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Bradbury JD, Hodgkinson T, Thomas AM, Tanwar O, La Monica G, Rogga VV, Mackay LJ, Taylor EK, Gilbert K, Zhu Y, Sefton AY, Edwards AM, Gray-Hammerton CJ, Smith GR, Roberts PM, Walsh TR, Lanyon-Hogg T. Development of an inhibitor of the mutagenic SOS response that suppresses the evolution of quinolone antibiotic resistance. Chem Sci 2024; 15:9620-9629. [PMID: 38939155 PMCID: PMC11206376 DOI: 10.1039/d4sc00995a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 05/07/2024] [Indexed: 06/29/2024] Open
Abstract
Antimicrobial resistance (AMR) is a growing threat to health globally, with the potential to render numerous medical procedures so dangerous as to be impractical. There is therefore an urgent need for new molecules that function through novel mechanisms of action to combat AMR. The bacterial DNA-repair and SOS-response pathways promote survival of pathogens in infection settings and also activate hypermutation and resistance mechanisms, making these pathways attractive targets for new therapeutics. Small molecules, such as IMP-1700, potentiate DNA damage and inhibit the SOS response in methicillin-resistant S. aureus; however, understanding of the structure-activity relationship (SAR) of this series is lacking. We report here the first comprehensive SAR study of the IMP-1700 scaffold, identifying key pharmacophoric groups and delivering the most potent analogue reported to date, OXF-077. Furthermore, we demonstrate that as a potent inhibitor of the mutagenic SOS response, OXF-077 suppresses the rate of ciprofloxacin resistance emergence in S. aureus. This work supports SOS-response inhibitors as a novel means to combat AMR, and delivers OXF-077 as a tool molecule for future development.
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Affiliation(s)
- Jacob D Bradbury
- Department of Pharmacology, University of Oxford OX1 3QT UK
- Ineos Oxford Institute for Antimicrobial Research, Sir William Dunn School of Pathology, University of Oxford OX1 3RE UK
| | | | - Adam M Thomas
- Department of Pharmacology, University of Oxford OX1 3QT UK
| | | | - Gabriele La Monica
- Department of Pharmacology, University of Oxford OX1 3QT UK
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), University of Palermo 90128 Italy
| | | | - Luke J Mackay
- Department of Pharmacology, University of Oxford OX1 3QT UK
| | | | - Kiera Gilbert
- Department of Pharmacology, University of Oxford OX1 3QT UK
| | - Yihua Zhu
- Fred Hutchinson Cancer Center Seattle WA 98109-1024 USA
| | - Amber Y Sefton
- Department of Infectious Disease, Faculty of Medicine, Imperial College London W2 1NY UK
| | - Andrew M Edwards
- Department of Infectious Disease, Faculty of Medicine, Imperial College London W2 1NY UK
| | - Charlotte J Gray-Hammerton
- Ineos Oxford Institute for Antimicrobial Research, Sir William Dunn School of Pathology, University of Oxford OX1 3RE UK
| | | | - Paul M Roberts
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford OX1 3TA UK
| | - Timothy R Walsh
- Ineos Oxford Institute for Antimicrobial Research, Sir William Dunn School of Pathology, University of Oxford OX1 3RE UK
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Ahmed W, Li S, Liang M, Kang Y, Liu X, Gao C. Multifunctional Drug- and AuNRs-Loaded ROS-Responsive Selenium-Containing Polyurethane Nanofibers for Smart Wound Healing. ACS Biomater Sci Eng 2024; 10:3946-3957. [PMID: 38701357 DOI: 10.1021/acsbiomaterials.4c00363] [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] [Indexed: 05/05/2024]
Abstract
Elevated levels of ROS, bacterial infection, inflammation, and improper regeneration are the factors that need to be addressed simultaneously for achieving effective wound healing without scar formation. This study focuses on the fabrication of electrospun ROS-responsive selenium-containing polyurethane nanofibers incorporating deferoxamine mesylate (Def), indomethacin (Indo), and gold nanorods (AuNRs) as proangiogenesis, anti-inflammatory, and antibacterial agents for synchronized delivery to a full-thickness wound in vivo. The structure of the fabricated nanofibers was analyzed by various techniques. Toxicity was checked by CCK-8 and hemolytic assays. The efficiency of wound healing in vitro was verified by a transwell assay and cell scratch assay. The wound healing efficiency of the nanofibers was assayed in full-thickness wounds in a rat model. The multifunctional nanofibers had a porous structure, enhanced antioxidation, antibacterial activity, and promoted wound healing. They eradicated TNF-α and IL-6, increased IL-10 expression, and revealed the angiogenic potential by increased expression of HIF-1α, VEGF, and CD31.
