1
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Baranova AA, Tyurin AP, Korshun VA, Alferova VA. Sensing of Antibiotic-Bacteria Interactions. Antibiotics (Basel) 2023; 12:1340. [PMID: 37627760 PMCID: PMC10451291 DOI: 10.3390/antibiotics12081340] [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: 07/05/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Sensing of antibiotic-bacteria interactions is an important area of research that has gained significant attention in recent years. Antibiotic resistance is a major public health concern, and it is essential to develop new strategies for detecting and monitoring bacterial responses to antibiotics in order to maintain effective antibiotic development and antibacterial treatment. This review summarizes recent advances in sensing strategies for antibiotic-bacteria interactions, which are divided into two main parts: studies on the mechanism of action for sensitive bacteria and interrogation of the defense mechanisms for resistant ones. In conclusion, this review provides an overview of the present research landscape concerning antibiotic-bacteria interactions, emphasizing the potential for method adaptation and the integration of machine learning techniques in data analysis, which could potentially lead to a transformative impact on mechanistic studies within the field.
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Affiliation(s)
| | | | | | - Vera A. Alferova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, 117997 Moscow, Russia; (A.A.B.); (A.P.T.); (V.A.K.)
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2
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Hilpert K, Rumancev C, Gani J, Collis DWP, Lopez-Perez PM, Garamus VM, Mikut R, Rosenhahn A. Can BioSAXS detect ultrastructural changes of antifungal compounds in Candida albicans?-an exploratory study. Front Pharmacol 2023; 14:1141785. [PMID: 37533629 PMCID: PMC10393279 DOI: 10.3389/fphar.2023.1141785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 07/06/2023] [Indexed: 08/04/2023] Open
Abstract
The opportunistic yeast Candida albicans is the most common cause of candidiasis. With only four classes of antifungal drugs on the market, resistance is becoming a problem in the treatment of fungal infections, especially in immunocompromised patients. The development of novel antifungal drugs with different modes of action is urgent. In 2016, we developed a groundbreaking new medium-throughput method to distinguish the effects of antibacterial agents. Using small-angle X-ray scattering for biological samples (BioSAXS), it is now possible to screen hundreds of new antibacterial compounds and select those with the highest probability for a novel mode of action. However, yeast (eukaryotic) cells are highly structured compared to bacteria. The fundamental question to answer was if the ultrastructural changes induced by the action of an antifungal drug can be detected even when most structures in the cell stay unchanged. In this exploratory work, BioSAXS was used to measure the ultrastructural changes of C. albicans that were directly or indirectly induced by antifungal compounds. For this, the well-characterized antifungal drug Flucytosine was used. BioSAXS measurements were performed on the synchrotron P12 BioSAXS beamline, EMBL (DESY, Hamburg) on treated and untreated yeast C. albicans. BioSAXS curves were analysed using principal component analysis (PCA). The PCA showed that Flucytosine-treated and untreated yeast were separated. Based on that success further measurements were performed on five antifungal peptides {1. Cecropin A-melittin hybrid [CA (1-7) M (2-9)], KWKLFKKIGAVLKVL; 2. Lasioglossin LL-III, VNWKKILGKIIKVVK; 3. Mastoparan M, INLKAIAALAKKLL; 4. Bmkn2, FIGAIARLLSKIFGKR; and 5. optP7, KRRVRWIIW}. The ultrastructural changes of C. albicans indicate that the peptides may have different modes of action compared to Flucytosine as well as to each other, except for the Cecropin A-melittin hybrid [CA (1-7) M (2-9)] and optP7, showing very similar effects on C. albicans. This very first study demonstrates that BioSAXS shows promise to be used for antifungal drug development. However, this first study has limitations and further experiments are necessary to establish this application.
