1
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Rathi R. Potential inhibitors of FemC to combat Staphylococcus aureus: virtual screening, molecular docking, dynamics simulation, and MM-PBSA analysis. J Biomol Struct Dyn 2023; 41:10495-10506. [PMID: 36524526 DOI: 10.1080/07391102.2022.2157328] [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: 09/15/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022]
Abstract
FemC is a methicillin resistance factor involved in the alterations of peptidoglycan and glutamine synthesis in Staphylococcus aureus. To identify the potent antibacterial agents, antibacterial molecules were screened against the predicted and validated FemC model. Based on docking scores, presence of essential interactions with active site residues of FemC, pharmacokinetic, and ADMET properties, six candidates were shortlisted and subjected to molecular dynamics to evaluate the stability of FemC-ligand complexes. Further, per residue decomposition analysis and Molecular Mechanics/Poisson-Boltzmann Surface Area (MMPBSA) analysis confirmed that S15, M16, S17, R31, R43, Q47, K48 and R49 of FemC played a vital role in the formation of lower energy stable FemC-inhibitor(s) complexes. Therefore, in the present study, the reported six molecules (Z317461228, Z92241701, Z30923155, Z30202349, Z2609517102 and Z92470167) may pave the path to design the scaffold of novel potent antimicrobials against S. aureus.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Ravi Rathi
- Amity School of Applied Sciences, Amity University Haryana, Gurgaon, Haryana, India
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2
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Rathi R, Kumari R, Pathak SR, Dalal V. Promising antibacterials for LLM of Staphylococcus aureus using virtual screening, molecular docking, dynamics, and MMPBSA. J Biomol Struct Dyn 2023; 41:7277-7289. [PMID: 36073371 DOI: 10.1080/07391102.2022.2119278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/25/2022] [Indexed: 10/14/2022]
Abstract
In S. aureus, lipophilic membrane (LLM) protein is a methicillin resistance factor and is an essential role in peptidoglycan metabolism. The virtual screening of antibacterial molecules against the model of LLM was performed to identify the potent antibacterial molecules. Molecular docking results of pharmacokinetic filtered molecules illustrated that five molecules had higher binding affinities than tunicamycin (TUM) and were stabled via non-covalent interactions (hydrogen bond and hydrophobic interactions) at the active site of LLM. Further, molecular dynamics results revealed that binding of identified antibacterial molecules with LLM resulted in stable LLM-inhibitor(s) complexes. Molecular Mechanics/Position-Boltzmann Surface Area (MMPBSA) analysis showed that LLM-inhibitor(s) complexes had high binding affinities in the range of -213.49 ± 2.24 to -227.42 ± 3.05 kJ/mol. The amino acid residues decomposition analysis confirmed that identified antibacterial molecules bound at the active site (Asn148, Leu149, Asp151, Asp208, His269, His271, and His272) of LLM. Noticeably, the current study found five antibacterial molecules (BDE 27575101, BDE 33638168, BDE 33672484, LAS 51502073, and BDE 25098678) were highly potent than TUM and even than earlier reported molecules. Therefore, here reported antibacterial molecules may be used directly or developed to inhibit LLM of S. aureus.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Ravi Rathi
- Amity School of Applied Sciences, Amity University Haryana, Haryana, India
| | - Reena Kumari
- Department of Mathematics and Statistics, Swami Vivekanand Subharti University, Meerut, India
| | - Seema R Pathak
- Amity School of Applied Sciences, Amity University Haryana, Haryana, India
| | - Vikram Dalal
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, USA
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3
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Ersoy SC, Gonçalves B, Cavaco G, Manna AC, Sobral RG, Nast CC, Proctor RA, Chambers HF, Cheung A, Bayer AS. Influence of Sodium Bicarbonate on Wall Teichoic Acid Synthesis and β-Lactam Sensitization in NaHCO 3-Responsive and Nonresponsive Methicillin-Resistant Staphylococcus aureus. Microbiol Spectr 2022; 10:e0342222. [PMID: 36377886 PMCID: PMC9769754 DOI: 10.1128/spectrum.03422-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 10/13/2022] [Indexed: 11/16/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) strains pose major treatment challenges due to their innate resistance to most β-lactams under standard in vitro antimicrobial susceptibility testing conditions. A novel phenotype among MRSA, termed "NaHCO3 responsiveness," where certain strains display increased susceptibility to β-lactams in the presence of NaHCO3, has been identified among a relatively large proportion of MRSA isolates. One underlying mechanism of NaHCO3 responsiveness appears to be related to decreased expression and altered functionality of several genes and proteins involved in cell wall synthesis and maturation. Here, we studied the impact of NaHCO3 on wall teichoic acid (WTA) synthesis, a process intimately linked to peptidoglycan (PG) synthesis and functionality, in NaHCO3-responsive versus -nonresponsive MRSA isolates. NaHCO3 sensitized responsive MRSA strains to cefuroxime, a specific penicillin-binding protein 2 (PBP2)-inhibitory β-lactam known to synergize with early WTA synthesis inhibitors (e.g., ticlopidine). Combining cefuroxime with ticlopidine with