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Affiliation(s)
- Wajiha Ahmed
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
| | - Shifen Li
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
| | - Min Liang
- Center for Healthcare Materials, Shaoxing Institute, Zhejiang University, Shaoxing 312099, China
| | - Yongyuan Kang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
| | - Xiaoqing Liu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310058, China
- Center for Healthcare Materials, Shaoxing Institute, Zhejiang University, Shaoxing 312099, China
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Ismail AS, Berryhill BA, Gil-Gil T, Manuel JA, Smith AP, Baquero F, Levin BR. The Tradeoffs Between Persistence and Mutation Rates at Sub-Inhibitory Antibiotic Concentrations in Staphylococcus aureus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.01.587561. [PMID: 38617265 PMCID: PMC11014548 DOI: 10.1101/2024.04.01.587561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The rational design of the antibiotic treatment of bacterial infections employs these drugs to reach concentrations that exceed the minimum needed to prevent the replication of the target bacteria. However, within a treated patient, spatial and physiological heterogeneity promotes antibiotic gradients such that the concentration of antibiotics at specific sites is below the minimum needed to inhibit bacterial growth. Here, we investigate the effects of sub-inhibitory antibiotic concentrations on three parameters central to bacterial infection and the success of antibiotic treatment, using in vitro experiments with Staphylococcus aureus and mathematical-computer simulation models. Our results, using drugs of six different classes, demonstrate that exposure to sub-inhibitory antibiotic concentrations not only alters the dynamics of bacterial growth but also increases the mutation rate to antibiotic resistance and decreases the rate of production of persister cells thereby reducing the persistence level. Understanding this trade-off between mutation rates and persistence levels resulting from sub-inhibitory antibiotic exposure is crucial for optimizing, and mitigating the failure of, antibiotic therapy.
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Affiliation(s)
| | - Brandon A. Berryhill
- Department of Biology, Emory University, Atlanta, Georgia, USA
- Program in Microbiology and Molecular Genetics, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Teresa Gil-Gil
- Department of Biology, Emory University, Atlanta, Georgia, USA
| | | | - Andrew P. Smith
- Department of Biology, Emory University, Atlanta, Georgia, USA
| | - Fernando Baquero
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, and Centro de Investigación Médica en Red, Epidemiología y Salud Pública (CIBERESP) Madrid, Spain
| | - Bruce R. Levin
- Department of Biology, Emory University, Atlanta, Georgia, USA
- Emory Antibiotic Resistance Center, Emory University, Atlanta, Georgia, USA
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Chapman JE, George SE, Wolz C, Olson ME. Biofilms: A developmental niche for vancomycin-intermediate Staphylococcus aureus. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2024; 117:105545. [PMID: 38160879 DOI: 10.1016/j.meegid.2023.105545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/14/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024]
Abstract