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Affiliation(s)
- Kai Hilpert
- Institute of Infection and Immunology, St. George’s, University of London (SGUL), London, United Kingdom
| | - Christoph Rumancev
- Laboratory Analytical Chemistry—Biointerfaces, Ruhr-University Bochum, Bochum, Germany
| | - Jurnorain Gani
- Institute of Infection and Immunology, St. George’s, University of London (SGUL), London, United Kingdom
| | | | | | | | - Ralf Mikut
- Institute for Automation and Applied Informatics (IAI), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Axel Rosenhahn
- Laboratory Analytical Chemistry—Biointerfaces, Ruhr-University Bochum, Bochum, Germany
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3
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Rumancev C, Rosenhahn A, Hilpert K. BioSAXS-an emerging method to accelerate, enrich and de-risk antimicrobial drug development. Front Pharmacol 2022; 13:947005. [PMID: 36081947 PMCID: PMC9445215 DOI: 10.3389/fphar.2022.947005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial resistance is a worldwide threat to modern health care. Low-profit margin and high risk of cross-resistance resulted in a loss of interest in big pharma, contributing to the increasing threat. Strategies to address the problem are starting to emerge. Novel antimicrobial compounds with novel modes of action are especially valued because they have a lower risk of cross-resistance. Up to now determining the mode of action has been very time and resource consuming and will be performed once drug candidates were already progressed in preclinical development. BioSAXS is emerging as a new method to test up to thousands of compounds to classify them into groups based on ultra-structural changes that correlate to their modes of action. First experiments in E. coli (gram-negative) have demonstrated that using conventional and experimental antimicrobials a classification of compounds according to their mode of action was possible. Results were backed up by transmission electron microscopy. Further work showed that also gram-positive bacteria (Staphylococcus aureus) can be used and the effects of novel antimicrobial peptides on both types of bacteria were studied. Preliminary experiments also show that BioSAXS can be used to classify antifungal drugs, demonstrated on Candida albicans. In summary, BioSAXS can accelerate and enrich the discovery of antimicrobial compounds from screening projects with a novel mode of action and hence de-risk the development of urgently needed antimicrobial drugs.
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Affiliation(s)
- Christoph Rumancev
- Analytical Chemistry, Biointerfaces, Ruhr-University Bochum, Bochum, Germany
| | - Axel Rosenhahn
- Analytical Chemistry, Biointerfaces, Ruhr-University Bochum, Bochum, Germany
| | - Kai Hilpert
- Institute of Infection and Immunology, University of London, London, United Kingdom
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4
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Duarte H, Gummel J, Robles E, Berti D, Fratini E. Ultra-/Small Angle X-ray Scattering (USAXS/SAXS) and Static Light Scattering (SLS) Modeling as a Tool to Determine Structural Changes and Effect on Growth in S. epidermidis. ACS APPLIED BIO MATERIALS 2022; 5:3703-3712. [PMID: 35905477 PMCID: PMC9940853 DOI: 10.1021/acsabm.2c00218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Usually, to characterize bacterial cells' susceptibility to antimicrobials, basic microbiology techniques such as serial dilutions or disk assays are used. In this work, we present an approach focused on combining static light scattering (SLS) and ultra-/small angle X-ray scattering (USAXS/SAXS). This approach was used to support microbiology techniques, with the aim of understanding the structural changes caused to bacteria when they are exposed to different stresses like pH, oxidation, and surfactants. Using USAXS/SAXS and SLS data, we developed a detailed multiscale model for a Gram-positive bacterium, S. epidermidis, and we extracted information regarding changes in the overall size and cell thickness induced by different stresses (i.e., pH and hydrogen peroxide). Increasing the concentration of hydrogen peroxide leads to a progressive reduction in cell wall thickness. Moreover, the concomitant use of pH and hydrogen peroxide provides evidence for a synergy in inhibiting the S. epidermidis growth. These promising results will be used as a starting base to further investigate more complex formulations and improve/refine the data modeling of bacteria in the small angle scattering regime.