or without NaHCO3 suggested that these latter two agents target the same step in WTA synthesis. Further, NaHCO3 decreased the abundance and molecular weight of WTA only in responsive strains. Additionally, NaHCO3 stimulated increased autolysis and aberrant cell division in responsive strains, two phenotypes associated with disruption of WTA synthesis. Of note, studies of key genes involved in the WTA biosynthetic pathway (e.g., tarO, tarG, dltA, and fmtA) indicated that the inhibitory impact of NaHCO3 on WTA biosynthesis in responsive strains likely occurred posttranslationally. IMPORTANCE MRSA is generally viewed as resistant to standard β-lactam antibiotics. However, a NaHCO3-responsive phenotype is observed in a substantial proportion of clinical MRSA strains in vitro, i.e., isolates which demonstrate enhanced susceptibility to standard β-lactam antibiotics (e.g., oxacillin) in the presence of NaHCO3. This phenotype correlates with increased MRSA clearance in vivo by standard β-lactam antibiotics, suggesting that patients with infections caused by such MRSA strains might be amenable to treatment with β-lactams. The mechanism(s) behind this phenotype is not fully understood but appears to involve mecA-PBP2a production and maturation axes. Our study adds significantly to this body of knowledge in terms of additional mechanistic targets of NaHCO3 in selected MRSA strains. This investigation demonstrates that NaHCO3 has direct impacts on S. aureus wall teichoic acid biosynthesis in NaHCO3-responsive MRSA. These findings provide an additional target for new agents being designed to synergistically kill MRSA using β-lactam antibiotics.
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Affiliation(s)
| | - Barbara Gonçalves
- Laboratory of Molecular Microbiology of Bacterial Pathogens, UCIBIO, Applied Molecular Biosciences Unit, Department of Life Sciences, Nova School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Nova School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
| | - Gonçalo Cavaco
- Laboratory of Molecular Microbiology of Bacterial Pathogens, UCIBIO, Applied Molecular Biosciences Unit, Department of Life Sciences, Nova School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Nova School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
| | - Adhar C. Manna
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Rita G. Sobral
- Laboratory of Molecular Microbiology of Bacterial Pathogens, UCIBIO, Applied Molecular Biosciences Unit, Department of Life Sciences, Nova School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Nova School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
| | - Cynthia C. Nast
- Cedars-Sinai Medical Center, Los Angeles, California, USA
- Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Richard A. Proctor
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
- Department of Medical Microbiology/Immunology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | | | - Ambrose Cheung
- Department of Microbiology & Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Arnold S. Bayer
- The Lundquist Institute, Torrance, California, USA
- Geffen School of Medicine at UCLA, Los Angeles, California, USA
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4
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Kumari R, Dalal V. Identification of potential inhibitors for LLM of Staphylococcus aureus: structure-based pharmacophore modeling, molecular dynamics, and binding free energy studies. J Biomol Struct Dyn 2022; 40:9833-9847. [PMID: 34096457 DOI: 10.1080/07391102.2021.1936179] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Staphylococcus aureus causes various life-threatening diseases in humans and developed resistance to several antibiotics. Lipophilic membrane (LLM) protein regulates bacterial lysis rate and methicillin resistance level in S. aureus. To identify potential lead molecules, we performed a structure-based pharmacophore modeling by consideration of pharmacophore properties from LLM-tunicamycin complex. Further, virtual screening of ZINC database against the LLM was conducted and compounds were assessed for Lipinski and ADMET properties. Based on pharmacokinetic, and molecular docking, five potential inhibitors (ZINC000072380005, ZINC000257219974, ZINC000176045471, ZINC000035296288, and ZINC000008789934) were identified. Molecular dynamics simulation (MDS) of these five molecules was performed to evaluate the dynamics and stability of protein after binding of the ligands. Several MDS analysis like RMSD, RMSF, Rg, SASA, and PCA confirm that identified compounds exhibit higher binding affinity as compared to tunicamycin for LLM. The binding free energy analysis reveals that five compounds exhibit higher binding energy in the range of -218.76 to -159.52 kJ/mol, which is higher as compared to tunicamycin (-116.13 kJ/mol). Individual residue decomposition analysis concludes that Asn148, Asp151, Asp208, His271, and His272 of LLM play a significant role in the formation of lower energy LLM-inhibitor(s) complexes. These predicted molecules displayed pharmacological and structural properties and may be further used to develop novel antimicrobial compounds against S. aureus.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Reena Kumari
- Department of Mathematics and Statistics, Swami Vivekanand Subharti University, Meerut, India
| | - Vikram Dalal
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, USA
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5