Staphylococcus aureus are gram-positive bacteria responsible for a wide array of diseases, ranging from skin and soft tissue infections to more chronic illnesses such as toxic shock syndrome, osteomyelitis, and endocarditis. Vancomycin is currently one of the most effective antibiotics available in treating patients infected with methicillin-resistant S. aureus (MRSA), however the emergence of vancomycin-resistant S. aureus (VRSA), and more commonly vancomycin-intermediate S. aureus (VISA), threaten the future efficacy of vancomycin. Intermediate resistance to vancomycin occurs due to mutations within the loci of Staphylococcal genes involved in cell wall formation such as rpoB, graS, and yycG. We hypothesized the VISA phenotype may also arise as a result of the natural stress occurring within S. aureus biofilms, and that this phenomenon is mediated by the RecA/SOS response. Wildtype and recA null mutant/lexAG94E strains of S. aureus biofilms were established in biofilm microtiter assays or planktonic cultures with or without the addition of sub-inhibitory concentrations of vancomycin (0.063 mg/l - 0.25 mg/L ciprofloxacin, 0.5 mg/l vancomycin). Efficiency of plating techniques were used to quantify the subpopulation of biofilm-derived S. aureus cells that developed vancomycin-intermediate resistance. The results indicated that a greater subpopulation of cells from wildtype biofilms (4.16 × 102 CFUs) emerged from intermediate-resistant concentrations of vancomycin (4 μg/ml) compared with the planktonic counterpart (1.53 × 101 CFUs). Wildtype biofilms (4.16 × 102 CFUs) also exhibited greater resistance to intermediate-resistant concentrations of vancomycin compared with strains deficient in the recA null mutant (8.15 × 101 CFUs) and lexA genes (8.00 × 101 CFUs). While the VISA phenotype would be an unintended consequence of genetic diversity and potentially gene transfer in the biofilm setting, it demonstrates that mutations occurring within biofilms allow for S. aureus to adapt to new environments, including the presence of widely used antibiotics.
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Affiliation(s)
- Jenelle E Chapman
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, USA
| | - Shilpa E George
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Germany
| | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Germany
| | - Michael E Olson
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, USA.
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Ledger EVK, Lau K, Tate EW, Edwards AM. XerC Is Required for the Repair of Antibiotic- and Immune-Mediated DNA Damage in Staphylococcus aureus. Antimicrob Agents Chemother 2023; 67:e0120622. [PMID: 36802166 PMCID: PMC10019262 DOI: 10.1128/aac.01206-22] [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] [Indexed: 02/23/2023] Open
Abstract
To survive in the host environment, pathogenic bacteria need to be able to repair DNA damage caused by both antibiotics and the immune system. The SOS response is a key bacterial pathway to repair DNA double-strand breaks and may therefore be a good target for novel therapeutics to sensitize bacteria to antibiotics and the immune response. However, the genes required for the SOS response in Staphylococcus aureus have not been fully established. Therefore, we carried out a screen of mutants involved in various DNA repair pathways to understand which were required for induction of the SOS response. This led to the identification of 16 genes that may play a role in SOS response induction and, of these, 3 that affected the susceptibility of S. aureus to ciprofloxacin. Further characterization revealed that, in addition to ciprofloxacin, loss of the tyrosine recombinase XerC increased the susceptibility of S. aureus to various classes of antibiotics, as well as to host immune defenses. Therefore, the inhibition of XerC may be a viable therapeutic approach to sensitize S. aureus to both antibiotics and the immune response.
