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Polańska O, Szulc N, Stottko R, Olek M, Nadwodna J, Gąsior-Głogowska M, Szefczyk M. Challenges in Peptide Solubilization - Amyloids Case Study. CHEM REC 2024:e202400053. [PMID: 39023378 DOI: 10.1002/tcr.202400053] [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: 03/18/2024] [Revised: 05/23/2024] [Indexed: 07/20/2024]
Abstract
Peptide science has been a rapidly growing research field because of the enormous potential application of these biocompatible and bioactive molecules. However, many factors limit the widespread use of peptides in medicine, and low solubility is among the most common problems that hamper drug development in the early stages of research. Solubility is a crucial, albeit poorly understood, feature that determines peptide behavior. Several different solubility predictors have been proposed, and many strategies and protocols have been reported to dissolve peptides, but none of them is a one-size-fits-all method for solubilization of even the same peptide. In this review, we look for the reasons behind the difficulties in dissolving peptides, analyze the factors influencing peptide aggregation, conduct a critical analysis of solubilization strategies and protocols available in the literature, and give some tips on how to deal with the so-called difficult sequences. We focus on amyloids, which are particularly difficult to dissolve and handle such as amyloid beta (Aβ), insulin, and phenol-soluble modulins (PSMs).
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Affiliation(s)
- Oliwia Polańska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wroclaw, Poland
| | - Natalia Szulc
- Department of Physics and Biophysics, Wroclaw University of Environmental and Life Sciences, Norwida 25, 50-375, Wrocław, Poland
| | - Rafał Stottko
- Faculty of Chemistry, Wrocław University of Science and Technology, Gdanska 7/9, 50-344, Wrocław, Poland
| | - Mateusz Olek
- Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, Traugutta 2, 41-800 Zabrze, Poland
| | - Julita Nadwodna
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wroclaw, Poland
| | - Marlena Gąsior-Głogowska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wroclaw, Poland
| | - Monika Szefczyk
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wroclaw, Poland
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2
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Bonnecaze L, Jumel K, Vial A, Khemtemourian L, Feuillie C, Molinari M, Lecomte S, Mathelié-Guinlet M. N-Formylation modifies membrane damage associated with PSMα3 interfacial fibrillation. NANOSCALE HORIZONS 2024; 9:1175-1189. [PMID: 38689531 DOI: 10.1039/d4nh00088a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The virulence of Staphylococcus aureus, a multi-drug resistant pathogen, notably depends on the expression of the phenol soluble modulins α3 (PSMα3) peptides, able to self-assemble into amyloid-like cross-α fibrils. Despite remarkable advances evidencing the crucial, yet insufficient, role of fibrils in PSMα3 cytotoxic activities towards host cells, the relationship between its molecular structures, assembly propensities, and modes of action remains an open intriguing problem. In this study, combining atomic force microscopy (AFM) imaging and infrared spectroscopy, we first demonstrated in vitro that the charge provided by the N-terminal capping of PSMα3 alters its interactions with model membranes of controlled lipid composition without compromising its fibrillation kinetics or morphology. N-formylation eventually dictates PSMα3-membrane binding via electrostatic interactions with the lipid head groups. Furthermore, PSMα3 insertion within the lipid bilayer is favoured by hydrophobic interactions with the lipid acyl chains only in the fluid phase of membranes and not in the gel-like ordered domains. Strikingly, our real-time AFM imaging emphasizes how intermediate protofibrillar entities, formed along PSMα3 self-assembly and promoted at the membrane interface, likely disrupt membrane integrity via peptide accumulation and subsequent membrane thinning in a peptide concentration and lipid-dependent manner. Overall, our multiscale and multimodal approach sheds new light on the key roles of N-formylation and intermediate self-assembling entities, rather than mature fibrils, in dictating deleterious interactions of PSMα3 with membrane lipids, likely underscoring its ultimate cellular toxicity in vivo, and in turn S. aureus pathogenesis.
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Affiliation(s)
- Laura Bonnecaze
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.
| | - Katlyn Jumel
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.
| | - Anthony Vial
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.
| | | | - Cécile Feuillie
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.
| | - Michael Molinari
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.
| | - Sophie Lecomte
- Univ. Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.
