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Nguyen A, Roy JJS, Kim JH, Yun KH, Lee W, Kim KK, Kim T, Chaurasia AK. Repeated Exposure of Vancomycin to Vancomycin-Susceptible Staphylococcus aureus (VSSA) Parent Emerged VISA and VRSA Strains with Enhanced Virulence Potentials. J Microbiol 2024:10.1007/s12275-024-00139-8. [PMID: 38814539 DOI: 10.1007/s12275-024-00139-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 04/18/2024] [Accepted: 04/21/2024] [Indexed: 05/31/2024]
Abstract
The emergence of resistance against the last-resort antibiotic vancomycin in staphylococcal infections is a serious concern for human health. Although various drug-resistant pathogens of diverse genetic backgrounds show higher virulence potential, the underlying mechanism behind this is not yet clear due to variability in their genetic dispositions. In this study, we investigated the correlation between resistance and virulence in adaptively evolved isogenic strains. The vancomycin-susceptible Staphylococcus aureus USA300 was exposed to various concentrations of vancomycin repeatedly as a mimic of the clinical regimen to obtain mutation(s)-accrued-clonally-selected (MACS) strains. The phenotypic analyses followed by expression of the representative genes responsible for virulence and resistance of MACS strains were investigated. MACS strains obtained under 2 and 8 µg/ml vancomycin, named Van2 and Van8, respectively; showed enhanced vancomycin minimal inhibitory concentrations (MIC) to 4 and 16 µg/ml, respectively. The cell adhesion and invasion of MACS strains increased in proportion to their MICs. The correlation between resistance and virulence potential was partially explained by the differential expression of genes known to be involved in both virulence and resistance in MACS strains compared to parent S. aureus USA300. Repeated treatment of vancomycin against vancomycin-susceptible S. aureus (VSSA) leads to the emergence of vancomycin-resistant strains with variable levels of enhanced virulence potentials.
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Affiliation(s)
- An Nguyen
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea
- Department of Biophysics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - J Jean Sophy Roy
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea
| | - Ji-Hoon Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Kyung-Hee Yun
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea
| | - Wonsik Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.
- Department of Biophysics, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
| | - Truc Kim
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.
| | - Akhilesh Kumar Chaurasia
- Department of Precision Medicine, Graduate School of Basic Medical Science (GSBMS), Institute for Antimicrobial Resistance Research and Therapeutics, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.
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2
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Sabino YNV, de Araújo Domingues KC, O'Connor PM, Marques PH, Santos EH, Tótola MR, Abreu LM, de Queiroz MV, Cotter PD, Mantovani HC. Bacillus velezensis iturins inhibit the hemolytic activity of Staphylococcus aureus. Sci Rep 2024; 14:9469. [PMID: 38658583 PMCID: PMC11043418 DOI: 10.1038/s41598-024-58973-0] [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: 09/08/2023] [Accepted: 04/05/2024] [Indexed: 04/26/2024] Open
Abstract
Bovine mastitis caused by S. aureus has a major economic impact on the dairy sector. With the crucial need for new therapies, anti-virulence strategies have gained attention as alternatives to antibiotics. Here we aimed to identify novel compounds that inhibit the production/activity of hemolysins, a virulence factor of S. aureus associated with mastitis severity. We screened Bacillus strains obtained from diverse sources for compounds showing anti-hemolytic activity. Our results demonstrate that lipopeptides produced by Bacillus spp. completely prevented the hemolytic activity of S. aureus at certain concentrations. Following purification, both iturins, fengycins, and surfactins were able to reduce hemolysis caused by S. aureus, with iturins showing the highest anti-hemolytic activity (up to 76% reduction). The lipopeptides showed an effect at the post-translational level. Molecular docking simulations demonstrated that these compounds can bind to hemolysin, possibly interfering with enzyme action. Lastly, molecular dynamics analysis indicated general stability of important residues for hemolysin activity as well as the presence of hydrogen bonds between iturins and these residues, with longevous interactions. Our data reveals, for the first time, an anti-hemolytic activity of lipopeptides and highlights the potential application of iturins as an anti-virulence therapy to control bovine mastitis caused by S. aureus.
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Affiliation(s)
| | | | | | - Pedro Henrique Marques
- Department of Microbiology, Immunology and Parasitology, Federal University of Triângulo Mineiro, Uberaba, MG, Brazil
| | - Eduardo Horta Santos
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | | | | | - Paul D Cotter
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Cork, Ireland
- APC Microbiome Ireland, Cork, Ireland
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Millette G, Séguin DL, Isabelle C, Chamberland S, Lucier JF, Rodrigue S, Cantin AM, Malouin F. Staphylococcus aureus Small-Colony Variants from Airways of Adult Cystic Fibrosis Patients as Precursors of Adaptive Antibiotic-Resistant Mutations. Antibiotics (Basel) 2023; 12:1069. [PMID: 37370388 PMCID: PMC10294822 DOI: 10.3390/antibiotics12061069] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
Prototypic Staphylococcus aureus and their small-colony variants (SCVs) are predominant in cystic fibrosis (CF), but the interdependence of these phenotypes is poorly understood. We characterized S. aureus isolates from adult CF patients over several years. Of 18 S. aureus-positive patients (58%), 13 (72%) were positive for SCVs. Characterization included genotyping, SCCmec types, auxotrophy, biofilm production, antibiotic susceptibilities and tolerance, and resistance acquisition rates. Whole-genome sequencing revealed that several patients were colonized with prototypical and SCV-related clones. Some clonal pairs showed acquisition of aminoglycoside resistance that was not explained by aminoglycoside-modifying enzymes, suggesting a mutation-based process. The characteristics of SCVs that could play a role in resistance acquisition were thus investigated further. For instance, SCV isolates produced more biofilm (p < 0.05) and showed a higher survival rate upon exposure to ciprofloxacin and vancomycin compared to their prototypic associated clones. SCVs also developed spontaneous rifampicin resistance mutations at a higher frequency. Accordingly, a laboratory-derived SCV (ΔhemB) acquired resistance to ciprofloxacin and gentamicin faster than its parent counterpart after serial passages in the presence of sub-inhibitory concentrations of antibiotics. These results suggest a role for SCVs in the establishment of persistent antibiotic-resistant clones in adult CF patients.