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Affiliation(s)
- Elizabeth V. K. Ledger
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Katie Lau
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Edward W. Tate
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom
| | - Andrew M. Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
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Wilkinson M, Wilkinson OJ, Feyerherm C, Fletcher EE, Wigley DB, Dillingham MS. Structures of RecBCD in complex with phage-encoded inhibitor proteins reveal distinctive strategies for evasion of a bacterial immunity hub. eLife 2022; 11:e83409. [PMID: 36533901 PMCID: PMC9836394 DOI: 10.7554/elife.83409] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/18/2022] [Indexed: 12/23/2022] Open
Abstract
Following infection of bacterial cells, bacteriophage modulate double-stranded DNA break repair pathways to protect themselves from host immunity systems and prioritise their own recombinases. Here, we present biochemical and structural analysis of two phage proteins, gp5.9 and Abc2, which target the DNA break resection complex RecBCD. These exemplify two contrasting mechanisms for control of DNA break repair in which the RecBCD complex is either inhibited or co-opted for the benefit of the invading phage. Gp5.9 completely inhibits RecBCD by preventing it from binding to DNA. The RecBCD-gp5.9 structure shows that gp5.9 acts by substrate mimicry, binding predominantly to the RecB arm domain and competing sterically for the DNA binding site. Gp5.9 adopts a parallel coiled-coil architecture that is unprecedented for a natural DNA mimic protein. In contrast, binding of Abc2 does not substantially affect the biochemical activities of isolated RecBCD. The RecBCD-Abc2 structure shows that Abc2 binds to the Chi-recognition domains of the RecC subunit in a position that might enable it to mediate the loading of phage recombinases onto its single-stranded DNA products.
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Affiliation(s)
- Martin Wilkinson
- Section of Structural Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College LondonLondonUnited Kingdom
| | - Oliver J Wilkinson
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
| | - Connie Feyerherm
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
| | - Emma E Fletcher
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
| | - Dale B Wigley
- Section of Structural Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College LondonLondonUnited Kingdom
| | - Mark S Dillingham
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
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7
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Revitt‐Mills SA, Wright EK, Vereker M, O'Flaherty C, McPherson F, Dawson C, van Oijen AM, Robinson A. Defects in DNA double‐strand break repair resensitize antibiotic‐resistant
Escherichia coli
to multiple bactericidal antibiotics. Microbiologyopen 2022; 11:e1316. [PMCID: PMC9500592 DOI: 10.1002/mbo3.1316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 09/03/2022] [Accepted: 09/03/2022] [Indexed: 11/11/2022] Open
Affiliation(s)
- Sarah A. Revitt‐Mills
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Elizabeth K. Wright
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Madaline Vereker
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Callum O'Flaherty
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Fairley McPherson
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Catherine Dawson
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Antoine M. van Oijen
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
| | - Andrew Robinson
- School of Chemistry and Molecular Bioscience, Molecular Horizons Institute University of Wollongong Wollongong New South Wales Australia
- Illawarra Health and Medical Research Institute Wollongong New South Wales Australia
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8
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Turgimbayeva A, Zein U, Zharkov DO, Ramankulov Y, Saparbaev M, Abeldenov S. Cloning and characterization of the major AP endonuclease from Staphylococcus aureus. DNA Repair (Amst) 2022; 119:103390. [DOI: 10.1016/j.dnarep.2022.103390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/19/2022] [Accepted: 08/20/2022] [Indexed: 11/03/2022]
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Abstract
Staphylococcus aureus is a common cause of both superficial and invasive infections of humans and animals. Despite a potent host response and apparently appropriate antibiotic therapy, staphylococcal infections frequently become chronic or recurrent, demonstrating a remarkable ability of S. aureus to withstand the hostile host environment. There is growing evidence that staphylococcal DNA repair makes important contributions to the survival of the pathogen in host tissues, as well as promoting the emergence of mutants that resist host defenses and antibiotics. While much of what we know about DNA repair in S. aureus is inferred from studies with model organisms, the roles of specific repair mechanisms in infection are becoming clear and differences with Bacillus subtilis and Escherichia coli have been identified. Furthermore, there is growing interest in staphylococcal DNA repair as a target for novel therapeutics that sensitize the pathogen to host defenses and antibiotics. In this review, we discuss what is known about staphylococcal DNA repair and its role in infection, examine how repair in S. aureus is similar to, or differs from, repair in well-characterized model organisms, and assess the potential of staphylococcal DNA repair as a novel therapeutic target.