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Dalal V, Kumari R. Screening and Identification of Natural Product‐Like Compounds as Potential Antibacterial Agents Targeting FemC of
Staphylococcus aureus
: An in‐Silico Approach. ChemistrySelect 2022. [DOI: 10.1002/slct.202201728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Vikram Dalal
- Department of Anesthesiology Washington University in St. Louis Missouri 63110 USA
| | - Reena Kumari
- Department of Mathematics and Statistics Swami Vivekanand Subharti University Meerut 250005 India
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6
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Ong ZX, Kannan B, Becker DL. Exploiting transposons in the study of Staphylococcus aureus pathogenesis and virulence. Crit Rev Microbiol 2022; 49:297-317. [PMID: 35438613 DOI: 10.1080/1040841x.2022.2052794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The opportunistic pathogen Staphylococcus aureus has an extremely complex relationship with humans. While the bacteria can exist as a commensal in many, it can cause a wide range of diseases and infections when turned pathogenic. Its presence is a determinant of chronicity and poor prognosis in numerous diseases, and its genomic plasticity causes S. aureus antimicrobial resistance to be one of the most dire contemporary medical problems to solve. Genetic manipulation of S. aureus has led to numerous findings that are vital in the fight against its pathogenesis. The utilisation of transposon mutant libraries for the systematic inspection of the S. aureus genome led to many landmark discoveries pertaining to the bacteria's pathogenicity, antimicrobial resistance acquisition, and virulence regulation. In this review, we describe mutant libraries, and their significant contributions, from various S. aureus strains created with commonly used transposons. The general workflow for the construction of libraries will be presented, along with a discussion of the challenges of undertaking the task of large-scale library construction. As the accessibility of transposon mutant library construction, screening, and analysis increases, this genetic tool could be further exploited in the study of the S. aureus genome.
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Affiliation(s)
- Zi Xin Ong
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Skin Research Institute, Singapore.,Nanyang Institute of Technology in Health and Medicine, Interdisciplinary Graduate Programme, Nanyang Technological University, Singapore
| | - Bavani Kannan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Skin Research Institute, Singapore
| | - David L Becker
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Skin Research Institute, Singapore
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7
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An Interplay of Multiple Positive and Negative Factors Governs Methicillin Resistance in Staphylococcus aureus. Microbiol Mol Biol Rev 2022; 86:e0015921. [PMID: 35420454 PMCID: PMC9199415 DOI: 10.1128/mmbr.00159-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of resistance to β-lactam antibiotics has made Staphylococcus aureus a clinical burden on a global scale. MRSA (methicillin-resistant S. aureus) is commonly known as a superbug. The ability of MRSA to proliferate in the presence of β-lactams is attributed to the acquisition of mecA, which encodes the alternative penicillin binding protein, PBP2A, which is insensitive to the antibiotics. Most MRSA isolates exhibit low-level β-lactam resistance, whereby additional genetic adjustments are required to develop high-level resistance. Although several genetic factors that potentiate or are required for high-level resistance have been identified, how these interact at the mechanistic level has remained elusive. Here, we discuss the development of resistance and assess the role of the associated components in tailoring physiology to accommodate incoming mecA.
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8
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Matsumoto Y, Ishii M, Hasegawa S, Sekimizu K. Enterococcus faecalis YM0831 suppresses sucrose-induced hyperglycemia in a silkworm model and in humans. Commun Biol 2019; 2:157. [PMID: 31069266 PMCID: PMC6497652 DOI: 10.1038/s42003-019-0407-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 03/25/2019] [Indexed: 12/12/2022] Open
Abstract
Hyperglycemia caused by excessive intake of sucrose leads to lifestyle-related diseases such as diabetes. Administration of a lactic acid bacterial strain to mice suppresses sucrose-induced hyperglycemia, but evidence for a similar effect in humans is lacking. Here we show that Enterococcus faecalis YM0831, identified using an in vivo screening system with silkworms, suppressed sucrose-induced hyperglycemia in humans. E. faecalis YM0831 also suppressed glucose-induced hyperglycemia in silkworms. E. faecalis YM0831 inhibited glucose uptake by the human intestinal epithelial cell line Caco-2. A transposon insertion mutant of E. faecalis YM0831, which showed decreased inhibitory activity against glucose uptake by Caco-2 cells, also exhibited decreased inhibitory activity against both sucrose-induced and glucose-induced hyperglycemia in silkworms. In human clinical trials, oral ingestion of E. faecalis YM0831 suppressed the increase in blood glucose in a sucrose tolerance test. These findings suggest that E. faecalis YM0831 inhibits intestinal glucose transport and suppresses sucrose-induced hyperglycemia in humans.