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Affiliation(s)
- Guillaume Millette
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - David Lalonde Séguin
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Charles Isabelle
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Suzanne Chamberland
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Jean-François Lucier
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Sébastien Rodrigue
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - André M. Cantin
- Service de Pneumologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
| | - François Malouin
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
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4
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da Luz BSR, de Rezende Rodovalho V, Nicolas A, Chabelskaya S, Jardin J, Briard-Bion V, Le Loir Y, de Carvalho Azevedo VA, Guédon É. Impact of Environmental Conditions on the Protein Content of Staphylococcus aureus and Its Derived Extracellular Vesicles. Microorganisms 2022; 10:microorganisms10091808. [PMID: 36144410 PMCID: PMC9506334 DOI: 10.3390/microorganisms10091808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/01/2022] [Accepted: 09/04/2022] [Indexed: 12/03/2022] Open
Abstract
Staphylococcus aureus, a major opportunistic pathogen in humans, produces extracellular vesicles (EVs) that are involved in cellular communication, the delivery of virulence factors, and modulation of the host immune system response. However, to date, the impact of culture conditions on the physicochemical and functional properties of S. aureus EVs is still largely unexplored. Here, we use a proteomic approach to provide a complete protein characterization of S. aureus HG003, a NCTC8325 derivative strain and its derived EVs under four growth conditions: early- and late-stationary growth phases, and in the absence and presence of a sub-inhibitory concentration of vancomycin. The HG003 EV protein composition in terms of subcellular localization, COG and KEGG categories, as well as their relative abundance are modulated by the environment and differs from that of whole-cell (WC). Moreover, the environmental conditions that were tested had a more pronounced impact on the EV protein composition when compared to the WC, supporting the existence of mechanisms for the selective packing of EV cargo. This study provides the first general picture of the impact of different growth conditions in the proteome of S. aureus EVs and its producing-cells and paves the way for future studies to understand better S. aureus EV production, composition, and roles.
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Affiliation(s)
- Brenda Silva Rosa da Luz
- INRAE, Institut Agro, STLO, F-35000 Rennes, France
- Laboratory of Cellular and Molecular Genetics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Vinícius de Rezende Rodovalho
- INRAE, Institut Agro, STLO, F-35000 Rennes, France
- Laboratory of Cellular and Molecular Genetics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
| | | | - Svetlana Chabelskaya
- BRM (Bacterial Regulatory RNAs and Medicine) UMR_S 1230, Inserm 1230, University of Rennes 1, 35000 Rennes, France
| | | | | | - Yves Le Loir
- INRAE, Institut Agro, STLO, F-35000 Rennes, France
| | - Vasco Ariston de Carvalho Azevedo
- Laboratory of Cellular and Molecular Genetics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Éric Guédon
- INRAE, Institut Agro, STLO, F-35000 Rennes, France
- Correspondence:
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Yuan G, Li P, Xu X, Li P, Zhong Q, He S, Yi H, Yi W, Guan Y, Wen ZT. Azalomycin F 5a Eradicates Staphylococcus aureus Biofilm by Rapidly Penetrating and Subsequently Inducing Cell Lysis. Int J Mol Sci 2020; 21:ijms21030862. [PMID: 32013221 PMCID: PMC7036916 DOI: 10.3390/ijms21030862] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/24/2020] [Accepted: 01/28/2020] [Indexed: 12/14/2022] Open
Abstract
Antimicrobial resistance has emerged as a serious threat to public health. Bacterial biofilm, as a natural lifestyle, is a major contributor to resistance to antimicrobials. Azalomycin F5a, a natural guanidine-containing polyhydroxy macrolide, has remarkable activities against Gram-positive bacteria, including Staphylococcus aureus, a major causative agent of hospital-acquired infections. To further evaluate its potential to be developed as a new antimicrobial agent, its influence on S. aureus biofilm formation was evaluated using the crystal violet method, and then its eradication effect against mature biofilms was determined by confocal laser scanning microscopy, the drop plate method, and regrowth experiments. The results showed that azalomycin F5a could significantly inhibit S. aureus biofilm formation, and such effects were concentration dependent. In addition, it can also eradicate S. aureus mature biofilms with the minimum biofilm eradication concentration of 32.0 μg/mL. As extracellular deoxyribonucleic acid (eDNA) plays important roles in the structural integrity of bacterial biofilm, its influence on the eDNA release in S. aureus biofilm was further analyzed using gel electrophoresis. Combined with our previous works, these results indicate that azalomycin F5a could rapidly penetrate biofilm and causes damages to the cell membrane, leading to an increase in DNase release and eventually eradicating S. aureus biofilm.
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Affiliation(s)
- Ganjun Yuan
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
- Department of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA 70119, USA
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70119, USA
- Correspondence: (G.Y.); (Z.T.W.); Tel.: +86-791-83813459 (G.Y.); +1-504-9418465 (Z.T.W.)
| | - Pingyi Li
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Xuejie Xu
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Peibo Li
- School of Life Sciences, Sun Yat-sen University, 135 Xingang Road, Guangzhou 510275, China
| | - Qiwang Zhong
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Su He
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Houqin Yi
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Wenfang Yi
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Yingying Guan
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China; (P.L.); (Q.Z.)
| | - Zezhang Tom Wen
- Department of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA 70119, USA
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70119, USA
- Correspondence: (G.Y.); (Z.T.W.); Tel.: +86-791-83813459 (G.Y.); +1-504-9418465 (Z.T.W.)
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Supa-Amornkul S, Mongkolsuk P, Summpunn P, Chaiyakunvat P, Navaratdusit W, Jiarpinitnun C, Chaturongakul S. Alternative Sigma Factor B in Bovine Mastitis-Causing Staphylococcus aureus: Characterization of Its Role in Biofilm Formation, Resistance to Hydrogen Peroxide Stress, Regulon Members. Front Microbiol 2019; 10:2493. [PMID: 31787937 PMCID: PMC6853994 DOI: 10.3389/fmicb.2019.02493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/16/2019] [Indexed: 12/24/2022] Open
Abstract
This study examines treatments of the bacterial pathogen Staphylococcus aureus, namely, in the context of its being a major cause of subclinical bovine mastitis. Such infections caused by S. aureus among dairy cows are difficult to detect and can easily become chronic, leading to reduced productivity and large losses for dairy manufacturers. In this study, the role of alternative sigma factor B (σB), which has been shown to be a global regulator for S. aureus infections, was explored in a mastitis-causing S. aureus strain, RF122. For comparison with the wild-type strain, a sigB null (ΔsigB) mutant was constructed and analyzed for its phenotypes and transcriptome. Our study found that σB is essential for biofilm formation as the ΔsigB mutant strain produced significantly less biofilm than did the wild-type strain at 48 h. σB is involved in response to H2O2 stress. However, σB plays a minor or no role in resistance to antiseptics (e.g., povidone-iodine and chlorhexidine), resistance to tested antibiotics, hemolysin activity, and invasion ability. RNA sequencing identified 225 σB-dependent genes, of which 171 are positively regulated and 54 are negatively regulated. The identified genes are involved in stress response, pathogenesis, and metabolic mechanisms. Quantitative TaqMan RT-PCR was performed to verify the RNA sequencing results; i.e., σB is a positive regulator for asp23, sarA, katA, yabJ, sodA, SAB2006c, and nrdD expressions. In the RF122 strain, σB plays a role in biofilm formation, general stress response (e.g., H2O2), and regulation of virulence factors and virulence-associated genes.