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3
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Lichota A, Gwozdzinski K, Kowalczyk E, Kowalczyk M, Sienkiewicz M. Contribution of staphylococcal virulence factors in the pathogenesis of thrombosis. Microbiol Res 2024; 283:127703. [PMID: 38537329 DOI: 10.1016/j.micres.2024.127703] [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: 08/23/2023] [Revised: 03/20/2024] [Accepted: 03/20/2024] [Indexed: 04/17/2024]
Abstract
Staphylococci are responsible for many infections in humans, starting with skin and soft tissue infections and finishing with invasive diseases such as endocarditis, sepsis and pneumonia, which lead to high mortality. Patients with sepsis often demonstrate activated clotting pathways, decreased levels of anticoagulants, decreased fibrinolysis, activated endothelial surfaces and activated platelets. This results in disseminated intravascular coagulation and formation of a microthrombus, which can lead to a multiorgan failure. This review describes various staphylococcal virulence factors that contribute to vascular thrombosis, including deep vein thrombosis in infected patients. The article presents mechanisms of action of different factors released by bacteria in various host defense lines, which in turn can lead to formation of blood clots in the vessels.
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Affiliation(s)
- Anna Lichota
- Department of Pharmaceutical Microbiology and Microbiological Diagnostics, Medical University of Lodz, Lodz, Poland.
| | | | - Edward Kowalczyk
- Department of Pharmacology and Toxicology, Medical University of Lodz, Lodz, Poland
| | | | - Monika Sienkiewicz
- Department of Pharmaceutical Microbiology and Microbiological Diagnostics, Medical University of Lodz, Lodz, Poland
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4
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Kalitnik A, Szefczyk M, Wojciechowska AW, Wojciechowski JW, Gąsior-Głogowska M, Olesiak-Bańska J, Kotulska M. Cytotoxic Staphylococcus aureus PSMα3 inhibits the aggregation of human insulin in vitro. Phys Chem Chem Phys 2024; 26:15587-15599. [PMID: 38757742 DOI: 10.1039/d4cp00669k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
Phenol-soluble modulins (PSMs) are extracellular short amphipathic peptides secreted by the bacteria Staphylococcus aureus (S. aureus). They play an essential role in the bacterial lifecycle, biofilm formation, and stabilisation. From the PSM family, PSMα3 has been of special interest recently due to its cytotoxicity and highly stable α-helical conformation, which also remains in its amyloid fibrils. In particular, PSMα3 fibrils were shown to be composed of self-associating "sheets" of α-helices oriented perpendicular to the fibril axis, mimicking the architecture of canonical cross-β fibrils. Therefore, they were called cross-α-fibrils. PSMα3 was synthesised and verified for identity with wild-type sequences (S. aureus). Then, using several experimental techniques, we evaluated its propensity for in vitro aggregation. According to our findings, synthetic PSMα3 (which lacks the N-terminal formyl groups found in bacteria) does not form amyloid fibrils and maintains α-helical conformation in a soluble monomeric form for several days of incubation. We also evaluated the influence of PSMα3 on human insulin fibrillation in vitro, using a variety of experimental approaches in combination with computational molecular studies. First, it was shown that PSMα3 drastically inhibits the fibrillation of human insulin. The anti-fibrillation effect of PSMα3 was concentration-dependent and required a concentration ratio of PSMα3: insulin equal to or above 1 : 100. Molecular modelling revealed that PSMα3 most likely inhibits the production of insulin primary nuclei by competing for residues involved in its dimerization.
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Affiliation(s)
- Aleksandra Kalitnik
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Monika Szefczyk
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Alicja W Wojciechowska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Jakub W Wojciechowski
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Marlena Gąsior-Głogowska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Joanna Olesiak-Bańska
- Institute of Advanced Materials, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Małgorzata Kotulska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
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Marichal L, Bagnard L, Sire O, Vendrely C, Bruckert F, Weidenhaupt M. Phenol-soluble modulins form amyloids in contact with multiple surface chemistries. Biochim Biophys Acta Gen Subj 2023; 1867:130450. [PMID: 37640168 DOI: 10.1016/j.bbagen.2023.130450] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 08/31/2023]
Abstract
Functional amyloids are commonly produced by many microorganisms and their biological functions are numerous. Staphylococcus aureus can secrete a group of peptides named phenol-soluble modulins (PSMs) in their biofilm extracellular matrix. PSMs have been found inside biofilms both in their soluble form and assembled into amyloid structures. Yet, the actual biological function of these amyloids has been highly debated. Here, we assessed the ability of PSMs to form amyloids in contact with different abiotic surfaces to unravel a potential unknown bioadhesive and/or biofilm stabilization function. We combined surface plasmon resonance imaging, fluorescence aggregation kinetics, and FTIR spectroscopy in order to evaluate the PSM adsorption as well as amyloid formation properties in the presence of various surface chemistries. Overall, PSMs adsorb even on low-binding surfaces, making them highly adaptable adsorbants in the context of bioadhesion. Moreover, the PSM aggregation potential to form amyloid aggregates is not impacted by the presence of the surface chemistries tested. This versatility regarding adsorption and amyloid formation may imply a possible role of PSMs in biofilm adhesion and/or structure integrity.