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Affiliation(s)
- Yasuhiko Matsumoto
- Teikyo University Institute of Medical Mycology, 359 Otsuka, Hachioji, Tokyo, 192-0395 Japan
- Department of Microbiology, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588 Japan
| | - Masaki Ishii
- Molecular Cell Biology Laboratory, Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi Nishitokyo-shi, Tokyo, 202-8585 Japan
- Genome Pharmaceuticals Institute Co. Ltd., 3-4-5-2D Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Setsuo Hasegawa
- Pharmaspur Inc., Toyo building, 1-2-10 Nihonbashi, Chuo-ku, Tokyo, 103-0027 Japan
| | - Kazuhisa Sekimizu
- Teikyo University Institute of Medical Mycology, 359 Otsuka, Hachioji, Tokyo, 192-0395 Japan
- Genome Pharmaceuticals Institute Co. Ltd., 3-4-5-2D Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
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9
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Quantitation of wall teichoic acid in Staphylococcus aureus by direct measurement of monomeric units using LC-MS/MS. Anal Biochem 2017; 518:9-15. [DOI: 10.1016/j.ab.2016.10.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/19/2016] [Accepted: 10/30/2016] [Indexed: 11/24/2022]
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10
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Lee SH, Wang H, Labroli M, Koseoglu S, Zuck P, Mayhood T, Gill C, Mann P, Sher X, Ha S, Yang SW, Mandal M, Yang C, Liang L, Tan Z, Tawa P, Hou Y, Kuvelkar R, DeVito K, Wen X, Xiao J, Batchlett M, Balibar CJ, Liu J, Xiao J, Murgolo N, Garlisi CG, Sheth PR, Flattery A, Su J, Tan C, Roemer T. TarO-specific inhibitors of wall teichoic acid biosynthesis restore β-lactam efficacy against methicillin-resistant staphylococci. Sci Transl Med 2016; 8:329ra32. [PMID: 26962156 DOI: 10.1126/scitranslmed.aad7364] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The widespread emergence of methicillin-resistant Staphylococcus aureus (MRSA) has dramatically eroded the efficacy of current β-lactam antibiotics and created an urgent need for new treatment options. We report an S. aureus phenotypic screening strategy involving chemical suppression of the growth inhibitory consequences of depleting late-stage wall teichoic acid biosynthesis. This enabled us to identify early-stage pathway-specific inhibitors of wall teichoic acid biosynthesis predicted to be chemically synergistic with β-lactams. We demonstrated by genetic and biochemical means that each of the new chemical series discovered, herein named tarocin A and tarocin B, inhibited the first step in wall teichoic acid biosynthesis (TarO). Tarocins do not have intrinsic bioactivity but rather demonstrated potent bactericidal synergy in combination with broad-spectrum β-lactam antibiotics against diverse clinical isolates of methicillin-resistant staphylococci as well as robust efficacy in a murine infection model of MRSA. Tarocins and other inhibitors of wall teichoic acid biosynthesis may provide a rational strategy to develop Gram-positive bactericidal β-lactam combination agents active against methicillin-resistant staphylococci.
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Affiliation(s)
- Sang Ho Lee
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Hao Wang
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Marc Labroli
- Merck Research Laboratories, West Point, PA 19486, USA
| | | | - Paul Zuck
- Merck Research Laboratories, West Point, PA 19486, USA
| | - Todd Mayhood
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Charles Gill
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Paul Mann
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Xinwei Sher
- Merck Research Laboratories, Boston, MA 02115, USA
| | - Sookhee Ha
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Shu-Wei Yang
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Mihir Mandal
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | - Lianzhu Liang
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Zheng Tan
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Paul Tawa
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Yan Hou
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | | | - Xiujuan Wen
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jing Xiao
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | | | - Jenny Liu
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jianying Xiao
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | | | | | - Payal R Sheth
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Amy Flattery
- Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jing Su
- Merck Research Laboratories, Kenilworth, NJ 07033, USA.
| | | | - Terry Roemer
- Merck Research Laboratories, Kenilworth, NJ 07033, USA.
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11
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Dual Targeting of Cell Wall Precursors by Teixobactin Leads to Cell Lysis. Antimicrob Agents Chemother 2016; 60:6510-6517. [PMID: 27550357 DOI: 10.1128/aac.01050-16] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/06/2016] [Indexed: 01/29/2023] Open
Abstract
Teixobactin represents the first member of a newly discovered class of antibiotics that act through inhibition of cell wall synthesis. Teixobactin binds multiple bactoprenol-coupled cell wall precursors, inhibiting both peptidoglycan and teichoic acid synthesis. Here, we show that the impressive bactericidal activity of teixobactin is due to the synergistic inhibition of both targets, resulting in cell wall damage, delocalization of autolysins, and subsequent cell lysis. We also find that teixobactin does not bind mature peptidoglycan, further increasing its activity at high cell densities and against vancomycin-intermediate Staphylococcus aureus (VISA) isolates with thickened peptidoglycan layers. These findings add to the attractiveness of teixobactin as a potential therapeutic agent for the treatment of infection caused by antibiotic-resistant Gram-positive pathogens.