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Affiliation(s)
- Hugo Duarte
- Department
of Chemistry “Ugo Schiff” and CSGI, University of Florence, Sesto
Fiorentino, Florence I-50019, Italy,
| | - Jeremie Gummel
- Brussels
Innovation Centre, Temselaan
100, Strombeek-bever B-1853, Belgium
| | - Eric Robles
- Household
Care Analytical, Procter & Gamble Newcastle
Innovation Centre, Newcastle NE12 9TS, United Kingdom
| | - Debora Berti
- Department
of Chemistry “Ugo Schiff” and CSGI, University of Florence, Sesto
Fiorentino, Florence I-50019, Italy
| | - Emiliano Fratini
- Department
of Chemistry “Ugo Schiff” and CSGI, University of Florence, Sesto
Fiorentino, Florence I-50019, Italy,
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5
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Sportelli MC, Kranz C, Mizaikoff B, Cioffi N. Recent advances on the spectroscopic characterization of microbial biofilms: A critical review. Anal Chim Acta 2022; 1195:339433. [DOI: 10.1016/j.aca.2022.339433] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/30/2021] [Accepted: 01/02/2022] [Indexed: 02/07/2023]
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6
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Hilpert K, Gani J, Rumancev C, Simpson N, Lopez-Perez PM, Garamus VM, von Gundlach AR, Markov P, Scocchi M, Mikut R, Rosenhahn A. Rational Designed Hybrid Peptides Show up to a 6-Fold Increase in Antimicrobial Activity and Demonstrate Different Ultrastructural Changes as the Parental Peptides Measured by BioSAXS. Front Pharmacol 2021; 12:769739. [PMID: 34966279 PMCID: PMC8711299 DOI: 10.3389/fphar.2021.769739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/12/2021] [Indexed: 11/27/2022] Open
Abstract
Antimicrobial peptides (AMPs) are a promising class of compounds being developed against multi-drug resistant bacteria. Hybridization has been reported to increase antimicrobial activity. Here, two proline-rich peptides (consP1: VRKPPYLPRPRPRPL-CONH2 and Bac5-v291: RWRRPIRRRPIRPPFWR-CONH2) were combined with two arginine-isoleucine-rich peptides (optP1: KIILRIRWR-CONH2 and optP7: KRRVRWIIW-CONH2). Proline-rich antimicrobial peptides (PrAMPs) are known to inhibit the bacterial ribosome, shown also for Bac5-v291, whereas it is hypothesized a “dirty drug” model for the arginine-isoleucine-rich peptides. That hypothesis was underpinned by transmission electron microscopy and biological small-angle X-ray scattering (BioSAXS). The strength of BioSAXS is the power to detect ultrastructural changes in millions of cells in a short time (seconds) in a high-throughput manner. This information can be used to classify antimicrobial compounds into groups according to the ultrastructural changes they inflict on bacteria and how the bacteria react towards that assault. Based on previous studies, this correlates very well with different modes of action. Due to the novelty of this approach direct identification of the target of the antimicrobial compound is not yet fully established, more research is needed. More research is needed to address this limitation. The hybrid peptides showed a stronger antimicrobial activity compared to the proline-rich peptides, except when compared to Bac5-v291 against E. coli. The increase in activity compared to the arginine-isoleucine-rich peptides was up to 6-fold, however, it was not a general increase but was dependent on the combination of peptides and bacteria. BioSAXS experiments revealed that proline-rich peptides and arginine-isoleucine-rich peptides induce very different ultrastructural changes in E. coli, whereas a hybrid peptide (hyP7B5GK) shows changes, different to both parental peptides and the untreated control. These different ultrastructural changes indicated that the mode of action of the parental peptides might be different from each other as well as from the hybrid peptide hyP7B5GK. All peptides showed very low haemolytic activity, some of them showed a 100-fold or larger therapeutic window, demonstrating the potential for further drug development.