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Affiliation(s)
- Sirirak Supa-Amornkul
- Mahidol International Dental School, Faculty of Dentistry, Mahidol University, Bangkok, Thailand
| | - Paninee Mongkolsuk
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Pijug Summpunn
- Food Technology and Innovation Research Center of Excellence, School of Agricultural Technology, Walailak University, Nakhon Si Thammarat, Thailand
| | - Pongkorn Chaiyakunvat
- Department of Chemistry and Center for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Warisara Navaratdusit
- Department of Chemistry and Center for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Chutima Jiarpinitnun
- Department of Chemistry and Center for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Soraya Chaturongakul
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand
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7
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Olwal CO, Ang'ienda PO, Ochiel DO. Alternative sigma factor B (σ B) and catalase enzyme contribute to Staphylococcus epidermidis biofilm's tolerance against physico-chemical disinfection. Sci Rep 2019; 9:5355. [PMID: 30926870 PMCID: PMC6440968 DOI: 10.1038/s41598-019-41797-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Accepted: 03/18/2019] [Indexed: 12/11/2022] Open
Abstract
Staphylococcus epidermidis is the predominant cause of recalcitrant biofilm-associated infections, which are often highly resistant to antibiotics. Thus, the use of physico-chemical agents for disinfection offers a more effective approach to the control of S. epidermidis biofilm infections. However, the underlying tolerance mechanisms employed by S. epidermidis biofilm against these physico-chemical disinfectants remain largely unknown. The expression of a σB-dependent gene, alkaline shock protein 23 (asp23) and catalase activity by S. epidermidis biofilm and planktonic cells exposed to heat (50 °C), 0.8 M sodium chloride (NaCl), 5 mM sodium hypochlorite (NaOCl) or 50 μM hydrogen peroxide (H2O2) for 60 minutes were compared. Significantly higher asp23 expression levels were observed in biofilms exposed to 50 °C, 5 mM NaOCl or 50 μM H2O2 compared to the corresponding planktonic cells (p < 0.05). Conversely, asp23 expression levels in biofilm and planktonic cells exposed to 0.8 M NaCl were not significantly different (p > 0.05). Further, biofilms exposed to 50 °C, 0.8 M NaCl, 5 mM NaOCl or 50 μM H2O2 exhibited significantly higher catalase activity than the planktonic cells (p < 0.05). These results suggest that activities of σB and catalase may be involved in the tolerance of S. epidermidis biofilm against physico-chemical disinfection.
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8
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Kim CY, Lee M, Lee K, Yoon SS, Lee I. Network-based genetic investigation of virulence-associated phenotypes in methicillin-resistant Staphylococcus aureus. Sci Rep 2018; 8:10796. [PMID: 30018396 PMCID: PMC6050336 DOI: 10.1038/s41598-018-29120-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 07/02/2018] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus is a gram-positive bacterium that causes a wide range of infections. Recently, the spread of methicillin-resistant S. aureus (MRSA) strains has seriously reduced antibiotic treatment options. Anti-virulence strategies, the objective of which is to target the virulence instead of the viability of the pathogen, have become widely accepted as a means of avoiding the emergence of new antibiotic-resistant strains. To increase the number of anti-virulence therapeutic options, it is necessary to identify as many novel virulence-associated genes as possible in MRSA. Co-functional networks have proved useful for mapping gene-to-phenotype associations in various organisms. Herein, we present StaphNet (www.inetbio.org/staphnet), a genome-scale co-functional network for an MRSA strain, S. aureus subsp. USA300_FPR3757. StaphNet, which was constructed by the integration of seven distinct types of genomics data within a Bayesian statistics framework, covers approximately 94% of the coding genome with a high degree of accuracy. We implemented a companion web server for network-based gene prioritization of the phenotypes of 31 different S. aureus strains. We demonstrated that StaphNet can effectively identify genes for virulence-associated phenotypes in MRSA. These results suggest that StaphNet can facilitate target discovery for the development of anti-virulence drugs to treat MRSA infection.
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Affiliation(s)
- Chan Yeong Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Muyoung Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Keehoon Lee
- Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Sang Sun Yoon
- Department of Microbiology and Immunology, Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Insuk Lee
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Korea.
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9
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Miller HK, Burda WN, Carroll RK, Shaw LN. Identification of a unique transcriptional architecture for the sigS operon in Staphylococcus aureus. FEMS Microbiol Lett 2018; 365:4983123. [PMID: 29688345 DOI: 10.1093/femsle/fny108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 04/21/2018] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus possess three alternative σ factors, including a lone extracytoplasmic function σ factor, σS. Our group previously identified and characterized this element, mapping three sigS promoters, demonstrating its inducibility during stress and virulence inducing conditions and demonstrating a role for this factor in disease causation. In the present study, we identify a fourth promoter of the sigS operon, termed P4, located in a unique position internal to the sigS coding region. Transcriptional profiling revealed that expression from P4 is dominant to the three upstream promoters, particularly upon exposure to chemical stressors that elicit DNA damage and disrupt cell wall stability; each of which have previously been shown to stimulate sigS expression. Importantly, expression of this fourth promoter, followed by at least one or more of the upstream promoters, is induced during growth in serum and upon phagocytosis by RAW 264.7 murine macrophage-like cells. Finally, we demonstrate that a downstream gene, SACOL1829, bears a large 3΄ UTR that spans the sigS-SACOL1828 coding region, and may serve to compete with the P4 transcript to inhibit σS production. Collectively, these findings reveal a unique operon architecture for the sigS locus that indicates the potential for novel regulatory mechanisms governing its expression.
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Affiliation(s)
- Halie K Miller
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave, Tampa, FL, 33620, USA
| | - Whittney N Burda
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave, Tampa, FL, 33620, USA
| | - Ronan K Carroll
- Department of Biological Sciences, Ohio University, Athens, OH, 45701, USA
| | - Lindsey N Shaw
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, 4202 E. Fowler Ave, Tampa, FL, 33620, USA
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Cossio-Ayala M, Domínguez-López M, Mendez-Enriquez E, Portillo-Téllez MDC, García-Hernández E. In vitro and in vivo antimicrobial activity of a synthetic peptide derived from the C-terminal region of human chemokine CCL13 against Pseudomonas aeruginosa. Peptides 2017; 94:49-55. [PMID: 28687455 DOI: 10.1016/j.peptides.2017.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/26/2017] [Accepted: 06/26/2017] [Indexed: 01/12/2023]
Abstract
Chemokines are important mediators of immunological responses during inflammation and under steady-state conditions. In addition to regulating cell migration, some chemotactic cytokines have direct effects on bacteria. Here, we characterized the antibacterial ability of the synthetic oligopeptide CCL1357-75, which corresponds to the carboxyl-terminal region of the human chemokine CCL13. In vitro measurements indicated that CCL1357-75 disrupts the cell membrane of Pseudomonas aeruginosa through a mechanism coupled to an unordered-helicoidal conformational transition. In a murine pneumonic model, CCL1357-75 improved mouse survival and bacterial clearance and decreased neutrophil recruitment, proinflammatory cytokines and lung pathology compared with that observed in untreated infected animals. Overall, our study supports the ability of chemokines and/or chemokine-derived oligopeptides to act as direct defense agents against pathogenic bacteria and suggests their potential use as alternative antibiotics.
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Affiliation(s)
- Mayte Cossio-Ayala
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04630, D.F., Mexico; Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04630, D.F., Mexico
| | - Mariana Domínguez-López
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04630, D.F., Mexico
| | - Erika Mendez-Enriquez
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04630, D.F., Mexico
| | | | - Enrique García-Hernández
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04630, D.F., Mexico.
