayers. Growth of strain CIDCA 331 was dramatically inhibited in the presence of all three peptides and minimal inhibitory concentrations were lower than those for strain CIDCA 133. Flow cytometry revealed that AMPs lead to the permeabilization of bacteria. In addition, CIDCA 331-derived liposomes showed high susceptibility, leading to content leakage and structural disruption. Accordingly, peptide insertion in lipid monolayers demonstrated spontaneous interaction of AMPs with CIDCA 331 lipids. In contrast, lipids monolayers from strain CIDCA 133 were less susceptible. Summarizing we demonstrate that the high resistance of the probiotic strain CIDCA 133 to AMPs extends to α helix peptides Aurein, Citropin and Maculatin. This behavior could be ascribed in part to differences in membrane composition. These findings, along with the previously demonstrated resistance to β defensins from human origin, suggest that strain CIDCA 133 is well adapted to host innate immune effectors from both mammals and amphibians thus indicating conserved mechanisms of interaction with key components of the innate immune system.
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Affiliation(s)
- F Szymanowski
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA,-CCT-CONICET La Plata, CICPBA, UNLP), RA-1900, Argentina
| | - G E Balatti
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, IFIBA, Buenos Aires C1428BFA, Argentina.
| | - E Ambroggio
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Departamento de Química Biológica "Dr. Ranwel Caputto", Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X500HUA, Argentina
| | - A A Hugo
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA,-CCT-CONICET La Plata, CICPBA, UNLP), RA-1900, Argentina.
| | - M F Martini
- Departamento de Farmacología, Instituto de la Química y Metabolismo del Fármaco (IQUIMIFA), Facultad de Farmacia y Bioquímica, Cátedra de Química Medicinal, CONICET-Universidad de Buenos Aires, Buenos Aires C1113AAD, Argentina
| | - G D Fidelio
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Departamento de Química Biológica "Dr. Ranwel Caputto", Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X500HUA, Argentina
| | - A Gómez-Zavaglia
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA,-CCT-CONICET La Plata, CICPBA, UNLP), RA-1900, Argentina.
| | - M Pickholz
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, IFIBA, Buenos Aires C1428BFA, Argentina; Departamento de Farmacología, Instituto de la Química y Metabolismo del Fármaco (IQUIMIFA), Facultad de Farmacia y Bioquímica, Cátedra de Química Medicinal, CONICET-Universidad de Buenos Aires, Buenos Aires C1113AAD, Argentina
| | - P F Pérez
- Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA,-CCT-CONICET La Plata, CICPBA, UNLP), RA-1900, Argentina; Cátedra de Microbiología, Facultad de Ciencias Exactas (FCE), UNLP, La Plata, Argentina.
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18
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Abstract
Membrane permeabilizing peptides (MPPs) are as ubiquitous as the lipid bilayer membranes they act upon. Produced by all forms of life, most membrane permeabilizing peptides are used offensively or defensively against the membranes of other organisms. Just as nature has found many uses for them, translational scientists have worked for decades to design or optimize membrane permeabilizing peptides for applications in the laboratory and in the clinic ranging from antibacterial and antiviral therapy and prophylaxis to anticancer therapeutics and drug delivery. Here, we review the field of membrane permeabilizing peptides. We discuss the diversity of their sources and structures, the systems and methods used to measure their activities, and the behaviors that are observed. We discuss the fact that "mechanism" is not a discrete or a static entity for an MPP but rather the result of a heterogeneous and dynamic ensemble of structural states that vary in response to many different experimental conditions. This has led to an almost complete lack of discrete three-dimensional active structures among the thousands of known MPPs and a lack of useful or predictive sequence-structure-function relationship rules. Ultimately, we discuss how it may be more useful to think of membrane permeabilizing peptides mechanisms as broad regions of a mechanistic landscape rather than discrete molecular processes.
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Affiliation(s)
- Shantanu Guha
- Department of Biochemistry and Molecular Biology Tulane University School of Medicine , New Orleans , Louisiana 70112 , United States
| | - Jenisha Ghimire
- Department of Biochemistry and Molecular Biology Tulane University School of Medicine , New Orleans , Louisiana 70112 , United States
| | - Eric Wu
- Department of Biochemistry and Molecular Biology Tulane University School of Medicine , New Orleans , Louisiana 70112 , United States
| | - William C Wimley
- Department of Biochemistry and Molecular Biology Tulane University School of Medicine , New Orleans , Louisiana 70112 , United States
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19
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Mitra M, Asad M, Kumar S, Yadav K, Chaudhary S, Bhavesh NS, Khalid S, Thukral L, Bajaj A. Distinct Intramolecular Hydrogen Bonding Dictates Antimicrobial Action of Membrane-Targeting Amphiphiles. J Phys Chem Lett 2019; 10:754-760. [PMID: 30694679 DOI: 10.1021/acs.jpclett.8b03508] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
As mechanisms underpinning the molecular interactions between membrane-targeting antimicrobials and Gram-negative bacterial membranes at atomistic scale remain elusive, we used cholic acid (CA)-derived amphiphiles with different hydrophobicities as model antimicrobials and assessed the effect of their conformational flexibility on antimicrobial activity. Relative to other hydrophobic counterparts, a compound with a hexyl chain (6) showed the strongest binding with the lipopolysaccharide (LPS) of Gram-negative bacterial membranes and acted as an effective antimicrobial. Biomolecular simulations, validated by complementary approaches, revealed that specific intramolecular hydrogen bonding imparts conformationally rigid character to compound 6. This conformational stability of compound 6 allows minimum but specific interactions of the amphiphile with LPS that are a sum of exothermic processes like electrostatic interactions, membrane insertion, and endothermic contributions from disaggregation of LPS. Therefore, our study reveals that a membrane-targeting mechanism with the help of conformationally selective molecules offers a roadmap for developing future therapeutics against bacterial infections.