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Affiliation(s)
- Kai Hilpert
- Institute of Infection and Immunology, St. George's, University of London, London, United Kingdom
| | - Jurnorain Gani
- Institute of Infection and Immunology, St. George's, University of London, London, United Kingdom
| | - Christoph Rumancev
- Laboratory Analytical Chemistry - Biointerfaces, Ruhr University Bochum, Bochum, Germany
| | - Nathan Simpson
- Institute of Infection and Immunology, St. George's, University of London, London, United Kingdom
| | | | | | | | - Petar Markov
- European Molecular Biology Laboratory, Hamburg Outstation, Hamburg, Germany
| | - Marco Scocchi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Ralf Mikut
- Institute for Automation and Applied Informatics (IAI), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Axel Rosenhahn
- Laboratory Analytical Chemistry - Biointerfaces, Ruhr University Bochum, Bochum, Germany
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7
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Semeraro EF, Marx L, Mandl J, Frewein MPK, Scott HL, Prévost S, Bergler H, Lohner K, Pabst G. Evolution of the analytical scattering model of live Escherichia coli. J Appl Crystallogr 2021; 54:473-485. [PMID: 33953653 PMCID: PMC8056759 DOI: 10.1107/s1600576721000169] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 01/05/2021] [Indexed: 11/10/2022] Open
Abstract
A previously reported multi-scale model for (ultra-)small-angle X-ray (USAXS/SAXS) and (very) small-angle neutron scattering (VSANS/SANS) of live Escherichia coli was revised on the basis of compositional/metabolomic and ultrastructural constraints. The cellular body is modeled, as previously described, by an ellipsoid with multiple shells. However, scattering originating from flagella was replaced by a term accounting for the oligosaccharide cores of the lipopolysaccharide leaflet of the outer membrane including its cross-term with the cellular body. This was mainly motivated by (U)SAXS experiments showing indistinguishable scattering for bacteria in the presence and absence of flagella or fimbrae. The revised model succeeded in fitting USAXS/SAXS and differently contrasted VSANS/SANS data of E. coli ATCC 25922 over four orders of magnitude in length scale. Specifically, this approach provides detailed insight into structural features of the cellular envelope, including the distance of the inner and outer membranes, as well as the scattering length densities of all bacterial compartments. The model was also successfully applied to E. coli K12, used for the authors' original modeling, as well as for two other E. coli strains. Significant differences were detected between the different strains in terms of bacterial size, intermembrane distance and its positional fluctuations. These findings corroborate the general applicability of the approach outlined here to quantitatively study the effect of bactericidal compounds on ultrastructural features of Gram-negative bacteria without the need to resort to any invasive staining or labeling agents.
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Affiliation(s)
- Enrico F. Semeraro
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Johannes Mandl
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Moritz P. K. Frewein
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
- Institut Laue–Langevin, 38043 Grenoble, France
| | - Haden L. Scott
- University of Tennessee, Center for Environmental Biotechnology, Knoxville, Tennessee, USA
| | | | - Helmut Bergler
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Karl Lohner
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
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8
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Semeraro EF, Marx L, Frewein MPK, Pabst G. Increasing complexity in small-angle X-ray and neutron scattering experiments: from biological membrane mimics to live cells. SOFT MATTER 2021; 17:222-232. [PMID: 32104874 DOI: 10.1039/c9sm02352f] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Small-angle X-ray and neutron scattering are well-established, non-invasive experimental techniques to interrogate global structural properties of biological membrane mimicking systems under physiologically relevant conditions. Recent developments, both in bottom-up sample preparation techniques for increasingly complex model systems, and in data analysis techniques have opened the path toward addressing long standing issues of biological membrane remodelling processes. These efforts also include emerging quantitative scattering studies on live cells, thus enabling a bridging of molecular to cellular length scales. Here, we review recent progress in devising compositional models for joint small-angle X-ray and neutron scattering studies on diverse membrane mimics - with a specific focus on membrane structural coupling to amphiphatic peptides and integral proteins - and live Escherichia coli. In particular, we outline the present state-of-the-art in small-angle scattering methods applied to complex membrane systems, highlighting how increasing system complexity must be followed by an advance in compositional modelling and data-analysis tools.