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11
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Chen HY, Lin MH, Chen CC, Shu JC. The expression of fibronectin is significantly suppressed in macrophages to exert a protective effect against Staphylococcus aureus infection. BMC Microbiol 2017; 17:92. [PMID: 28407745 PMCID: PMC5390343 DOI: 10.1186/s12866-017-1003-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 04/07/2017] [Indexed: 11/20/2022] Open
Abstract
Background Fibronectin (Fn) plays a major role in the attachment of Staphylococcus aureus to host cells by bridging staphylococcal fibronectin-binding proteins (FnBPs) and cell-surface integrins. A previous study demonstrated that the phagocytosis of S. aureus by macrophages is enhanced in the presence of exogenous Fn. We recently found that FnBPs overexpression also enhances phagocytic activity. The effect of S. aureus infection on the expression of macrophage Fn was investigated. Result The level of Fn secreted by monocytes (THP-1), macrophages, human lung adenocarcinoma (A549) cells, and hepatocellular carcinoma (HepG2) cells in response to S. aureus infection was determined by Western blotting and it was significantly suppressed only in macrophages. The activation of signaling pathways associated with Fn regulation in macrophages and HepG2 cells was also investigated by Western blotting. Erk was activated in both macrophages and HepG2 cells, whereas Src-JNK-c-Jun signaling was only activated in macrophages. A significant decrease in macrophage viability was observed in response to S. aureus infection in the presence of exogenous Fn. Conclusion The Src-JNK-c-Jun signaling pathway was activated in macrophages in response to S. aureus infection and resulted in the suppression of Fn expression. This suppression may play a protective role in macrophages against S. aureus infection. This study provides the first demonstration that Fn is suppressed in macrophages by S. aureus infection. Electronic supplementary material The online version of this article (doi:10.1186/s12866-017-1003-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hong-Yi Chen
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, No. 259, Wenhua 1st Road, Guishan, Taoyuan, 333, Taiwan
| | - Mei-Hui Lin
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, No. 259, Wenhua 1st Road, Guishan, Taoyuan, 333, Taiwan.,Research Center for Pathogenic Bacteria, Chang Gung University, Taoyuan, Taiwan.,Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Chien-Cheng Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
| | - Jwu-Ching Shu
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, No. 259, Wenhua 1st Road, Guishan, Taoyuan, 333, Taiwan. .,Research Center for Pathogenic Bacteria, Chang Gung University, Taoyuan, Taiwan. .,Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
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12
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Di Gregorio S, Fernandez S, Cuirolo A, Verlaine O, Amoroso A, Mengin-Lecreulx D, Famiglietti A, Joris B, Mollerach M. Different Vancomycin-Intermediate Staphylococcus aureus Phenotypes Selected from the Same ST100-hVISA Parental Strain. Microb Drug Resist 2016; 23:44-50. [PMID: 27991847 PMCID: PMC5206683 DOI: 10.1089/mdr.2016.0160] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The aim of this study is to characterize the factors related to peptidoglycan metabolism in isogenic hVISA/VISA ST100 strains. Recently, we reported the increase in IS256 transposition in invasive hVISA ST100 clinical strains isolated from the same patient (D1 and D2) before and after vancomycin treatment and two laboratory VISA mutants (D23C9 and D2P11) selected from D2 in independent experiments. High performance liquid chromatography-mass spectrometry (HPLC-MS) analysis of peptidoglycan muropeptides showed increased proportion of monomeric muropeptides and a concomitant decrease in the proportion of tetrameric muropeptide in D2 and derived mutants when compared to the original strain D1. In addition, strain D2 and its derived mutants showed an increase in cell wall thickness with increased pbp2 gene expression. The VISA phenotype was not stable in D2P11 and showed a reduced autolysis profile. On the other hand, the mutant D23C9 differentiates from D2 and D2P11 in the autolysis profile, and pbp4 transcription profile. D2-derived mutants exhibited differences in the susceptibility to other antimicrobials. Our results highlight the possibility of selection of different VISA phenotypes from a single hVISA-ST100 genetic background.
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Affiliation(s)
- Sabrina Di Gregorio
- 1 Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología, Cátedra de Microbiología, Buenos Aires, Argentina
| | - Silvina Fernandez
- 1 Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología, Cátedra de Microbiología, Buenos Aires, Argentina
| | - Arabela Cuirolo
- 2 Unité de Physiologie et génétique bactériennes, Département de Sciences de la vie, Centre d'Ingénierie des Protéines, Université de Liège , Liège, Belgique
| | - Olivier Verlaine
- 2 Unité de Physiologie et génétique bactériennes, Département de Sciences de la vie, Centre d'Ingénierie des Protéines, Université de Liège , Liège, Belgique
| | - Ana Amoroso
- 2 Unité de Physiologie et génétique bactériennes, Département de Sciences de la vie, Centre d'Ingénierie des Protéines, Université de Liège , Liège, Belgique
| | - Dominique Mengin-Lecreulx
- 3 Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, France
| | - Angela Famiglietti
- 4 Universidad de Buenos Aires, Hospital de Clínicas José de San Martín, Laboratorio de Bacteriología Clínica, Buenos Aires, Argentina
| | - Bernard Joris
- 2 Unité de Physiologie et génétique bactériennes, Département de Sciences de la vie, Centre d'Ingénierie des Protéines, Université de Liège , Liège, Belgique
| | - Marta Mollerach
- 1 Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología, Cátedra de Microbiología, Buenos Aires, Argentina
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13
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Liu Q, Yeo WS, Bae T. The SaeRS Two-Component System of Staphylococcus aureus. Genes (Basel) 2016; 7:genes7100081. [PMID: 27706107 PMCID: PMC5083920 DOI: 10.3390/genes7100081] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/23/2016] [Indexed: 12/20/2022] Open
Abstract
In the Gram-positive pathogenic bacterium Staphylococcus aureus, the SaeRS twocomponent system (TCS) plays a major role in controlling the production of over 20 virulence factors including hemolysins, leukocidins, superantigens, surface proteins, and proteases. The SaeRS TCS is composed of the sensor histidine kinase SaeS, response regulator SaeR, and two auxiliary proteins SaeP and SaeQ. Since its discovery in 1994, the sae locus has been studied extensively, and its contributions to staphylococcal virulence and pathogenesis have been well documented and understood; however, the molecular mechanism by which the SaeRS TCS receives and processes cognate signals is not. In this article, therefore, we review the literature focusing on the signaling mechanism and its interaction with other global regulators.
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Affiliation(s)
- Qian Liu
- Department of Laboratory Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China.
| | - Won-Sik Yeo
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest, Gary, IN 46408, USA.
| | - Taeok Bae
- Department of Microbiology and Immunology, Indiana University School of Medicine-Northwest, Gary, IN 46408, USA.