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Affiliation(s)
- Madhurima Mitra
- Laboratory of Nanotechnology and Chemical Biology , Regional Centre for Biotechnology , NCR Biotech Science Cluster, third Milestone, Faridabad-Gurgaon Expressway , Faridabad 121001 , Haryana , India
| | - Mohammad Asad
- Laboratory of Nanotechnology and Chemical Biology , Regional Centre for Biotechnology , NCR Biotech Science Cluster, third Milestone, Faridabad-Gurgaon Expressway , Faridabad 121001 , Haryana , India
| | - Sandeep Kumar
- Laboratory of Nanotechnology and Chemical Biology , Regional Centre for Biotechnology , NCR Biotech Science Cluster, third Milestone, Faridabad-Gurgaon Expressway , Faridabad 121001 , Haryana , India
- Manipal Academy of Higher Education , Manipal 576104 , Karnataka , India
| | - Kavita Yadav
- Laboratory of Nanotechnology and Chemical Biology , Regional Centre for Biotechnology , NCR Biotech Science Cluster, third Milestone, Faridabad-Gurgaon Expressway , Faridabad 121001 , Haryana , India
- Manipal Academy of Higher Education , Manipal 576104 , Karnataka , India
| | - Sarika Chaudhary
- CSIR-Institute of Genomics and Integrative Biology , Mathura Road , New Delhi 110025 , India
| | - Neel Sarovar Bhavesh
- International Centre for Genetic Engineering and Biotechnology , Aruna Asaf Ali Marg , New Delhi 110067 , India
| | - Syma Khalid
- School of Chemistry , University of Southampton , Highfield, Southampton SO17 1BJ , United Kingdom
| | - Lipi Thukral
- CSIR-Institute of Genomics and Integrative Biology , Mathura Road , New Delhi 110025 , India
| | - Avinash Bajaj
- Laboratory of Nanotechnology and Chemical Biology , Regional Centre for Biotechnology , NCR Biotech Science Cluster, third Milestone, Faridabad-Gurgaon Expressway , Faridabad 121001 , Haryana , India
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20
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Overall SA, Zhu S, Hanssen E, Separovic F, Sani MA. In Situ Monitoring of Bacteria under Antimicrobial Stress Using 31P Solid-State NMR. Int J Mol Sci 2019; 20:ijms20010181. [PMID: 30621328 PMCID: PMC6337522 DOI: 10.3390/ijms20010181] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/25/2018] [Accepted: 01/01/2019] [Indexed: 11/23/2022] Open
Abstract
In-cell NMR offers great insight into the characterization of the effect of toxins and antimicrobial peptides on intact cells. However, the complexity of intact live cells remains a significant challenge for the analysis of the effect these agents have on different cellular components. Here we show that 31P solid-state NMR can be used to quantitatively characterize the dynamic behaviour of DNA within intact live bacteria. Lipids were also identified and monitored, although 31P dynamic filtering methods indicated a range of dynamic states for phospholipid headgroups. We demonstrate the usefulness of this methodology for monitoring the activity of the antibiotic ampicillin and the antimicrobial peptide (AMP) maculatin 1.1 (Mac1.1) against Gram-negative bacteria. Perturbations in the dynamic behaviour of DNA were observed in treated cells, which indicated additional mechanisms of action for the AMP Mac1.1 not previously reported. This work highlights the value of 31P in-cell solid-state NMR as a tool for assessing the antimicrobial activity of antibiotics and AMPs in bacterial cells.
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Affiliation(s)
- Sarah A Overall
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia.
- Chemistry & Biochemistry Department, UC Santa Cruz, CA 95064, USA.
| | - Shiying Zhu
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia.
| | - Eric Hanssen
- Advanced Microscopy Facility and Department of Biochemistry & Molecular Biology, Bio21 Institute, University of Melbourne, Victoria 3010, Australia.
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia.
| | - Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia.
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21
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Santos RS, Figueiredo C, Azevedo NF, Braeckmans K, De Smedt SC. Nanomaterials and molecular transporters to overcome the bacterial envelope barrier: Towards advanced delivery of antibiotics. Adv Drug Deliv Rev 2018; 136-137:28-48. [PMID: 29248479 DOI: 10.1016/j.addr.2017.12.010] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/10/2017] [Accepted: 12/12/2017] [Indexed: 01/13/2023]
Abstract
With the dramatic consequences of bacterial resistance to antibiotics, nanomaterials and molecular transporters have started to be investigated as alternative antibacterials or anti-infective carrier systems to improve the internalization of bactericidal drugs. However, the capability of nanomaterials/molecular transporters to overcome the bacterial cell envelope is poorly understood. It is critical to consider the sophisticated architecture of bacterial envelopes and reflect how nanomaterials/molecular transporters can interact with these envelopes, being the major aim of this review. The first part of this manuscript overviews the permeability of bacterial envelopes and how it limits the internalization of common antibiotic and novel oligonucleotide drugs. Subsequently we critically discuss the mechanisms that allow nanomaterials/molecular transporters to overcome the bacterial envelopes, focusing on the most promising ones to this end - siderophores, cyclodextrins, metal nanoparticles, antimicrobial/cell-penetrating peptides and fusogenic liposomes. This review may stimulate drug delivery and microbiology scientists in designing effective nanomaterials/molecular transporters against bacterial infections.