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Affiliation(s)
- Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria
| | - Moritz P K Frewein
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria and Institut Laue-Langevin, 38000 Grenoble, France
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria
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9
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Malanovic N, Marx L, Blondelle SE, Pabst G, Semeraro EF. Experimental concepts for linking the biological activities of antimicrobial peptides to their molecular modes of action. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183275. [PMID: 32173291 DOI: 10.1016/j.bbamem.2020.183275] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023]
Abstract
The search for novel compounds to combat multi-resistant bacterial infections includes exploring the potency of antimicrobial peptides and derivatives thereof. Complementary to high-throughput screening techniques, biophysical and biochemical studies of the biological activity of these compounds enable deep insight, which can be exploited in designing antimicrobial peptides with improved efficacy. This approach requires the combination of several techniques to study the effect of such peptides on both bacterial cells and simple mimics of their cell envelope, such as lipid-only vesicles. These efforts carry the challenge of bridging results across techniques and sample systems, including the proper choice of membrane mimics. This review describes some important concepts toward the development of potent antimicrobial peptides and how they translate to frequently applied experimental techniques, along with an outline of the biophysics pertaining to the killing mechanism of antimicrobial peptides.
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Affiliation(s)
- Nermina Malanovic
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria.
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria
| | | | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria
| | - Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria
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10
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Raheem N, Straus SK. Mechanisms of Action for Antimicrobial Peptides With Antibacterial and Antibiofilm Functions. Front Microbiol 2019; 10:2866. [PMID: 31921046 PMCID: PMC6927293 DOI: 10.3389/fmicb.2019.02866] [Citation(s) in RCA: 209] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 11/27/2019] [Indexed: 12/14/2022] Open
Abstract
The antibiotic crisis has led to a pressing need for alternatives such as antimicrobial peptides (AMPs). Recent work has shown that these molecules have great potential not only as antimicrobials, but also as antibiofilm agents, immune modulators, anti-cancer agents and anti-inflammatories. A better understanding of the mechanism of action (MOA) of AMPs is an important part of the discovery of more potent and less toxic AMPs. Many models and techniques have been utilized to describe the MOA. This review will examine how biological assays and biophysical methods can be utilized in the context of the specific antibacterial and antibiofilm functions of AMPs.
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Affiliation(s)
- Nigare Raheem
- Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada
| | - Suzana K Straus
- Department of Chemistry, The University of British Columbia, Vancouver, BC, Canada
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11
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von Gundlach A, Ashby MP, Gani J, Lopez-Perez PM, Cookson AR, Ann Huws S, Rumancev C, Garamus VM, Mikut R, Rosenhahn A, Hilpert K. BioSAXS Measurements Reveal That Two Antimicrobial Peptides Induce Similar Molecular Changes in Gram-Negative and Gram-Positive Bacteria. Front Pharmacol 2019; 10:1127. [PMID: 31616307 PMCID: PMC6775230 DOI: 10.3389/fphar.2019.01127] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/30/2019] [Indexed: 01/10/2023] Open
Abstract
Two highly active short broad-spectrum AMPs (14D and 69D) with unknown mode of action have been investigated in regards to their effect against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria methicillin-resistant Staphylococcus aureus (MRSA). Minimal inhibitory concentration (MIC) measurements using a cell density of 108 cfu/ml resulted in values between 16 and 32 µg/ml. Time-kill experiments using 108 cfu/ml revealed complete killing, except for 69D in combination with MRSA, where bacterial load was reduced a million times. Small-angle X-ray scattering of biological samples (BioSAXS) at 108 cfu/ml was applied to investigate the ultrastructural changes in E. coli and MRSA in response to these two broad-spectrum AMPs. In addition, electron microscopy (EM) was performed to visualize the treated and non-treated bacteria. As expected, the scattering curves generated using BioSAXS show the ultrastructure of the Gram-positive and Gram-negative bacteria to be very different (BioSAXS is not susceptible to the outer shape). After treatment with either peptide, the scattering curves of E. coli and MRSA cells are much more alike. Whereas in EM, it is notoriously difficult to observe changes for spherical Gram-positives; the BioSAXS results are superior and reveal strongly similar effects for both peptides induced in Gram-positive as well as Gram-negative bacteria. Given the high-throughput possibility and robust statistics, BioSAXS can support and speed up mode of action research in AMPs and other antimicrobial compounds, making a contribution toward the development of urgently needed drugs against resistant bacteria.