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14
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Modulation of Staphylococcus aureus Biofilm Matrix by Subinhibitory Concentrations of Clindamycin. Antimicrob Agents Chemother 2016; 60:5957-67. [PMID: 27458233 DOI: 10.1128/aac.00463-16] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/13/2016] [Indexed: 12/31/2022] Open
Abstract
Staphylococcus aureus biofilms are extremely difficult to treat. They provide a protected niche for the bacteria, rendering them highly recalcitrant toward host defenses as well as antibiotic treatment. Bacteria within a biofilm are shielded from the immune system by the formation of an extracellular polymeric matrix, composed of polysaccharides, extracellular DNA (eDNA), and proteins. Many antibiotics do not readily penetrate biofilms, resulting in the presence of subinhibitory concentrations of antibiotics. Here, we show that subinhibitory concentrations of clindamycin triggered a transcriptional stress response in S. aureus via the alternative sigma factor B (σ(B)) and upregulated the expression of the major biofilm-associated genes atlA, lrgA, agrA, the psm genes, fnbA, and fnbB Our data suggest that subinhibitory concentrations of clindamycin alter the ability of S. aureus to form biofilms and shift the composition of the biofilm matrix toward higher eDNA content. An understanding of the molecular mechanisms underlying biofilm assembly and dispersal in response to subinhibitory concentrations of clinically relevant antibiotics such as clindamycin is critical to further optimize antibiotic treatment strategies of biofilm-associated S. aureus infections.
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15
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Resilience in the Face of Uncertainty: Sigma Factor B Fine-Tunes Gene Expression To Support Homeostasis in Gram-Positive Bacteria. Appl Environ Microbiol 2016; 82:4456-4469. [PMID: 27208112 DOI: 10.1128/aem.00714-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gram-positive bacteria are ubiquitous and diverse microorganisms that can survive and sometimes even thrive in continuously changing environments. The key to such resilience is the ability of members of a population to respond and adjust to dynamic conditions in the environment. In bacteria, such responses and adjustments are mediated, at least in part, through appropriate changes in the bacterial transcriptome in response to the conditions encountered. Resilience is important for bacterial survival in diverse, complex, and rapidly changing environments and requires coordinated networks that integrate individual, mechanistic responses to environmental cues to enable overall metabolic homeostasis. In many Gram-positive bacteria, a key transcriptional regulator of the response to changing environmental conditions is the alternative sigma factor σ(B) σ(B) has been characterized in a subset of Gram-positive bacteria, including the genera Bacillus, Listeria, and Staphylococcus Recent insight from next-generation-sequencing results indicates that σ(B)-dependent regulation of gene expression contributes to resilience, i.e., the coordination of complex networks responsive to environmental changes. This review explores contributions of σ(B) to resilience in Bacillus, Listeria, and Staphylococcus and illustrates recently described regulatory functions of σ(B).
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16
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RpiRc Is a Pleiotropic Effector of Virulence Determinant Synthesis and Attenuates Pathogenicity in Staphylococcus aureus. Infect Immun 2016; 84:2031-2041. [PMID: 27113358 DOI: 10.1128/iai.00285-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 04/17/2016] [Indexed: 12/16/2022] Open
Abstract
In Staphylococcus aureus, metabolism is intimately linked with virulence determinant biosynthesis, and several metabolite-responsive regulators have been reported to mediate this linkage. S. aureus possesses at least three members of the RpiR family of transcriptional regulators. Of the three RpiR homologs, RpiRc is a potential regulator of the pentose phosphate pathway, which also regulates RNAIII levels. RNAIII is the regulatory RNA of the agr quorum-sensing system that controls virulence determinant synthesis. The effect of RpiRc on RNAIII likely involves other regulators, as the regulators that bind the RNAIII promoter have been intensely studied. To determine which regulators might bridge the gap between RpiRc and RNAIII, sarA, sigB, mgrA, and acnA mutations were introduced into an rpiRc mutant background, and the effects on RNAIII were determined. Additionally, phenotypic and genotypic differences were examined in the single and double mutant strains, and the virulence of select strains was examined using two different murine infection models. The data suggest that RpiRc affects RNAIII transcription and the synthesis of virulence determinants in concert with σ(B), SarA, and the bacterial metabolic status to negatively affect virulence.
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17
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Rouha H, Badarau A, Visram ZC, Battles MB, Prinz B, Magyarics Z, Nagy G, Mirkina I, Stulik L, Zerbs M, Jägerhofer M, Maierhofer B, Teubenbacher A, Dolezilkova I, Gross K, Banerjee S, Zauner G, Malafa S, Zmajkovic J, Maier S, Mabry R, Krauland E, Wittrup KD, Gerngross TU, Nagy E. Five birds, one stone: neutralization of α-hemolysin and 4 bi-component leukocidins of Staphylococcus aureus with a single human monoclonal antibody. MAbs 2015; 7:243-54. [PMID: 25523282 PMCID: PMC5045134 DOI: 10.4161/19420862.2014.985132] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen associated with high mortality. The emergence of antibiotic resistance and the inability of antibiotics to counteract bacterial cytotoxins involved in the pathogenesis of S. aureus call for novel therapeutic approaches, such as passive immunization with monoclonal antibodies (mAbs). The complexity of staphylococcal pathogenesis and past failures with single mAb products represent considerable barriers for antibody-based therapeutics. Over the past few years, efforts have focused on neutralizing α-hemolysin. Recent findings suggest that the concerted actions of several cytotoxins, including the bi-component leukocidins play important roles in staphylococcal pathogenesis. Therefore, we aimed to isolate mAbs that bind to multiple cytolysins by employing high diversity human IgG1 libraries presented on the surface of yeast cells. Here we describe cross-reactive antibodies with picomolar affinity for α-hemolysin and 4 different bi-component leukocidins that share only ∼26% overall amino acid sequence identity. The molecular basis of cross-reactivity is the recognition of a conformational epitope shared by α-hemolysin and F-components of gamma-hemolysin (HlgAB and HlgCB), LukED and LukSF (Panton-Valentine Leukocidin). The amino acids predicted to form the epitope are conserved and known to be important for cytotoxic activity. We found that a single cross-reactive antibody prevented lysis of human phagocytes, epithelial and red blood cells induced by α-hemolysin and leukocidins in vitro, and therefore had superior effectiveness compared to α-hemolysin specific antibodies to protect from the combined cytolytic effect of secreted S. aureus toxins. Such mAb afforded high levels of protection in murine models of pneumonia and sepsis.