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22
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Vasilchenko AS, Vasilchenko AV, Pashkova TM, Smirnova MP, Kolodkin NI, Manukhov IV, Zavilgelsky GB, Sizova EA, Kartashova OL, Simbirtsev AS, Rogozhin EA, Duskaev GK, Sycheva MV. Antimicrobial activity of the indolicidin-derived novel synthetic peptide In-58. J Pept Sci 2018; 23:855-863. [PMID: 29193518 DOI: 10.1002/psc.3049] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 09/28/2017] [Accepted: 10/01/2017] [Indexed: 12/26/2022]
Abstract
Natural peptides with antimicrobial activity are extremely diverse, and peptide synthesis technologies make it possible to significantly improve their properties for specific tasks. Here, we investigate the biological properties of the natural peptide indolicidin and the indolicidin-derived novel synthetic peptide In-58. In-58 was generated by replacing all tryptophan residues on phenylalanine in D-configuration; the α-amino group in the main chain also was modified by unsaturated fatty acid. Compared with indolicidin, In-58 is more bactericidal, more resistant to proteinase K, and less toxic to mammalian cells. Using molecular physics approaches, we characterized the action of In-58 on bacterial cells at the cellular level. Also, we have found that studied peptides damage bacterial membranes. Using the Escherichia coli luminescent biosensor strain MG1655 (pcolD'::lux), we investigated the action of indolicidin and In-58 at the subcellular level. At subinhibitory concentrations, indolicidin and In-58 induced an SOS response. Our data suggest that indolicidin damages the DNA, but bacterial membrane perturbation is its principal mode of action. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
- A S Vasilchenko
- Tyumen State University, ul. Volodarsky, 6, Tyumen, 625003, Russia
| | - A V Vasilchenko
- Tyumen State University, ul. Volodarsky, 6, Tyumen, 625003, Russia
| | - T M Pashkova
- Institute of Cellular and Intracellular Symbiosis, Russian Academy of Sciences, ul. Pionerskaya, Orenburg, 11, Russia
| | - M P Smirnova
- Research Institute of Highly Pure Biopreparations, Pudozhsakya str., St. Petersburg, 197110, Russia
| | - N I Kolodkin
- Research Institute of Highly Pure Biopreparations, Pudozhsakya str., St. Petersburg, 197110, Russia
| | - I V Manukhov
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1, 1st Dorozhny pr., Moscow, 113545, Russia.,Moscow Institute of Physics and Technology (State University), 9 Institutskiy per., Dolgoprudnyi, 141701, Russia
| | - G B Zavilgelsky
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1, 1st Dorozhny pr., Moscow, 113545, Russia
| | - E A Sizova
- All-Russia Research Institute of Beef Cattle Breeding, Russian Academy of Sciences, ul. Pionerskaya, Orenburg, 11, Russia.,Orenburg State University, Pobedy str., Orenburg, 13, Russia
| | - O L Kartashova
- Institute of Cellular and Intracellular Symbiosis, Russian Academy of Sciences, ul. Pionerskaya, Orenburg, 11, Russia
| | - A S Simbirtsev
- Research Institute of Highly Pure Biopreparations, Pudozhsakya str., St. Petersburg, 197110, Russia
| | - E A Rogozhin
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Science, ul. Miklukho-Maklaya, 16, Orenburg, /10, Russia.,Gause Institute of New Antibiotics, ul. Bolshaya Pirogovskaya, Moscow, 11, Russia
| | - G K Duskaev
- All-Russia Research Institute of Beef Cattle Breeding, Russian Academy of Sciences, ul. Pionerskaya, Orenburg, 11, Russia
| | - M V Sycheva
- Institute of Cellular and Intracellular Symbiosis, Russian Academy of Sciences, ul. Pionerskaya, Orenburg, 11, Russia.,Orenburg State Agrarian University, ul. Chelyuskintsev, Orenburg, 18, Russia
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23
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Antimicrobial peptides: biochemical determinants of activity and biophysical techniques of elucidating their functionality. World J Microbiol Biotechnol 2018; 34:62. [PMID: 29651655 DOI: 10.1007/s11274-018-2444-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 04/05/2018] [Indexed: 10/17/2022]
Abstract
Antimicrobial peptides (AMPs) have been established over millennia as powerful components of the innate immune system of many organisms. Due to their broad spectrum of activity and the development of host resistance against them being unlikely, AMPs are strong candidates for controlling drug-resistant pathogenic microbial pathogens. AMPs cause cell death through several independent or cooperative mechanisms involving membrane lysis, non-lytic activity, and/or intracellular mechanisms. Biochemical determinants such as peptide length, primary sequence, charge, secondary structure, hydrophobicity, amphipathicity and host cell membrane composition together influence the biological activities of peptides. A number of biophysical techniques have been used in recent years to study the mechanisms of action of AMPs. This work appraises the molecular parameters that determine the biocidal activity of AMPs and overviews their mechanisms of actions and the diverse biochemical, biophysical and microscopy techniques utilised to elucidate these.