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10
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Fei Y, Huang Q, Hu Z, Yang X, Yang B, Liu S. Biomimetic Cerium Oxide Loaded Gelatin PCL Nanosystems for Wound Dressing on Cutaneous Care Management of Multidrug-Resistant Bacterial Wound Healing. J CLUST SCI 2021. [DOI: 10.1007/s10876-020-01866-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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11
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RexAB promotes the survival of Staphylococcus aureus exposed to multiple classes of antibiotics. Antimicrob Agents Chemother 2021; 65:e0059421. [PMID: 34310219 PMCID: PMC8448105 DOI: 10.1128/aac.00594-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Antibiotics inhibit essential bacterial processes, resulting in arrest of growth and, in some cases, cell death. Many antibiotics are also reported to trigger endogenous production of reactive oxygen species (ROS), which damage DNA, leading to induction of the mutagenic SOS response associated with the emergence of drug resistance. However, the type of DNA damage that arises and how this triggers the SOS response are largely unclear. We found that several different classes of antibiotic triggered dose-dependent induction of the SOS response in Staphylococcus aureus, indicative of DNA damage, including some bacteriostatic drugs. The SOS response was heterogenous and varied in magnitude between strains and antibiotics. However, in many cases, full induction of the SOS response was dependent upon the RexAB helicase/nuclease complex, which processes DNA double-strand breaks to produce single-stranded DNA and facilitate RecA nucleoprotein filament formation. The importance of RexAB in repair of DNA was confirmed by measuring bacterial survival during antibiotic exposure, with most drugs having significantly greater bactericidal activity against rexB mutants than against wild-type strains. For some, but not all, antibiotics there was no difference in bactericidal activity between wild type and rexB mutant under anaerobic conditions, indicative of a role for reactive oxygen species in mediating DNA damage. Taken together, this work confirms previous observations that several classes of antibiotics cause DNA damage in S. aureus and extends them by showing that processing of DNA double-strand breaks by RexAB is a major trigger of the mutagenic SOS response and promotes bacterial survival.
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12
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DNA glycosylases for 8-oxoguanine repair in Staphylococcus aureus. DNA Repair (Amst) 2021; 105:103160. [PMID: 34192601 DOI: 10.1016/j.dnarep.2021.103160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/20/2022]
Abstract
GO system is part of base excision DNA repair and is required for the correct repair of 8-oxoguanine (8-oxoG), one of the most abundant oxidative lesions. Due to the ability of 8-oxoG to mispair with A, this base is highly mutagenic, and its repair requires two enzymes: Fpg that removes 8-oxoG from 8-oxoG:C pairs, and MutY that excises the normal A from 8-oxoG:A mispairs. Here we characterize the properties of putative GO system DNA glycosylases from Staphylococcus aureus, an important human opportunistic pathogen that causes hospital infections and presents a serious health concern due to quick spread of antibiotic-resistant strains. In addition to Fpg and MutY from the reference NCTC 8325 strain (SauFpg1 and SauMutY), we have also studied an Fpg homolog from a multidrug-resistant C0673 isolate (SauFpg2), which is different from SauFpg1 in its sequence. Both SauFpg enzymes showed the highest activity at pH 7.0-9.0 and NaCl concentrations 25-75 mM (SauFpg1) or 50-100 mM (SauFpg2), whereas SauMutY was active at a broad pH range and had a salt optimum at ∼75 mM NaCl. Both SauFpg1 and SauFpg2 bound and cleaved duplexes containing 8-oxoG, 5-hydroxyuracil, 5,6-dihydrouracil or apurinic/apyrimidinic site paired with C, T, or G, but not with A. For SauFpg1 and SauFpg2, 8-oxoG was the best substrate tested, and 5,6-dihydrouracil was the worst one. SauMutY efficiently excised adenine from duplex substrates containing A:8-oxoG or A:G pairs. SauFpg enzymes were readily trapped on DNA by NaBH4 treatment, indicating formation of a Schiff base reaction intermediate. Surprisingly, SauMutY was also trapped significantly better than its E. coli homolog. All three S. aureus GO glycosylases drastically reduced spontaneous mutagenesis when expressed in an fpg mutY E. coli double mutant. Overall, we conclude that S. aureus possesses an active GO system, which could possibly be targeted for sensitization of this pathogen to oxidative stress.