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Key Words
- BLI, biolayer interferometry
- EC50, effective concentration
- Hla, α-hemolysin
- HlgAB and HlgCB, gamma-hemolysins
- IC50, inhibitory concentration
- LukED, leukocidin ED
- LukSF, leukocidin SF
- PMN, polymorphonuclear cells
- RBC, red blood cell
- Staphylococcus aureus
- engineered cross-reactivity
- exotoxins
- in vitro potency
- in vivo efficacy
- mAb, monoclonal antibody
- monoclonal antibody
- toxin neutralization
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18
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High Glucose Concentration Promotes Vancomycin-Enhanced Biofilm Formation of Vancomycin-Non-Susceptible Staphylococcus aureus in Diabetic Mice. PLoS One 2015; 10:e0134852. [PMID: 26244880 PMCID: PMC4526670 DOI: 10.1371/journal.pone.0134852] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/14/2015] [Indexed: 12/14/2022] Open
Abstract
We previously demonstrated that vancomycin treatment increased acquisition of eDNA and enhanced biofilm formation of drug-resistant Staphylococcus aureus through a cidA-mediated autolysis mechanism. Recently we found that such enhancement became more significant under a higher glucose concentration in vitro. We propose that besides improper antibiotic treatment, increased glucose concentration environment in diabetic animals may further enhance biofilm formation of drug-resistant S. aureus. To address this question, the diabetic mouse model infected by vancomycin-resistant S. aureus (VRSA) was used under vancomycin treatment. The capacity to form biofilms was evaluated through a catheter-associated biofilm assay. A 10- and 1000-fold increase in biofilm-bound bacterial colony forming units was observed in samples from diabetic mice without and with vancomycin treatment, respectively, compared to healthy mice. By contrast, in the absence of glucose vancomycin reduced propensity to form biofilms in vitro through the increased production of proteases and DNases from VRSA. Our study highlights the potentially important role of increased glucose concentration in enhancing biofilm formation in vancomycin-treated diabetic mice infected by drug-resistant S. aureus.
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19
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Arya R, Ravikumar R, Santhosh RS, Princy SA. SarA based novel therapeutic candidate against Staphylococcus aureus associated with vascular graft infections. Front Microbiol 2015; 6:416. [PMID: 26074884 PMCID: PMC4447123 DOI: 10.3389/fmicb.2015.00416] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 04/20/2015] [Indexed: 12/03/2022] Open
Abstract
Staphylococcus aureus is a common pathogen seen in prosthetic vascular graft, leading to high morbidity and mortality. The virulence genes for severity of infections are under the control of global regulators. Staphylococcal accessory regulator A (SarA) a known master controller of biofilm formation is an attractive target for the drug development. A structure based screening of lead compounds was employed for the identification of novel small molecule inhibitors targeted to interact to the DNA binding domain of the transcriptional activator, SarA and hinder its response over the control of genes that up-regulate the phenotype, biofilm. The top-hit SarA selective inhibitor, 4-[(2,4-diflurobenzyl)amino] cyclohexanol (SarABI) was further validated in-vitro for its efficacy. The SarABI was found to have MBIC50value of 200 μg/ml and also down-regulated the expression of the RNA effector, (RNAIII), Hemolysin (hld), and fibronectin-binding protein (fnbA). The anti-adherence property of SarABI on S. aureus invasion to the host epithelial cell lines (Hep-2) was examined where no significant attachment of S. aureus was observed. The SarABI inhibits the colonization of MDR S. aureus in animal model experiment significantly cohere to the molecular docking studies and in vitro experiments. So, we propose that the SarABI could be a novel substitute to overcome a higher degree of MDR S. aureus colonization on vascular graft.
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Affiliation(s)
- Rekha Arya
- Quorum Sensing Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University Thanjavur, India
| | - R Ravikumar
- Department of Chemistry, SASTRA University Thanjavur, India
| | - R S Santhosh
- Genetic Engineering Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University Thanjavur, India
| | - S Adline Princy
- Quorum Sensing Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University Thanjavur, India
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20
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Cázares-Domínguez V, Ochoa SA, Cruz-Córdova A, Rodea GE, Escalona G, Olivares AL, Olivares-Trejo JDJ, Velázquez-Guadarrama N, Xicohtencatl-Cortes J. Vancomycin modifies the expression of the agr system in multidrug-resistant Staphylococcus aureus clinical isolates. Front Microbiol 2015; 6:369. [PMID: 25999924 PMCID: PMC4419724 DOI: 10.3389/fmicb.2015.00369] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/11/2015] [Indexed: 01/08/2023] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen that colonizes human hosts and causes a wide variety of diseases. Two interacting regulatory systems called agr (accessory gene regulator) and sar (staphylococcal accessory regulator) are involved in the regulation of virulence factors. The aim of this study was to evaluate the effect of vancomycin on hld and spa gene expression during the exponential and post-exponential growth phases in multidrug-resistant (MDR) S. aureus. Methods: Antibiotic susceptibility was evaluated by the standard microdilution method. The phylogenetic profile was obtained by pulsed-field gel electrophoresis (PFGE). Polymorphisms of agr and SCCmec (staphylococcal cassette chromosome mec) were analyzed by multiplex polymerase chain reaction (PCR). The expression levels of hld and spa were analyzed by reverse transcription-PCR. An enzyme-linked immunosorbent assay (ELISA) was performed to detect protein A, and biofilm formation was analyzed via crystal violet staining. Results: In total, 60.60% (20/33) of S. aureus clinical isolates were MDR. Half (10/20) of the MDR S. aureus isolates were distributed in subcluster 10, with >90% similarity among them. In the isolates of this subcluster, a high prevalence (100%) for the agrII and the cassette SCCmec II polymorphisms was found. Our data showed significant increases in hld expression during the post-exponential phase in the presence and absence of vancomycin. Significant increases in spa expression, protein A production and biofilm formation were observed during the post-exponential phase when the MDR S. aureus isolates were challenged with vancomycin. Conclusion: The polymorphism agrII, which is associated with nosocomial isolates, was the most prevalent polymorphism in MDR S. aureus. Additionally, under our study conditions, vancomycin modified hld and spa expression in these clinical isolates. Therefore, vancomycin may regulate alternative systems that jointly participate in the regulation of these virulence factors.
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Affiliation(s)
- Vicenta Cázares-Domínguez
- Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez México DF, Mexico
| | - Sara A Ochoa
- Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez México DF, Mexico
| | - Ariadnna Cruz-Córdova
- Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez México DF, Mexico
| | - Gerardo E Rodea
- Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez México DF, Mexico
| | - Gerardo Escalona
- Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez México DF, Mexico
| | - Alma L Olivares
- Laboratorio de Infectología, Hospital Infantil de México Federico Gómez México DF, Mexico
| | | | | | - Juan Xicohtencatl-Cortes
- Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez México DF, Mexico
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21
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Tuchscherr L, Bischoff M, Lattar SM, Noto Llana M, Pförtner H, Niemann S, Geraci J, Van de Vyver H, Fraunholz MJ, Cheung AL, Herrmann M, Völker U, Sordelli DO, Peters G, Löffler B. Sigma Factor SigB Is Crucial to Mediate Staphylococcus aureus Adaptation during Chronic Infections. PLoS Pathog 2015; 11:e1004870. [PMID: 25923704 PMCID: PMC4414502 DOI: 10.1371/journal.ppat.1004870] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/09/2015] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen that causes a range of infections from acute invasive to chronic and difficult-to-treat. Infection strategies associated with persisting S. aureus infections are bacterial host cell invasion and the bacterial ability to dynamically change phenotypes from the aggressive wild-type to small colony variants (SCVs), which are adapted for intracellular long-term persistence. The underlying mechanisms of the bacterial switching and adaptation mechanisms appear to be very dynamic, but are largely unknown. Here, we analyzed the role and the crosstalk of the global S. aureus regulators agr, sarA and SigB by generating single, double and triple mutants, and testing them with proteome analysis and in different in vitro and in vivo infection models. We were able to demonstrate that SigB is the crucial factor for adaptation in chronic infections. During acute infection, the bacteria require the simultaneous action of the agr and sarA loci to defend against invading immune cells by causing inflammation and cytotoxicity and to escape from phagosomes in their host cells that enable them to settle an infection at high bacterial density. To persist intracellularly the bacteria subsequently need to silence agr and sarA. Indeed agr and sarA deletion mutants expressed a much lower number of virulence factors and could persist at high numbers intracellularly. SigB plays a crucial function to promote bacterial intracellular persistence. In fact, ΔsigB-mutants did not generate SCVs and were completely cleared by the host cells within a few days. In this study we identified SigB as an essential factor that enables the bacteria to switch from the highly aggressive phenotype that settles an acute infection to a silent SCV-phenotype that allows for long-term intracellular persistence. Consequently, the SigB-operon represents a possible target to develop preventive and therapeutic strategies against chronic and therapy-refractory infections.