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Affiliation(s)
- Laurent Marichal
- Université Grenoble Alpes, CNRS, Grenoble-INP LMGP, Grenoble F-38000, France
| | - Lucie Bagnard
- Université Grenoble Alpes, CNRS, Grenoble-INP LMGP, Grenoble F-38000, France
| | - Olivier Sire
- IRDL, UMR CNRS 6027, Université Bretagne Sud, Vannes, France
| | - Charlotte Vendrely
- Université Grenoble Alpes, CNRS, Grenoble-INP LMGP, Grenoble F-38000, France
| | - Franz Bruckert
- Université Grenoble Alpes, CNRS, Grenoble-INP LMGP, Grenoble F-38000, France
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Wang X, Uppu DSSM, Dickey SW, Burgin DJ, Otto M, Lee JC. Staphylococcus aureus delta toxin modulates both extracellular membrane vesicle biogenesis and amyloid formation. mBio 2023; 14:e0174823. [PMID: 37795985 PMCID: PMC10653798 DOI: 10.1128/mbio.01748-23] [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: 07/07/2023] [Accepted: 08/15/2023] [Indexed: 10/06/2023] Open
Abstract
IMPORTANCE Extracellular membrane vesicles (MVs) produced by Staphylococcus aureus in planktonic cultures encapsulate a diverse cargo of bacterial proteins, nucleic acids, and glycopolymers that are protected from destruction by external factors. δ-toxin, a member of the phenol soluble modulin family, was shown to be critical for MV biogenesis. Amyloid fibrils co-purified with MVs generated by virulent, community-acquired S. aureus strains, and fibril formation was dependent on expression of the S. aureus δ-toxin gene (hld). Mass spectrometry data confirmed that the amyloid fibrils were comprised of δ-toxin. Although S. aureus MVs were produced in vivo in a localized murine infection model, amyloid fibrils were not observed in the in vivo setting. Our findings provide critical insights into staphylococcal factors involved in MV biogenesis and amyloid formation.
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Affiliation(s)
- Xiaogang Wang
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Divakara SSM Uppu
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Seth W. Dickey
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine,University of Maryland, Bethesda, Maryland, USA
| | - Dylan J. Burgin
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA
| | - Jean C. Lee
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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7
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Rayan B, Barnea E, Khokhlov A, Upcher A, Landau M. Differential fibril morphologies and thermostability determine functional roles of Staphylococcus aureus PSMα1 and PSMα3. Front Mol Biosci 2023; 10:1184785. [PMID: 37469708 PMCID: PMC10353841 DOI: 10.3389/fmolb.2023.1184785] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 06/21/2023] [Indexed: 07/21/2023] Open
Abstract
Phenol-soluble modulins (PSMs) are virulent peptides secreted by staphylococci that undergo self-assembly into amyloid fibrils. This study focuses on Staphylococcus aureus PSMα1 and PSMα3, which share homologous sequences but exhibit distinct amyloid fibril structures. Upon subjecting PSMα1 to an 80°C heat shock, it fibrillates into cross-β structures, resulting in the loss of cytotoxic activity. Conversely, PSMα3 cross-α fibrils undergo reversible disaggregation upon heat shock, leading to the recovery of cytotoxicity. The differential thermostability probably arises from the presence of hydrogen bonds along the β-strands within the β-sheets of the cross-β fibrils. We propose that the breakdown of PSMα3 fibrils into soluble species, potentially co-aggregating with membrane lipids, is crucial for its toxic process and enables the reversible modulation of its biological activity under stress conditions. In contrast, the formation of robust and irreversible cross-β fibrils by PSMα1 corresponds to its role in biofilm stability. These findings emphasize how the unique fibril morphologies and thermostability of PSMα1 and PSMα3 shape their functional roles in various environments of S. aureus.