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12
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Li L, Cheung A, Bayer AS, Chen L, Abdelhady W, Kreiswirth BN, Yeaman MR, Xiong YQ. The Global Regulon sarA Regulates β-Lactam Antibiotic Resistance in Methicillin-Resistant Staphylococcus aureus In Vitro and in Endovascular Infections. J Infect Dis 2016; 214:1421-1429. [PMID: 27543672 DOI: 10.1093/infdis/jiw386] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/11/2016] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The global regulator sarA modulates virulence of methicillin-resistant Staphylococcus aureus (MRSA) via regulation of principal virulence factors (eg, adhesins and toxins) and biofilm formation. Resistance of S. aureus strains to β-lactam antibiotics (eg, oxacillin) depends on the production of penicillin-binding protein 2a (PBP2a), encoded by mecA METHODS: In the present study, we investigated the impact of sarA on the phenotypic and genotypic characteristics of oxacillin resistance both in vitro and in an experimental endocarditis model, using prototypic healthcare- and community-associated MRSA parental and their respective sarA mutant strain sets. RESULTS All sarA mutants (vs respective MRSA parental controls) displayed significant reductions in oxacillin resistance and biofilm formation in vitro and oxacillin persistence in an experimental endocarditis model in vivo. These phenotypes corresponded to reduced mecA expression and PBP2a production and an interdependency of sarA and sigB regulators. Moreover, RNA sequencing analyses showed that sarA mutants exhibited significantly increased levels of primary extracellular proteases and suppressed pyrimidine biosynthetic pathway, argininosuccinate lyase-encoding, and ABC transporter-related genes as compared to the parental strain. CONCLUSIONS These results suggested that sarA regulates oxacillin resistance in mecA-positive MRSA. Thus, abrogation of this regulator represents an attractive and novel drug target to potentiate efficacy of existing antibiotic for MRSA therapy.
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Affiliation(s)
- Liang Li
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center
| | | | - Arnold S Bayer
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Liang Chen
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark
| | - Wessam Abdelhady
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center
| | - Barry N Kreiswirth
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark
| | - Michael R Yeaman
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,Division of Molecular Medicine, Los Angeles County-Harbor-UCLA Medical Center, Torrance.,David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Yan Q Xiong
- Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center.,Division of Infectious Diseases.,David Geffen School of Medicine at UCLA, Los Angeles, California
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13
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Labroli MA, Caldwell JP, Yang C, Lee SH, Wang H, Koseoglu S, Mann P, Yang SW, Xiao J, Garlisi CG, Tan C, Roemer T, Su J. Discovery of potent wall teichoic acid early stage inhibitors. Bioorg Med Chem Lett 2016; 26:3999-4002. [DOI: 10.1016/j.bmcl.2016.06.090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 06/28/2016] [Accepted: 06/29/2016] [Indexed: 10/21/2022]
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14
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SpoVG Regulates Cell Wall Metabolism and Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus Strain N315. Antimicrob Agents Chemother 2016; 60:3455-61. [PMID: 27001809 DOI: 10.1128/aac.00026-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/17/2016] [Indexed: 01/07/2023] Open
Abstract
Increasing cases of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) strains in healthy individuals have raised concerns worldwide. MRSA strains are resistant to almost the entire family of β-lactam antibiotics due to the acquisition of an extra penicillin-binding protein, PBP2a. Studies have shown that spoVG is involved in oxacillin resistance, while the regulatory mechanism remains elusive. In this study, we have found that SpoVG plays a positive role in oxacillin resistance through promoting cell wall synthesis and inhibiting cell wall degradation in MRSA strain N315. Deletion of spoVG in strain N315 led to a significant decrease in oxacillin resistance and a dramatic increase in Triton X-100-induced autolytic activity simultaneously. Real-time quantitative reverse transcription-PCR revealed that the expression of 8 genes related to cell wall metabolism or oxacillin resistance was altered in the spoVG mutant. Electrophoretic mobility shift assay indicated that SpoVG can directly bind to the putative promoter regions of lytN (murein hydrolase), femA, and lytSR (the two-component system). These findings suggest a molecular mechanism in which SpoVG modulates oxacillin resistance by regulating cell wall metabolism in MRSA.