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Affiliation(s)
- Lorena Tuchscherr
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene, University of Saarland Medical Center, Homburg, Germany
| | - Santiago M. Lattar
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Mariangeles Noto Llana
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Henrike Pförtner
- Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Silke Niemann
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Jennifer Geraci
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Hélène Van de Vyver
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Martin J. Fraunholz
- Department of Microbiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Ambrose L. Cheung
- Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Mathias Herrmann
- Institute of Medical Microbiology and Hygiene, University of Saarland Medical Center, Homburg, Germany
| | - Uwe Völker
- Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Daniel O. Sordelli
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Bettina Löffler
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
- * E-mail:
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22
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Müller M, Reiß S, Schlüter R, Mäder U, Beyer A, Reiß W, Marles-Wright J, Lewis RJ, Pförtner H, Völker U, Riedel K, Hecker M, Engelmann S, Pané-Farré J. Deletion of membrane-associated Asp23 leads to upregulation of cell wall stress genes in Staphylococcus aureus. Mol Microbiol 2014; 93:1259-68. [PMID: 25074408 DOI: 10.1111/mmi.12733] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2014] [Indexed: 12/01/2022]
Abstract
With about 25 000 molecules per cell, Asp23 is one of the most abundant proteins in Staphylococcus aureus. Asp23 has been characterized as a protein that, following an alkaline shock, accumulates in the soluble protein fraction. Transcription of the asp23 gene is exclusively regulated by the alternative sigma factor σ(B) , which controls the response of the bacterium to environmental stress. Sequence analysis identified Asp23 as a member of the widely distributed Pfam DUF322 family, precluding functional predictions based on its sequence. Using fluorescence microscopy we found that Asp23 colocalized with the cell membrane of Staphylococcus aureus. Since Asp23 has no recognizable transmembrane spanning domains, we initiated a search for proteins that link Asp23 to the cell membrane. We identified SAOUHSC_02443 as the Asp23 membrane anchor and have renamed it AmaP (Asp23 membrane anchoring protein). Deletion of the asp23 gene led to an upregulation of the cell wall stress response. In summary, we have identified Asp23 as a membrane-associated protein and we suggest a function for Asp23 in cell envelope homoeostasis.
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Affiliation(s)
- Marret Müller
- Institute for Microbiology, Ernst-Moritz-Arndt-University, Friedrich-Ludwig-Jahn-Straße 15, D-17489, Greifswald, Germany
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Knockout of extracytoplasmic function sigma factor ECF-10 affects stress resistance and biofilm formation in Pseudomonas putida KT2440. Appl Environ Microbiol 2014; 80:4911-9. [PMID: 24907323 DOI: 10.1128/aem.01291-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas putida is a Gram-negative soil bacterium which is well-known for its versatile lifestyle, controlled by a large repertoire of transcriptional regulators. Besides one- and two-component regulatory systems, the genome of P. putida reveals 19 extracytoplasmic function (ECF) sigma factors involved in the adaptation to changing environmental conditions. In this study, we demonstrate that knockout of extracytoplasmic function sigma factor ECF-10, encoded by open reading frame PP4553, resulted in 2- to 4-fold increased antibiotic resistance to quinolone, β-lactam, sulfonamide, and chloramphenicol antibiotics. In addition, the ECF-10 mutant exhibited enhanced formation of biofilms after 24 h of incubation. Transcriptome analysis using Illumina sequencing technology resulted in the detection of 12 genes differentially expressed (>2-fold) in the ECF-10 knockout mutant strain compared to their levels of expression in wild-type cells. Among the upregulated genes were ttgA, ttgB, and ttgC, which code for the major multidrug efflux pump TtgABC in P. putida KT2440. Investigation of an ECF-10 and ttgA double-knockout strain and a ttgABC-overexpressing strain demonstrated the involvement of efflux pump TtgABC in the stress resistance and biofilm formation phenotypes of the ECF-10 mutant strain, indicating a new role for this efflux pump beyond simple antibiotic resistance in P. putida KT2440.
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Pförtner H, Burian MS, Michalik S, Depke M, Hildebrandt P, Dhople VM, Pané-Farré J, Hecker M, Schmidt F, Völker U. Activation of the alternative sigma factor SigB of Staphylococcus aureus following internalization by epithelial cells – An in vivo proteomics perspective. Int J Med Microbiol 2014; 304:177-87. [DOI: 10.1016/j.ijmm.2013.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Herrmann M. Antimicrobial Effects Promoting Biofilm Formation and Persistent Disease: The Role of a DNA-Binding Regulator, SarA, in Staphylococcal Endocarditis. J Infect Dis 2014; 209:1153-5. [DOI: 10.1093/infdis/jiu008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Hessling B, Bonn F, Otto A, Herbst FA, Rappen GM, Bernhardt J, Hecker M, Becher D. Global proteome analysis of vancomycin stress in Staphylococcus aureus. Int J Med Microbiol 2013; 303:624-34. [DOI: 10.1016/j.ijmm.2013.08.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 08/19/2013] [Accepted: 08/25/2013] [Indexed: 11/28/2022] Open
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Hsieh YT, Lin MH, Ho HY, Chen LC, Chen CC, Shu JC. Glucose-6-phosphate dehydrogenase (G6PD)-deficient epithelial cells are less tolerant to infection by Staphylococcus aureus. PLoS One 2013; 8:e79566. [PMID: 24223971 PMCID: PMC3817128 DOI: 10.1371/journal.pone.0079566] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 09/25/2013] [Indexed: 01/12/2023] Open
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway and provides reducing energy to all cells by maintaining redox balance. The most common clinical manifestations in patients with G6PD deficiency are neonatal jaundice and acute hemolytic anemia. The effects of microbial infection in patients with G6PD deficiency primarily relate to the hemolytic anemia caused by Plasmodium or viral infections and the subsequent medication that is required. We are interested in studying the impact of bacterial infection in G6PD-deficient cells. G6PD knock down A549 lung carcinoma cells, together with the common pathogen Staphylococcus aureus, were employed in our cell infection model. Here, we demonstrate that a lower cell viability was observed among G6PD-deficient cells when compared to scramble controls upon bacterial infection using the MTT assay. A significant increase in the intracellular ROS was detected among S. aureus-infected G6PD-deficient cells by observing dichlorofluorescein (DCF) intensity within cells under a fluorescence microscope and quantifying this signal using flow cytometry. The impairment of ROS removal is predicted to enhance apoptotic activity in G6PD-deficient cells, and this enhanced apoptosis was observed by annexin V/PI staining under a confocal fluorescence microscope and quantified by flow cytometry. A higher expression level of the intrinsic apoptotic initiator caspase-9, as well as the downstream effector caspase-3, was detected by Western blotting analysis of G6PD-deficient cells following bacterial infection. In conclusion, we propose that bacterial infection, perhaps the secreted S. aureus α-hemolysin in this case, promotes the accumulation of intracellular ROS in G6PD-deficient cells. This would trigger a stronger apoptotic activity through the intrinsic pathway thereby reducing cell viability when compared to wild type cells.