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Affiliation(s)
| | - Martin P Ashby
- Institute of Infection and Immunology, St. George's University of London (SGUL), London, United Kingdom
| | - Jurnorain Gani
- Institute of Infection and Immunology, St. George's University of London (SGUL), London, United Kingdom
| | | | - Alan Roy Cookson
- Institute of Biological, Environmental & Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom
| | - Sharon Ann Huws
- Institute of Global Food Security, School of Biological Sciences, Queens University Belfast, Medical Biology Centre, Belfast, United Kingdom
| | - Christoph Rumancev
- Analytical Chemistry - Biointerfaces, Ruhr-University Bochum, Bochum, Germany
| | - Vasil M Garamus
- Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, Geesthacht, Germany
| | - Ralf Mikut
- Institute for Automation and Applied Informatics (IAI), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Axel Rosenhahn
- Analytical Chemistry - Biointerfaces, Ruhr-University Bochum, Bochum, Germany
| | - Kai Hilpert
- Institute of Infection and Immunology, St. George's University of London (SGUL), London, United Kingdom
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12
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Semeraro EF, Devos JM, Porcar L, Forsyth VT, Narayanan T. In vivo analysis of the Escherichia coli ultrastructure by small-angle scattering. IUCRJ 2017; 4:751-757. [PMID: 29123677 PMCID: PMC5668860 DOI: 10.1107/s2052252517013008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 09/12/2017] [Indexed: 06/07/2023]
Abstract
The flagellated Gram-negative bacterium Escherichia coli is one of the most studied microorganisms. Despite extensive studies as a model prokaryotic cell, the ultrastructure of the cell envelope at the nanometre scale has not been fully elucidated. Here, a detailed structural analysis of the bacterium using a combination of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) and ultra-SAXS (USAXS) methods is presented. A multiscale structural model has been derived by incorporating well established concepts in soft-matter science such as a core-shell colloid for the cell body, a multilayer membrane for the cell wall and self-avoiding polymer chains for the flagella. The structure of the cell envelope was resolved by constraining the model by five different contrasts from SAXS, and SANS at three contrast match points and full contrast. This allowed the determination of the membrane electron-density profile and the inter-membrane distances on a quantitative scale. The combination of USAXS and SAXS covers size scales from micrometres down to nanometres, enabling the structural elucidation of cells from the overall geometry down to organelles, thereby providing a powerful method for a non-invasive investigation of the ultrastructure. This approach may be applied for probing in vivo the effect of detergents, antibiotics and antimicrobial peptides on the bacterial cell wall.
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Affiliation(s)
| | | | | | - V. Trevor Forsyth
- Institut Laue–Langevin, 38042 Grenoble, France
- Life Sciences Department, Keele University, Staffordshire ST5 5BG, England
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13
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Gradzielski M, Allen AJ. Introduction to the special issue on small-angle scattering. J Appl Crystallogr 2016; 49:1858-1860. [PMID: 27980505 PMCID: PMC5139987 DOI: 10.1107/s160057671601904x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
This open-access collection of 11 selected articles covers a small but quite diverse and interesting part of the much wider range of scientific topics presented at the 16th International Conference on Small-Angle Scattering (SAS2015) in Berlin. The topics contained here describe the particular directions in which small-angle scattering is developing at the current moment and which will become increasingly important in the future. The virtual special issue is available at http://journals.iucr.org/special_issues/2016/sas2015/.
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Affiliation(s)
- Michael Gradzielski
- Stranski Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin , Strasse des 17 Juni 124, 10623 Berlin, Germany
| | - Andrew J Allen
- Materials Measurement Science Division, National Institute of Standards and Technology (NIST) , 100 Bureau Drive, Gaithersburg, MD 20899, USA
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