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24
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Zhu S, Sani M, Separovic F. Interaction of cationic antimicrobial peptides from Australian frogs with lipid membranes. Pept Sci (Hoboken) 2018. [DOI: 10.1002/pep2.24061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Shiying Zhu
- School of ChemistryBio21 Institute, University of MelbourneMelbourne VIC3010 Australia
| | - Marc‐Antoine Sani
- School of ChemistryBio21 Institute, University of MelbourneMelbourne VIC3010 Australia
| | - Frances Separovic
- School of ChemistryBio21 Institute, University of MelbourneMelbourne VIC3010 Australia
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25
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Sani MA, Separovic F. Antimicrobial Peptide Structures: From Model Membranes to Live Cells. Chemistry 2017; 24:286-291. [PMID: 29068097 DOI: 10.1002/chem.201704362] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Indexed: 01/12/2023]
Abstract
The rise in antibiotic resistance has led to a renewed interest in antimicrobial peptides (AMPs) that target membranes. The mode of action of AMPs involves the disruption of the lipid bilayer and leads to growth inhibition and death of the bacteria. However, details at the molecular level of how these peptides kill bacteria and the reasons for the observed differences in selectivity remain unclear. Structural information is crucial for defining the molecular mechanism by which these peptides recognize, self-assemble and interact with a particular lipid membrane. Solid-state NMR is a non-invasive technique that allows the study of the structural details of lipid-peptide and peptide-peptide interactions. Following on from studies of antibiotic and lytic peptides, gramicidin A and melittin, respectively, we investigated maculatin 1.1, an AMP from the skin of Australian tree frogs that acts against Gram-positive bacteria. By using perdeuterated phospholipids and specifically labelled peptides, 2 H, 31 P and {31 P}15 N REDOR solid-state NMR experiments have been used to localize, maculatin 1.1 in neutral and anionic model membranes. However, the structure, location and activity depend on the composition of the model membrane and current advances in solid-state NMR spectroscopy now allow structure determination of AMPs in live bacteria.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
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26
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27
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Sani MA, Carne S, Overall SA, Poulhazan A, Separovic F. One pathogen two stones: are Australian tree frog antimicrobial peptides synergistic against human pathogens? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2017; 46:639-646. [PMID: 28478484 DOI: 10.1007/s00249-017-1215-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 02/28/2017] [Accepted: 04/24/2017] [Indexed: 01/10/2023]
Abstract
Antimicrobial peptides (AMPs) may act by targeting the lipid membranes and disrupting the bilayer structure. In this study, three AMPs from the skin of Australian tree frogs, aurein 1.2, maculatin 1.1 and caerin 1.1, were investigated against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and vesicles that mimic their lipid compositions. Furthermore, equimolar mixtures of the peptides were tested to identify any synergistic interactions in antimicrobial activity. Minimum inhibition concentration and minimum bactericidal concentration assays showed significant activity against S. aureus but not against E. coli. Aurein was the least active while maculatin was the most active peptide and some synergistic effects were observed against S. aureus. Circular dichroism experiments showed that, in the presence of phospholipid vesicles, the peptides transitioned from an unstructured to a predominantly helical conformation (>50%), with greater helicity for POPG/TOCL compared to POPE/POPG vesicles. The helical content, however, was less in the presence of live E. coli and S. aureus, 25 and 5%, respectively. Equimolar concentrations of the peptides did not appear to form greater supramolecular structures. Dye release assays showed that aurein required greater concentration than caerin and maculatin to disrupt the lipid bilayers, and mixtures of the peptides did not cooperate to enhance their lytic activity. Overall, aurein, maculatin, and caerin showed moderate synergy in antimicrobial activity against S. aureus without becoming more structured or enhancement of their membrane-disrupting activity in phospholipid vesicles.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia.
| | - Siobhan Carne
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Sarah A Overall
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Alexandre Poulhazan
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia
- Universite Pierre et Marie Curie (Paris VI), 4 Place Jussieu, 75252, Paris Cedex 5, France
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia.