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Affiliation(s)
- Yi-Ting Hsieh
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Mei-Hui Lin
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Research Center for Pathogenic Bacteria, Chang Gung University, Taoyuan, Taiwan
| | - Hung-Yao Ho
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Lei-Chin Chen
- Department of Nutrition, I-Shou University, Kaohsiung, Taiwan
| | - Chien-Cheng Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
- * E-mail: (C-CC); (J-CS)
| | - Jwu-Ching Shu
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Research Center for Pathogenic Bacteria, Chang Gung University, Taoyuan, Taiwan
- * E-mail: (C-CC); (J-CS)
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Dangel A, Ackermann N, Abdel-Hadi O, Maier R, Önder K, Francois P, Müller CW, Pané-Farré J, Engelmann S, Schrenzel J, Heesemann J, Lindermayr C. A de novo-designed antimicrobial peptide with activity against multiresistant Staphylococcus aureus acting on RsbW kinase. FASEB J 2013; 27:4476-88. [PMID: 23901070 DOI: 10.1096/fj.13-234575] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Antimicrobial peptides are a promising complement to common antibiotics, development of resistance to which is a growing problem. Here we present a de novo-designed peptide, SP1-1 (RKKRLKLLKRLL-NH2), with antimicrobial activity against multiresistant Staphylococcus aureus (minimal inhibitory concentration: 6.25 μM). Elucidation of the mode of action of this peptide revealed a strong interaction with RsbW kinase (Kd: 6.01±2.73 nM), a serine kinase negatively regulating the activity of the transcription factor σB (SigB). SP1-1 binding and functional modulation of RsbW were shown in vitro by a combination of biochemical, molecular, and biophysical methods, which were further genetically evidenced in vivo by analysis of S. aureus ΔsigB deletion mutants. Intracellular localization of the peptide was demonstrated using nanometer-scaled secondary ion mass spectrometry. Moreover, microarray analysis revealed that transcription of numerous genes, involved in cell wall and amino acid metabolism, transport mechanisms, virulence, and pigmentation, is affected. Interestingly, several WalR binding motif containing genes are induced by SP1-1. In sum, the designed peptide SP1-1 seems to have multiple modes of action, including inhibition of a kinase, and therefore might contribute to the development of new antibacterial compounds, giving bacterial kinase inhibition a closer inspection.
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Affiliation(s)
- Alexandra Dangel
- 1Helmholtz Zentrum Munich, Landstrasse, München-Neuherberg, D-85764 Germany.
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Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 602] [Impact Index Per Article: 54.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
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Junecko JM, Zielinska AK, Mrak LN, Ryan DC, Graham JW, Smeltzer MS, Lee CY. Transcribing virulence in Staphylococcus aureus. World J Clin Infect Dis 2012; 2:63-76. [DOI: 10.5495/wjcid.v2.i4.63] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is an important human pathogen capable of causing a diverse range of infections. Once regarded as an opportunistic pathogen causing primarily nosocomial infections, recent years have seen the emergence of S. aureus strains capable of causing serious infection even in otherwise healthy human hosts. There has been much debate about whether this transition is a function of unique genotypic characteristics or differences in the expression of conserved virulence factors, but irrespective of this debate it is clear that the ability of S. aureus to cause infection in all of its diverse forms is heavily influenced by its ability to modulate gene expression in response to changing conditions within the human host. Indeed, the S. aureus genome encodes more than 100 transcriptional regulators that modulate the production of virulence factors either directly via interactions with cis elements associated with genes encoding virulence factors or indirectly through their complex interactions with each other. The goal of this review is to summarize recent work describing these regulators and their contribution to defining S. aureus as a human pathogen.
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Zhou Q, Wang L, Yin X, Feng X, Shang J, Luo Q. SigB-Dependent Tolerance to Protein Synthesis-Inhibiting Antibiotics in Listeria monocytogenes EGDe. Curr Microbiol 2011; 64:234-41. [DOI: 10.1007/s00284-011-0058-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 11/16/2011] [Indexed: 10/14/2022]
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The Listeria monocytogenes σB regulon and its virulence-associated functions are inhibited by a small molecule. mBio 2011; 2:mBio.00241-11. [PMID: 22128349 PMCID: PMC3225968 DOI: 10.1128/mbio.00241-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The stress-responsive alternative sigma factor σB is conserved across diverse Gram-positive bacterial genera. In Listeria monocytogenes, σB regulates transcription of >150 genes, including genes contributing to virulence and to bacterial survival under host-associated stress conditions, such as those encountered in the human gastrointestinal lumen. An inhibitor of L. monocytogenes σB activity was identified by screening ~57,000 natural and synthesized small molecules using a high-throughput cell-based assay. The compound fluoro-phenyl-styrene-sulfonamide (FPSS) (IC50 = 3.5 µM) downregulated the majority of genes previously identified as members of the σB regulon in L. monocytogenes 10403S, thus generating a transcriptional profile comparable to that of a 10403S ΔsigB strain. Specifically, of the 208 genes downregulated by FPSS, 75% had been identified previously as positively regulated by σB. Downregulated genes included key virulence and stress response genes, such as inlA, inlB, bsh, hfq, opuC, and bilE. From a functional perspective, FPSS also inhibited L. monocytogenes invasion of human intestinal epithelial cells and bile salt hydrolase activity. The ability of FPSS to inhibit σB activity in both L. monocytogenes and Bacillus subtilis indicates its utility as a specific inhibitor of σB across multiple Gram-positive genera. The σB transcription factor regulates expression of genes responsible for bacterial survival under changing environmental conditions and for virulence; therefore, this alternative sigma factor is important for transmission of L. monocytogenes and other Gram-positive bacteria. Regulation of σB activity is complex and tightly controlled, reflecting the key role of this factor in bacterial metabolism. We present multiple lines of evidence indicating that fluoro-phenyl-styrene-sulfonamide (FPSS) specifically inhibits activity of σB across Gram-positive bacterial genera, i.e., in both Listeria monocytogenes and Bacillus subtilis. Therefore, FPSS is an important new tool that will enable novel approaches for exploring complex regulatory networks in L. monocytogenes and other Gram-positive pathogens and for investigating small-molecule applications for controlling pathogen transmission.
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