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13
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Targeting the bacterial SOS response for new antimicrobial agents: drug targets, molecular mechanisms and inhibitors. Future Med Chem 2021; 13:143-155. [PMID: 33410707 DOI: 10.4155/fmc-2020-0310] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Antimicrobial resistance is a pressing threat to global health, with multidrug-resistant pathogens becoming increasingly prevalent. The bacterial SOS pathway functions in response to DNA damage that occurs during infection, initiating several pro-survival and resistance mechanisms, such as DNA repair and hypermutation. This makes SOS pathway components potential targets that may combat drug-resistant pathogens and decrease resistance emergence. This review discusses the mechanism of the SOS pathway; the structure and function of potential targets AddAB, RecBCD, RecA and LexA; and efforts to develop selective small-molecule inhibitors of these proteins. These inhibitors may serve as valuable tools for target validation and provide the foundations for desperately needed novel antibacterial therapeutics.
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14
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Ha KP, Clarke RS, Kim GL, Brittan JL, Rowley JE, Mavridou DAI, Parker D, Clarke TB, Nobbs AH, Edwards AM. Staphylococcal DNA Repair Is Required for Infection. mBio 2020; 11:e02288-20. [PMID: 33203752 PMCID: PMC7683395 DOI: 10.1128/mbio.02288-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/14/2020] [Indexed: 01/07/2023] Open
Abstract
To cause infection, Staphylococcus aureus must withstand damage caused by host immune defenses. However, the mechanisms by which staphylococcal DNA is damaged and repaired during infection are poorly understood. Using a panel of transposon mutants, we identified the rexBA operon as being important for the survival of Staphylococcus aureus in whole human blood. Mutants lacking rexB were also attenuated for virulence in murine models of both systemic and skin infections. We then demonstrated that RexAB is a member of the AddAB family of helicase/nuclease complexes responsible for initiating the repair of DNA double-strand breaks. Using a fluorescent reporter system, we were able to show that neutrophils cause staphylococcal DNA double-strand breaks through reactive oxygen species (ROS) generated by the respiratory burst, which are repaired by RexAB, leading to the induction of the mutagenic SOS response. We found that RexAB homologues in Enterococcus faecalis and Streptococcus gordonii also promoted the survival of these pathogens in human blood, suggesting that DNA double-strand break repair is required for Gram-positive bacteria to survive in host tissues. Together, these data demonstrate that DNA is a target of host immune cells, leading to double-strand breaks, and that the repair of this damage by an AddAB-family enzyme enables the survival of Gram-positive pathogens during infection.IMPORTANCE To cause infection, bacteria must survive attack by the host immune system. For many bacteria, including the major human pathogen Staphylococcus aureus, the greatest threat is posed by neutrophils. These immune cells ingest the invading organisms and try to kill them with a cocktail of chemicals that includes reactive oxygen species (ROS). The ability of S. aureus to survive this attack is crucial for the progression of infection. However, it was not clear how the ROS damaged S. aureus and how the bacterium repaired this damage. In this work, we show that ROS cause breaks in the staphylococcal DNA, which must be repaired by a two-protein complex known as RexAB; otherwise, the bacterium is killed, and it cannot sustain infection. This provides information on the type of damage that neutrophils cause S. aureus and the mechanism by which this damage is repaired, enabling infection.
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Affiliation(s)
- Kam Pou Ha
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Rebecca S Clarke
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Gyu-Lee Kim
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Jane L Brittan
- Bristol Dental School, University of Bristol, Bristol, United Kingdom
| | - Jessica E Rowley
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Despoina A I Mavridou
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA
| | - Dane Parker
- Department of Pathology, Immunology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Thomas B Clarke
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Angela H Nobbs
- Bristol Dental School, University of Bristol, Bristol, United Kingdom
| | - Andrew M Edwards
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
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