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28
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Alaybeyoglu B, Uluocak BG, Akbulut BS, Ozkirimli E. The effect of a beta-lactamase inhibitor peptide on bacterial membrane structure and integrity: a comparative study. J Pept Sci 2017; 23:374-383. [PMID: 28299853 DOI: 10.1002/psc.2986] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 01/31/2017] [Indexed: 12/31/2022]
Abstract
Co-administration of beta-lactam antibiotics and beta-lactamase inhibitors has been a favored treatment strategy against beta-lactamase-mediated bacterial antibiotic resistance, but the emergence of beta-lactamases resistant to current inhibitors necessitates the discovery of novel non-beta-lactam inhibitors. Peptides derived from the Ala46-Tyr51 region of the beta-lactamase inhibitor protein are considered as potent inhibitors of beta-lactamase; unfortunately, peptide delivery into the cell limits their potential. The properties of cell-penetrating peptides could guide the design of beta-lactamase inhibitory peptides. Here, our goal is to modify the peptide with the sequence RRGHYY that possesses beta-lactamase inhibitory activity under in vitro conditions. Inspired by the work on the cell-penetrating peptide pVEC, our approach involved the addition of the N-terminal hydrophobic residues, LLIIL, from pVEC to the inhibitor peptide to build a chimera. These residues have been reported to be critical in the uptake of pVEC. We tested the potential of RRGHYY and its chimeric derivative as a beta-lactamase inhibitory peptide on Escherichia coli cells and compared the results with the action of the antimicrobial peptide melittin, the beta-lactam antibiotic ampicillin, and the beta-lactamase inhibitor potassium clavulanate to get mechanistic details on their action. Our results show that the addition of LLIIL to the N-terminus of the beta-lactamase inhibitory peptide RRGHYY increases its membrane permeabilizing potential. Interestingly, the addition of this short stretch of hydrophobic residues also modified the inhibitory peptide such that it acquired antimicrobial property. We propose that addition of the hydrophobic LLIIL residues to the peptide N-terminus offers a promising strategy to design novel antimicrobial peptides in the battle against antibiotic resistance. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
- Begum Alaybeyoglu
- Chemical Engineering Department, Bogazici University, Bebek, 34342, Istanbul, Turkey
| | - Bilge Gedik Uluocak
- Advanced Technologies R&D Center, Bogazici University, Bebek, 34342, Istanbul, Turkey
| | | | - Elif Ozkirimli
- Chemical Engineering Department, Bogazici University, Bebek, 34342, Istanbul, Turkey
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29
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Li J, Koh JJ, Liu S, Lakshminarayanan R, Verma CS, Beuerman RW. Membrane Active Antimicrobial Peptides: Translating Mechanistic Insights to Design. Front Neurosci 2017; 11:73. [PMID: 28261050 PMCID: PMC5306396 DOI: 10.3389/fnins.2017.00073] [Citation(s) in RCA: 340] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/31/2017] [Indexed: 01/10/2023] Open
Abstract
Antimicrobial peptides (AMPs) are promising next generation antibiotics that hold great potential for combating bacterial resistance. AMPs can be both bacteriostatic and bactericidal, induce rapid killing and display a lower propensity to develop resistance than do conventional antibiotics. Despite significant progress in the past 30 years, no peptide antibiotic has reached the clinic yet. Poor understanding of the action mechanisms and lack of rational design principles have been the two major obstacles that have slowed progress. Technological developments are now enabling multidisciplinary approaches including molecular dynamics simulations combined with biophysics and microbiology toward providing valuable insights into the interactions of AMPs with membranes at atomic level. This has led to increasingly robust models of the mechanisms of action of AMPs and has begun to contribute meaningfully toward the discovery of new AMPs. This review discusses the detailed action mechanisms that have been put forward, with detailed atomistic insights into how the AMPs interact with bacterial membranes. The review further discusses how this knowledge is exploited toward developing design principles for novel AMPs. Finally, the current status, associated challenges, and future directions for the development of AMP therapeutics are discussed.
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Affiliation(s)
- Jianguo Li
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
- Agency for Science, Technology and Research (ASTAR), Bioinformatics InstituteSingapore, Singapore
- Duke-NUS Graduate Medical School, SRP Neuroscience and BDSingapore, Singapore
| | - Jun-Jie Koh
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
| | - Shouping Liu
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
| | | | - Chandra S. Verma
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
- Agency for Science, Technology and Research (ASTAR), Bioinformatics InstituteSingapore, Singapore
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
- School of Biological Sciences, Nanyang Technological UniversitySingapore, Singapore
| | - Roger W. Beuerman
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
- Duke-NUS Graduate Medical School, SRP Neuroscience and BDSingapore, Singapore
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O'Brien-Simpson NM, Li W, Pantarat N, Hossain MA, Separovic F, Wade JD, Reynolds EC. Fluorescent Ion Efflux Screening Assay for Determining Membrane-Active Peptides. Aust J Chem 2017. [DOI: 10.1071/ch16659] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A major global health threat is the emergence of antibiotic-resistant microbes. Coupled with a lack of development of modified antibiotics, there is a need to develop new antimicrobial molecules and screening assays for them. In this study, we provide proof of concept that a large unilamellar vesicle (LUV) method used to study chloride ion efflux facilitated by ionophores and surfactant-like molecules that disrupt membrane integrity can be adapted to identify membrane-interactive antimicrobial peptides (AMPs) and to screen relative activity of AMPs. Lucigenin was encapsulated in LUVs in the presence of Cl– ion (NaCl), which quenches fluorescence, and then incubated with AMPs in 100 mM NaNO3 buffer. Upon AMP membrane interaction or disruption, the Cl– ion is exchanged with the NO3– ion, and the resultant lucigenin fluorescence is indicative of relative AMP activity. Seven AMPs were synthesized by solid-phase peptide chemistry and incubated with LUVs of different phospholipid compositions. Each AMP resulted in lucigenin fluorescence, which was dose dependent, and the relative fluorescence correlated with the minimum inhibitory concentration and minimum bactericidal concentration values for the corresponding peptide. Furthermore, using mammalian model phospholipid LUVs, lucigenin-induced fluorescence also correlated with the AMP cytotoxicity half-maximal inhibitory concentration values. The proline-rich AMP, Chex1-Arg20, which is non-lytic but interacts with the bacterial membrane resulted in lucigenin fluorescence of bacterial membrane model LUVs but not of mammalian membrane model LUVs. The fluorescent ion efflux assay developed here should have applicability for most AMPs and could be tailored to target particular bacterial species membrane composition, potentially leading to the identification of novel membrane-interactive AMPs. The rapid high-throughput method also allows for screening of relative AMP activity and toxicity before biological testing.