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15
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Mann PA, Müller A, Wolff KA, Fischmann T, Wang H, Reed P, Hou Y, Li W, Müller CE, Xiao J, Murgolo N, Sher X, Mayhood T, Sheth PR, Mirza A, Labroli M, Xiao L, McCoy M, Gill CJ, Pinho MG, Schneider T, Roemer T. Chemical Genetic Analysis and Functional Characterization of Staphylococcal Wall Teichoic Acid 2-Epimerases Reveals Unconventional Antibiotic Drug Targets. PLoS Pathog 2016; 12:e1005585. [PMID: 27144276 PMCID: PMC4856313 DOI: 10.1371/journal.ppat.1005585] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 03/29/2016] [Indexed: 11/18/2022] Open
Abstract
Here we describe a chemical biology strategy performed in Staphylococcus aureus and Staphylococcus epidermidis to identify MnaA, a 2-epimerase that we demonstrate interconverts UDP-GlcNAc and UDP-ManNAc to modulate substrate levels of TarO and TarA wall teichoic acid (WTA) biosynthesis enzymes. Genetic inactivation of mnaA results in complete loss of WTA and dramatic in vitro β-lactam hypersensitivity in methicillin-resistant S. aureus (MRSA) and S. epidermidis (MRSE). Likewise, the β-lactam antibiotic imipenem exhibits restored bactericidal activity against mnaA mutants in vitro and concomitant efficacy against 2-epimerase defective strains in a mouse thigh model of MRSA and MRSE infection. Interestingly, whereas MnaA serves as the sole 2-epimerase required for WTA biosynthesis in S. epidermidis, MnaA and Cap5P provide compensatory WTA functional roles in S. aureus. We also demonstrate that MnaA and other enzymes of WTA biosynthesis are required for biofilm formation in MRSA and MRSE. We further determine the 1.9Å crystal structure of S. aureus MnaA and identify critical residues for enzymatic dimerization, stability, and substrate binding. Finally, the natural product antibiotic tunicamycin is shown to physically bind MnaA and Cap5P and inhibit 2-epimerase activity, demonstrating that it inhibits a previously unanticipated step in WTA biosynthesis. In summary, MnaA serves as a new Staphylococcal antibiotic target with cognate inhibitors predicted to possess dual therapeutic benefit: as combination agents to restore β-lactam efficacy against MRSA and MRSE and as non-bioactive prophylactic agents to prevent Staphylococcal biofilm formation. Staphylococcus aureus and Staphylococcus epidermidis cause life-threatening infections that are commonly acquired in hospitals as well as the community and remain difficult to treat with current antibiotics. In part, this is due to the emergence of methicillin-resistant S. aureus and S. epidermidis (MRSA and MRSE), which exhibit broad resistance to β-lactams such as penicillin and other members of this important founding class of antibiotics. Compounding this problem, Staphylococci commonly colonize the surface of catheters and other medical devices, forming bacterial communities that are intrinsically resistant to antibiotics. Here we functionally characterize a family of 2-epimerases, named MnaA and Cap5P, that we demonstrate by genetic, biochemical, and X-ray crystallography means are essential for wall teichoic acid biosynthesis and that upon their genetic inactivation render methicillin-resistant Staphylococci unable to form biofilms as well as broadly hypersusceptible to β-lactam antibiotics both in vitro and in a host infection setting. WTA 2-epimerases therefore constitute a novel class of methicillin-resistant Staphylococcal drug targets.
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Affiliation(s)
- Paul A. Mann
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Anna Müller
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
- German Centre for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany
| | - Kerstin A. Wolff
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Thierry Fischmann
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Hao Wang
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Patricia Reed
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Yan Hou
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Wenjin Li
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry, University of Bonn, Bonn, Germany
| | - Christa E. Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry, University of Bonn, Bonn, Germany
| | - Jianying Xiao
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Nicholas Murgolo
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Xinwei Sher
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Todd Mayhood
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Payal R. Sheth
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Asra Mirza
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Marc Labroli
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Li Xiao
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Mark McCoy
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Charles J. Gill
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
| | - Mariana G. Pinho
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
- German Centre for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany
| | - Terry Roemer
- Merck Research Laboratories, Kenilworth New Jersey, United States of America
- * E-mail:
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16
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Klahn P, Brönstrup M. New Structural Templates for Clinically Validated and Novel Targets in Antimicrobial Drug Research and Development. Curr Top Microbiol Immunol 2016; 398:365-417. [PMID: 27704270 DOI: 10.1007/82_2016_501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The development of bacterial resistance against current antibiotic drugs necessitates a continuous renewal of the arsenal of efficacious drugs. This imperative has not been met by the output of antibiotic research and development of the past decades for various reasons, including the declining efforts of large pharma companies in this area. Moreover, the majority of novel antibiotics are chemical derivatives of existing structures that represent mostly step innovations, implying that the available chemical space may be exhausted. This review negates this impression by showcasing recent achievements in lead finding and optimization of antibiotics that have novel or unexplored chemical structures. Not surprisingly, many of the novel structural templates like teixobactins, lysocin, griselimycin, or the albicidin/cystobactamid pair were discovered from natural sources. Additional compounds were obtained from the screening of synthetic libraries and chemical synthesis, including the gyrase-inhibiting NTBI's and spiropyrimidinetrione, the tarocin and targocil inhibitors of wall teichoic acid synthesis, or the boronates and diazabicyclo[3.2.1]octane as novel β-lactamase inhibitors. A motif that is common to most clinically validated antibiotics is that they address hotspots in complex biosynthetic machineries, whose functioning is essential for the bacterial cell. Therefore, an introduction to the biological targets-cell wall synthesis, topoisomerases, the DNA sliding clamp, and membrane-bound electron transport-is given for each of the leads presented here.