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Affiliation(s)
- Bader Rayan
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Eilon Barnea
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Alexander Khokhlov
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Alexander Upcher
- Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer-Sheva, Israel
| | - Meytal Landau
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
- Centre for Structural Systems Biology (CSSB), Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- The Center for Experimental Medicine, Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
- European Molecular Biology Laboratory (EMBL), Hamburg, Germany
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8
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Wang X, Uppu DS, Dickey SW, Burgin DJ, Otto M, Lee JC. Staphylococcus aureus Delta Toxin Modulates both Extracellular Membrane Vesicle Biogenesis and Amyloid Formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.533957. [PMID: 36993475 PMCID: PMC10055364 DOI: 10.1101/2023.03.23.533957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Staphylococcus aureus secretes phenol-soluble modulins (PSMs), a family of small, amphipathic, secreted peptides with multiple biologic activities. Community-acquired S. aureus strains produce high levels of PSMs in planktonic cultures, and PSM alpha peptides have been shown to augment the release of extracellular membrane vesicles (MVs). We observed that amyloids, aggregates of proteins characterized by a fibrillar morphology and stained with specific dyes, co-purified with MVs harvested from cell-free culture supernatants of community-acquired S. aureus strains. δ-toxin was a major component of amyloid fibrils that co-purified with strain LAC MVs, and δ-toxin promoted the production of MVs and amyloid fibrils in a dose-dependent manner. To determine whether MVs and amyloid fibrils were generated under in vivo conditions, we inoculated mice with S. aureus harvested from planktonic cultures. Bacterial MVs could be isolated and purified from lavage fluids recovered from infected animals. Although δ-toxin was the most abundant PSM in lavage fluids, amyloid fibrils could not be detected in these samples. Our findings expand our understanding of amyloid fibril formation in S. aureus cultures, reveal important roles of δ-toxin in amyloid fibril formation and MV biogenesis, and demonstrate that MVs are generated in vivo in a staphylococcal infection model. Importance Extracellular membrane vesicles (MVs) produced by Staphylococcus aureus in planktonic cultures encapsulate a diverse cargo of bacterial proteins, nucleic acids, and glycopolymers that are protected from destruction by external factors. δ-toxin, a member of the phenol soluble modulin family, was shown to be critical for MV biogenesis. Amyloid fibrils co-purified with MVs generated by virulent, community-acquired S. aureus strains, and fibril formation was dependent on expression of the S. aureus δ-toxin gene ( hld ). Mass spectrometry data confirmed that the amyloid fibrils were comprised of δ-toxin. Although S. aureus MVs were produced in vivo in a localized murine infection model, amyloid fibrils were not observed in the in vivo setting. Our findings provide critical insights into staphylococcal factors involved in MV biogenesis and amyloid formation.
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Li QQ, Chae HS, Kang OH, Kwon DY. Synergistic Antibacterial Activity with Conventional Antibiotics and Mechanism of Action of Shikonin against Methicillin-Resistant Staphylococcus aureus. Int J Mol Sci 2022; 23:ijms23147551. [PMID: 35886892 PMCID: PMC9322759 DOI: 10.3390/ijms23147551] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 07/01/2022] [Accepted: 07/06/2022] [Indexed: 12/11/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a troublesome pathogen that poses a global threat to public health. Shikonin (SKN) isolated from Lithospermum erythrorhizon (L. erythrorhizon) possesses a variety of biological activities. This study aims to explore the effect of the combined application of SKN and traditional antibiotics on the vitality of MRSA and the inherent antibacterial mechanism of SKN. The synergies between SKN and antibiotics against MRSA and its clinical strain have been demonstrated by the checkerboard assay and the time-kill assay. The effect of SKN on disrupting the integrity and permeability of bacterial cell membranes was verified by a nucleotide and protein leakage assay and a bacteriolysis assay. As determined by crystal violet staining, SKN inhibited the biofilm formation of clinical MRSA strains. The results of Western blot and qRT-PCR showed that SKN could inhibit the expression of proteins and genes related to drug resistance and S. aureus exotoxins. SKN inhibited the ability of RAW264.7 cells to release the pro-inflammatory cytokines TNF-α and IL-6, as measured by ELISA. Our findings suggest that SKN has the potential to be developed as a promising alternative for the treatment of MRSA infections.
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Affiliation(s)
- Qian-Qian Li
- Department of Oriental Pharmacy, College of Pharmacy and Wonkwang Oriental Medicines Research Institute, Wonkwang University, Iksan 54538, Jeonbuk, Korea;
| | - Hee-Sung Chae
- National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, Oxford, MS 38677, USA;
| | - Ok-Hwa Kang
- Department of Oriental Pharmacy, College of Pharmacy and Wonkwang Oriental Medicines Research Institute, Wonkwang University, Iksan 54538, Jeonbuk, Korea;
- Correspondence: (O.-H.K.); (D.-Y.K.); Tel.: +82-63-850-6802 (O.-H.K.)
| | - Dong-Yeul Kwon
- Department of Oriental Pharmacy, College of Pharmacy and Wonkwang Oriental Medicines Research Institute, Wonkwang University, Iksan 54538, Jeonbuk, Korea;
- Correspondence: (O.-H.K.); (D.-Y.K.); Tel.: +82-63-850-6802 (O.-H.K.)