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Lam SJ, O'Brien-Simpson NM, Pantarat N, Sulistio A, Wong EHH, Chen YY, Lenzo JC, Holden JA, Blencowe A, Reynolds EC, Qiao GG. Combating multidrug-resistant Gram-negative bacteria with structurally nanoengineered antimicrobial peptide polymers. Nat Microbiol 2016; 1:16162. [PMID: 27617798 DOI: 10.1038/nmicrobiol.2016.162] [Citation(s) in RCA: 527] [Impact Index Per Article: 65.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 08/02/2016] [Indexed: 12/25/2022]
Abstract
With the recent emergence of reports on resistant Gram-negative 'superbugs', infections caused by multidrug-resistant (MDR) Gram-negative bacteria have been named as one of the most urgent global health threats due to the lack of effective and biocompatible drugs. Here, we show that a class of antimicrobial agents, termed 'structurally nanoengineered antimicrobial peptide polymers' (SNAPPs) exhibit sub-μM activity against all Gram-negative bacteria tested, including ESKAPE and colistin-resistant and MDR (CMDR) pathogens, while demonstrating low toxicity. SNAPPs are highly effective in combating CMDR Acinetobacter baumannii infections in vivo, the first example of a synthetic antimicrobial polymer with CMDR Gram-negative pathogen efficacy. Furthermore, we did not observe any resistance acquisition by A. baumannii (including the CMDR strain) to SNAPPs. Comprehensive analyses using a range of microscopy and (bio)assay techniques revealed that the antimicrobial activity of SNAPPs proceeds via a multimodal mechanism of bacterial cell death by outer membrane destabilization, unregulated ion movement across the cytoplasmic membrane and induction of the apoptotic-like death pathway, possibly accounting for why we did not observe resistance to SNAPPs in CMDR bacteria. Overall, SNAPPs show great promise as low-cost and effective antimicrobial agents and may represent a weapon in combating the growing threat of MDR Gram-negative bacteria.
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Affiliation(s)
- Shu J Lam
- Polymer Science Group, Department of Chemical &Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Neil M O'Brien-Simpson
- Melbourne Dental School and The Bio21 Institute of Molecular Science and Biotechnology, Oral Health CRC, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Namfon Pantarat
- Melbourne Dental School and The Bio21 Institute of Molecular Science and Biotechnology, Oral Health CRC, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Adrian Sulistio
- Polymer Science Group, Department of Chemical &Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Edgar H H Wong
- Polymer Science Group, Department of Chemical &Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Yu-Yen Chen
- Melbourne Dental School and The Bio21 Institute of Molecular Science and Biotechnology, Oral Health CRC, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jason C Lenzo
- Melbourne Dental School and The Bio21 Institute of Molecular Science and Biotechnology, Oral Health CRC, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - James A Holden
- Melbourne Dental School and The Bio21 Institute of Molecular Science and Biotechnology, Oral Health CRC, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anton Blencowe
- Polymer Science Group, Department of Chemical &Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia.,School of Pharmacy and Medical Sciences, Division of Health Sciences, The University of South Australia, Adelaide, South Australia 5000, Australia
| | - Eric C Reynolds
- Melbourne Dental School and The Bio21 Institute of Molecular Science and Biotechnology, Oral Health CRC, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Greg G Qiao
- Polymer Science Group, Department of Chemical &Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
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Li W, O'Brien-Simpson NM, Tailhades J, Pantarat N, Dawson RM, Otvos L, Reynolds EC, Separovic F, Hossain MA, Wade JD. Multimerization of a Proline-Rich Antimicrobial Peptide, Chex-Arg20, Alters Its Mechanism of Interaction with the Escherichia coli Membrane. ACTA ACUST UNITED AC 2016; 22:1250-8. [PMID: 26384569 DOI: 10.1016/j.chembiol.2015.08.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/28/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
A3-APO, a de novo designed branched dimeric proline-rich antimicrobial peptide (PrAMP), is highly effective against a variety of in vivo bacterial infections. We undertook a selective examination of the mechanism for the Gram-negative Escherichia coli bacterial membrane interaction of the monomer (Chex-Arg20), dimer (A3-APO), and tetramer (A3-APO disulfide-linked dimer). All three synthetic peptides were effective at killing E. coli. However, the tetramer was 30-fold more membrane disruptive than the dimer while the monomer showed no membrane activity. Using flow cytometry and high-resolution fluorescent microscopy, it was observed that dimerization and tetramerization of the Chex-Arg20 monomer led to an alteration in the mechanism of action from non-lytic/membrane hyperpolarization to membrane disruption/depolarization. Our findings show that the membrane interaction and permeability of Chex-Arg20 was altered by multimerization.