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Affiliation(s)
- Philipp Klahn
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124, Braunschweig, Germany.
| | - Mark Brönstrup
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124, Braunschweig, Germany.
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17
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Koç C, Gerlach D, Beck S, Peschel A, Xia G, Stehle T. Structural and enzymatic analysis of TarM glycosyltransferase from Staphylococcus aureus reveals an oligomeric protein specific for the glycosylation of wall teichoic acid. J Biol Chem 2015; 290:9874-85. [PMID: 25697358 DOI: 10.1074/jbc.m114.619924] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Indexed: 01/01/2023] Open
Abstract
Anionic glycopolymers known as wall teichoic acids (WTAs) functionalize the peptidoglycan layers of many Gram-positive bacteria. WTAs play central roles in many fundamental aspects of bacterial physiology, and they are important determinants of pathogenesis and antibiotic resistance. A number of enzymes that glycosylate WTA in Staphylococcus aureus have recently been identified. Among these is the glycosyltransferase TarM, a component of the WTA de novo biosynthesis pathway. TarM performs the synthesis of α-O-N-acetylglycosylated poly-5'-phosphoribitol in the WTA structure. We have solved the crystal structure of TarM at 2.4 Å resolution, and we have also determined a structure of the enzyme in complex with its substrate UDP-GlcNAc at 2.8 Å resolution. The protein assembles into a propeller-like homotrimer in which each blade contains a GT-B-type glycosyltransferase domain with a typical Rossmann fold. The enzymatic reaction retains the stereochemistry of the anomeric center of the transferred GlcNAc-moiety on the polyribitol backbone. TarM assembles into a trimer using a novel trimerization domain, here termed the HUB domain. Structure-guided mutagenesis experiments of TarM identify residues critical for enzyme activity, assign a putative role for the HUB in TarM function, and allow us to propose a likely reaction mechanism.
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Affiliation(s)
- Cengiz Koç
- From the Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany
| | - David Gerlach
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Section, University of Tübingen, 72076 Tübingen, Germany
| | - Sebastian Beck
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Section, University of Tübingen, 72076 Tübingen, Germany
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Section, University of Tübingen, 72076 Tübingen, Germany, German Center for Infection Research (DZIF), Partner site Tübingen, 72076 Tübingen, Germany
| | - Guoqing Xia
- Interfaculty Institute of Microbiology and Infection Medicine, Cellular and Molecular Microbiology Section, University of Tübingen, 72076 Tübingen, Germany, Faculty of Medical and Human Sciences, Stopford Building, Institute of Inflammation and Repair, The University of Manchester, Oxford Road, Manchester, M13 9PT, United Kingdom, and
| | - Thilo Stehle
- From the Interfaculty Institute of Biochemistry, University of Tübingen, 72076 Tübingen, Germany, German Center for Infection Research (DZIF), Partner site Tübingen, 72076 Tübingen, Germany, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennesse 37232
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18
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β-Lactam resistance in methicillin-resistant Staphylococcus aureus USA300 is increased by inactivation of the ClpXP protease. Antimicrob Agents Chemother 2014; 58:4593-603. [PMID: 24867990 DOI: 10.1128/aac.02802-14] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) has acquired the mecA gene encoding a peptidoglycan transpeptidase, penicillin binding protein 2a (PBP2a), which has decreased affinity for β-lactams. Quickly spreading and highly virulent community-acquired (CA) MRSA strains recently emerged as a frequent cause of infection in individuals without exposure to the health care system. In this study, we found that the inactivation of the components of the ClpXP protease substantially increased the β-lactam resistance level of a CA-MRSA USA300 strain, suggesting that the proteolytic activity of ClpXP controls one or more pathways modulating β-lactam resistance. These pathways do not involve the control of mecA expression, as the cellular levels of PBP2a were unaltered in the clp mutants. An analysis of the cell envelope properties of the clpX and clpP mutants revealed a number of distinct phenotypes that may contribute to the enhanced β-lactam tolerance. Both mutants displayed significantly thicker cell walls, increased peptidoglycan cross-linking, and altered composition of monomeric muropeptide species compared to those of the wild types. Moreover, changes in Sle1-mediated peptidoglycan hydrolysis and altered processing of the major autolysin Atl were observed in the clp mutants. In conclusion, the results presented here point to an important role for the ClpXP protease in controlling cell wall metabolism and add novel insights into the molecular factors that determine strain-dependent β-lactam resistance.