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10
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Grando K, Nicastro LK, Tursi SA, De Anda J, Lee EY, Wong GCL, Tükel Ç. Phenol-Soluble Modulins From Staphylococcus aureus Biofilms Form Complexes With DNA to Drive Autoimmunity. Front Cell Infect Microbiol 2022; 12:884065. [PMID: 35646719 PMCID: PMC9131096 DOI: 10.3389/fcimb.2022.884065] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/04/2022] [Indexed: 12/15/2022] Open
Abstract
The bacterial amyloid curli, produced by Enterobacteriales including Salmonella species and Escherichia coli, is implicated in the pathogenesis of several complex autoimmune diseases. Curli binds to extracellular DNA, and these complexes drive autoimmunity via production of anti-double-stranded DNA autoantibodies. Here, we investigated immune activation by phenol-soluble modulins (PSMs), the amyloid proteins expressed by Staphylococcus species. We confirmed the amyloid nature of PSMs expressed by S. aureus using a novel specific amyloid stain, (E,E)-1-fluoro-2,5-bis(3-hydroxycarbonyl-4-hydroxy) styrylbenzene (FSB). Direct interaction of one of the S. aureus PSMs, PSMα3, with oligonucleotides promotes fibrillization of PSM amyloids and complex formation with bacterial DNA. Finally, utilizing a mouse model with an implanted mesh-associated S. aureus biofilm, we demonstrated that exposure to S. aureus biofilms for six weeks caused anti-double-stranded DNA autoantibody production in a PSM-dependent manner. Taken together, these results highlight how the presence of PSM-DNA complexes in S. aureus biofilms can induce autoimmune responses, and suggest an explanation for how bacterial infections trigger autoimmunity.
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Affiliation(s)
- Kaitlyn Grando
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Lauren K. Nicastro
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Sarah A. Tursi
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Jaime De Anda
- Department of Bioengineering, Department of Chemistry and Biochemistry, California Nano Systems Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Ernest Y. Lee
- Department of Bioengineering, Department of Chemistry and Biochemistry, California Nano Systems Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Gerard C. L. Wong
- Department of Bioengineering, Department of Chemistry and Biochemistry, California Nano Systems Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Çağla Tükel
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
- *Correspondence: Çağla Tükel,
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11
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Abstract
Revisiting underutilized classes of antibiotics is a pragmatic approach to the identification of alternative therapies for antimicrobial-resistant pathogens. To this end, we designed and screened a set of seven staphylococcal δ-toxin-inspired peptides (STIPs) for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, a pathogen-specific protease was leveraged to generate shorter peptides from these δ-toxin derivatives to expand the screen of putative antimicrobial peptides (AMPs) and to counterscreen against AMP inactivation. Remarkably, a 17-amino acid peptide based on the atypical δ-toxin sequence of Staphylococcus auricularis was discovered to possess an ability to kill MRSA and related pathogens. An alanine scan and series of rational substitutions improved AMP activity, and phenotypic assays characterized the STIPs’ ability to rapidly interact with and permeabilize the staphylococcal membrane without causing lysis on a commensurate timescale. Instead of rapid lysis, both l- and d-enantiomers of STIP3-29, an AMP with low micromolar activity, were observed to penetrate and accumulate within cells. Finally, we observed that STIP3-29 was capable of controlling MRSA infection in a three-dimensional skin infection model. Overall, the results suggest that this unconventional source of AMPs can provide promising candidates for further development as therapeutic agents. IMPORTANCE The continued emergence and global distribution of infections caused by antimicrobial-resistant pathogens fuel our perpetual need for new or alternative therapies. Here, we present the discovery and initial characterization of bacterial cell-penetrating AMPs that were based on a family of virulence factors. In contrast to the multitude of AMPs that are sourced from animals, these potential therapeutic molecules have not undergone extensive selection for their antimicrobial properties and have proven to be amenable to activity-optimizing modifications. The staphylococcal toxin-inspired peptides described here represent a source of AMPs that can kill common opportunistic pathogens, such as MRSA, and have the potential to be improved for application in medicine.
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