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Affiliation(s)
- Wenyi Li
- School of Chemistry, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia
| | - Neil M O'Brien-Simpson
- Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC 3010, Australia; Bio21 Institute, University of Melbourne, VIC 3010, Australia
| | - Julien Tailhades
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia
| | - Namfon Pantarat
- Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC 3010, Australia
| | - Raymond M Dawson
- Land Division, Defence Science and Technology Organization, Fishermans Bend, VIC 3207, Australia
| | - Laszlo Otvos
- Department of Biology, Temple University, Philadelphia, PA 19122, USA; Institute of Medical Microbiology, Semmelweis University, Budapest 1089, Hungary
| | - Eric C Reynolds
- Oral Health CRC, Melbourne Dental School, University of Melbourne, VIC 3010, Australia; Bio21 Institute, University of Melbourne, VIC 3010, Australia
| | - Frances Separovic
- School of Chemistry, University of Melbourne, VIC 3010, Australia; Bio21 Institute, University of Melbourne, VIC 3010, Australia
| | - Mohammed Akhter Hossain
- School of Chemistry, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia.
| | - John D Wade
- School of Chemistry, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia.
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Abstract
The structure-function relationship for a family of antimicrobial peptides (AMPs) from the skin of Australian tree frogs is discussed and compared with that of peptide toxins from bee and Australian scorpion venoms. Although these membrane-active peptides induce a similar cellular fate by disrupting the lipid bilayer integrity, their lytic activity is achieved via different modes of action, which are investigated in relation to amino acid sequence, secondary structure, and membrane lipid composition. In order to better understand what structural features govern the interaction between peptides and lipid membranes, cell-penetrating peptides (CPPs), which translocate through the membrane without compromising its integrity, are also discussed. AMPs possess membrane lytic activities that are naturally designed to target the cellular membrane of pathogens or competitors. They are extremely diverse in amino acid composition and often show specificity against a particular strain of microbe. Since our antibiotic arsenal is declining precariously in the face of the rise in multiantibiotic resistance, AMPs increasingly are seen as a promising alternative. In an effort to understand their molecular mechanism, biophysical studies of a myriad of AMPs have been reported, yet no unifying mechanism has emerged, rendering difficult the rational design of drug leads. Similarly, a wide variety of cytotoxic peptides are found in venoms, the best known being melittin, yet again, predicting their activity based on a particular amino acid composition or secondary structure remains elusive. A common feature of these membrane-active peptides is their preference for the lipid environment. Indeed, they are mainly unstructured in solution and, in the presence of lipid membranes, quickly adsorb onto the surface, change their secondary structure, eventually insert into the hydrophobic core of the membrane bilayer, and finally disrupt the bilayer integrity. These steps define the molecular mechanism by which these membrane-active peptides lyse membranes. The last class of membrane-active peptides discussed are the CPPs, which translocate across the lipid bilayer without inducing severe disruption and have potential as drug vehicles. CPPs are typically highly charged and can show antimicrobial activity by targeting an intracellular target rather than via a direct membrane lytic mechanism. A critical aspect in the structure-function relationship of membrane-active peptides is their specific activity relative to the lipid membrane composition of the cell target. Cell membranes have a wide diversity of lipids, and those of eukaryotic and prokaryotic species differ greatly in composition and structure. The activity of AMPs from Australian tree frogs, toxins, and CPPs has been investigated within various lipid systems to assess whether a relationship between peptide and membrane composition could be identified. NMR spectroscopy techniques are being used to gain atomistic details of how these membrane-active peptides interact with model membranes and cells, and in particular, competitive assays demonstrate the difference between affinity and activity for a specific lipid environment. Overall, the interactions between these relatively small sized peptides and various lipid bilayers give insight into how these peptides function at the membrane interface.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21
Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Frances Separovic
- School of Chemistry, Bio21
Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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O’Brien-Simpson NM, Pantarat N, Attard TJ, Walsh KA, Reynolds EC. A Rapid and Quantitative Flow Cytometry Method for the Analysis of Membrane Disruptive Antimicrobial Activity. PLoS One 2016; 11:e0151694. [PMID: 26986223 PMCID: PMC4795541 DOI: 10.1371/journal.pone.0151694] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/02/2016] [Indexed: 11/19/2022] Open
Abstract
We describe a microbial flow cytometry method that quantifies within 3 hours antimicrobial peptide (AMP) activity, termed Minimum Membrane Disruptive Concentration (MDC). Increasing peptide concentration positively correlates with the extent of bacterial membrane disruption and the calculated MDC is equivalent to its MBC. The activity of AMPs representing three different membranolytic modes of action could be determined for a range of Gram positive and negative bacteria, including the ESKAPE pathogens, E. coli and MRSA. By using the MDC50 concentration of the parent AMP, the method provides high-throughput, quantitative screening of AMP analogues. A unique feature of the MDC assay is that it directly measures peptide/bacteria interactions and lysed cell numbers rather than bacteria survival as with MIC and MBC assays. With the threat of multi-drug resistant bacteria, this high-throughput MDC assay has the potential to aid in the development of novel antimicrobials that target bacteria with improved efficacy.
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Affiliation(s)
- Neil M. O’Brien-Simpson
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Namfon Pantarat
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Troy J. Attard
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Katrina A. Walsh
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
| | - Eric C. Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Australia
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Yang XN, Xue DD, Li JY, Liu M, Jia SR, Chu LQ, Wahid F, Zhang YM, Zhong C. Improvement of antimicrobial activity of graphene oxide/bacterial cellulose nanocomposites through the electrostatic modification. Carbohydr Polym 2016; 136:1152-60. [DOI: 10.1016/j.carbpol.2015.10.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 09/21/2015] [Accepted: 10/07/2015] [Indexed: 01/18/2023]
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Sani MA, Henriques ST, Weber D, Separovic F. Bacteria May Cope Differently from Similar Membrane Damage Caused by the Australian Tree Frog Antimicrobial Peptide Maculatin 1.1. J Biol Chem 2015; 290:19853-62. [PMID: 26100634 DOI: 10.1074/jbc.m115.643262] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Indexed: 11/06/2022] Open
Abstract
Maculatin 1.1 (Mac1) is an antimicrobial peptide from the skin of Australian tree frogs and is known to possess selectivity toward Gram-positive bacteria. Although Mac1 has membrane disrupting activity, it is not known how Mac1 selectively targets Gram-positive over Gram-negative bacteria. The interaction of Mac1 with Escherichia coli, Staphylococcus aureus, and human red blood cells (hRBC) and with their mimetic model membranes is here reported. The peptide showed a 16-fold greater growth inhibition activity against S. aureus (4 μM) than against E. coli (64 μM) and an intermediate cytotoxicity against hRBC (30 μM). Surprisingly, Sytox Green uptake monitored by flow cytometry showed that Mac1 compromised both bacterial membranes with similar efficiency at ∼20-fold lower concentration than the reported minimum inhibition concentration against S. aureus. Mac1 also reduced the negative potential of S. aureus and E. coli membrane with similar efficacy. Furthermore, liposomes mimicking the cell membrane of S. aureus (POPG/TOCL) and E. coli (POPE/POPG) were lysed at similar concentrations, whereas hRBC-like vesicles (POPC/SM/Chol) remained mostly intact in the presence of Mac1. Remarkably, when POPG/TOCL and POPE/POPG liposomes were co-incubated, Mac1 did not induce leakage from POPE/POPG liposomes, suggesting a preference toward POPG/TOCL membranes that was supported by surface plasma resonance assays. Interestingly, circular dichroism spectroscopy showed a similar helical conformation in the presence of the anionic liposomes but not the hRBC mimics. Overall, the study showed that Mac1 disrupts bacterial membranes in a similar fashion before cell death events and would preferentially target S. aureus over E. coli or hRBC membranes.
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Affiliation(s)
- Marc-Antoine Sani
- From the School of Chemistry, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia and
| | - Sónia Troeira Henriques
- the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Daniel Weber
- From the School of Chemistry, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia and
| | - Frances Separovic
- From the School of Chemistry, Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia and
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Jamasbi E, Batinovic S, Sharples RA, Sani MA, Robins-Browne RM, Wade JD, Separovic F, Hossain MA. Melittin peptides exhibit different activity on different cells and model membranes. Amino Acids 2014; 46:2759-66. [DOI: 10.1007/s00726-014-1833-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 08/26/2014] [Indexed: 11/30/2022]
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Dye-release assay for investigation of antimicrobial peptide activity in a competitive lipid environment. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:445-50. [PMID: 24906225 DOI: 10.1007/s00249-014-0970-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 05/13/2014] [Accepted: 05/20/2014] [Indexed: 10/25/2022]
Abstract
A dye-release method for investigating the effect of a competitive lipid environment on the activity of two membrane-disrupting antimicrobial peptides (AMP), maculatin 1.1 and aurein 1.2, is presented. The results support the general conclusion that AMP have greater affinity for negatively charged membranes, for example bacterial membranes, than for the neutral membrane surface found in eukaryotic cells, but only within a competitive lipid environment. Indeed, in a single-model membrane environment, both peptides were more potent against neutral vesicles than against charged vesicles. The approach was also used to investigate the effect of pre-incubating the peptides in a neutral lipid environment then introducing charged lipid vesicles. Maculatin was shown to migrate from the neutral lipid bilayers, where pores had already formed, to the charged membrane bilayers. This result was also observed for charged-to-charged bilayers but, interestingly, not for neutral-to-neutral lipid interfaces. Aurein was able to migrate from either lipid environment, indicating weaker binding to lipid membranes, and a different molecular mechanism for lysis of lipid bilayers. Competitive lipid environments could be used to assess other critical conditions that modulate the activity of membrane peptides or proteins.
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Sani MA, O’Brien-Simpson N, Separovic F. Dye Release Experiments with Dextran Loaded Vesicles. Bio Protoc 2014. [DOI: 10.21769/bioprotoc.1190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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O’Brien-Simpson N, Pantarat N, Walsh K, Reynolds E, Sani MA, Separovic F. Bacterial Fluorescent-dextran Diffusion Assay. Bio Protoc 2014. [DOI: 10.21769/bioprotoc.1191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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