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19
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Shiota S, Shimizu M, Sugiyama J, Morita Y, Mizushima T, Tsuchiya T. Mechanisms of Action of Corilagin and Tellimagrandin I That Remarkably Potentiate the Activity of β-Lactams against Methicillin-ResistantStaphylococcus aureus. Microbiol Immunol 2013; 48:67-73. [PMID: 14734860 DOI: 10.1111/j.1348-0421.2004.tb03489.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Corilagin and tellimagrandin I are polyphenols isolated from the extract of Arctostaphylos uvaursi and Rosa canina L. (rose red), respectively. We have reported that corilagin and tellimagrandin I remarkably reduced the minimum inhibitory concentration (MIC) of beta-lactams in methicillin-resistant Staphylococcus aureus(MRSA). In this study, we investigated the effect of corilagin and tellimagrandin I on the penicillin binding protein 2 '(2a) (PBP2 '(PBP2a)) which mainly confers the resistance to beta-lactam antibiotics in MRSA. These compounds when added to the culture medium were found to decrease production of the PBP2 '(PBP2a) slightly. Using BOCILLIN FL, a fluorescent-labeled benzyl penicillin, we found that PBP2 '(PBP2a) in MRSA cells that were grown in medium containing corilagin or tellimagrandin I almost completely lost the ability to bind BOCILLIN FL. The binding activity of PBP2 and PBP3 were also reduced to some extent by these compounds. These results indicate that inactivation of PBPs, especially of PBP2 '(PBP2a), by corilagin or tellimagrandin I is the major reason for the remarkable reduction in the resistance level of beta-lactams in MRSA. Corilagin or tellimagrandin I suppressed the activity of beta-lactamase to some extent.
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Affiliation(s)
- Sumiko Shiota
- Department of Pathogenic Microbiology, School of Pharmacy, Shujitsu University, Okayama, Japan
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20
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Winstel V, Xia G, Peschel A. Pathways and roles of wall teichoic acid glycosylation in Staphylococcus aureus. Int J Med Microbiol 2013; 304:215-21. [PMID: 24365646 DOI: 10.1016/j.ijmm.2013.10.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/21/2013] [Accepted: 10/27/2013] [Indexed: 01/10/2023] Open
Abstract
The thick peptidoglycan layers of Gram-positive bacteria are connected to polyanionic glycopolymers called wall teichoic acids (WTA). Pathogens such as Staphylococcus aureus, Listeria monocytogenes, or Enterococcus faecalis produce WTA with diverse, usually strain-specific structure. Extensive studies on S. aureus WTA mutants revealed important functions of WTA in cell division, growth, morphogenesis, resistance to antimicrobials, and interaction with host or phages. While most of the S. aureus WTA-biosynthetic genes have been identified it remained unclear for long how and why S. aureus glycosylates WTA with α- or β-linked N-acetylglucosamine (GlcNAc). Only recently the discovery of two WTA glycosyltransferases, TarM and TarS, yielded fundamental insights into the roles of S. aureus WTA glycosylation. Mutants lacking WTA GlcNAc are resistant towards most of the S. aureus phages and, surprisingly, TarS-mediated WTA β-O-GlcNAc modification is essential for β-lactam resistance in methicillin-resistant S. aureus. Notably, S. aureus WTA GlcNAc residues are major antigens and activate the complement system contributing to opsonophagocytosis. WTA glycosylation with a variety of sugars and corresponding glycosyltransferases were also identified in other Gram-positive bacteria, which paves the way for detailed investigations on the diverse roles of WTA modification with sugar residues.
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Affiliation(s)
- Volker Winstel
- Cellular and Molecular Microbiology Division, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Elfriede-Aulhorn-Straße 6, 72076 Tübingen, Germany; German Center for Infection Research (DZIF), partner site Tübingen, Germany
| | - Guoqing Xia
- Cellular and Molecular Microbiology Division, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Elfriede-Aulhorn-Straße 6, 72076 Tübingen, Germany; German Center for Infection Research (DZIF), partner site Tübingen, Germany.
| | - Andreas Peschel
- Cellular and Molecular Microbiology Division, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Elfriede-Aulhorn-Straße 6, 72076 Tübingen, Germany; German Center for Infection Research (DZIF), partner site Tübingen, Germany
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21
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Sewell EWC, Brown ED. Taking aim at wall teichoic acid synthesis: new biology and new leads for antibiotics. J Antibiot (Tokyo) 2013; 67:43-51. [PMID: 24169797 DOI: 10.1038/ja.2013.100] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/04/2013] [Accepted: 09/10/2013] [Indexed: 11/09/2022]
Abstract
Wall teichoic acids are a major and integral component of the Gram-positive cell wall. These structures are present across all species of Gram-positive bacteria and constitute roughly half of the cell wall. Despite decades of careful investigation, a definitive physiological function for wall teichoic acids remains elusive. Advances in the genetics and biochemistry of wall teichoic acid synthesis have led to a new understanding of the complexity of cell wall synthesis in Gram-positive bacteria. Indeed, these innovations have provided new molecular tools available to probe the synthesis and function of these cell wall structures. Among recent discoveries are unexpected roles for wall teichoic acid in cell division, coordination of peptidoglycan synthesis and β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA). Notably, wall teichoic acid biogenesis has emerged as a bona fide drug target in S. aureus, where remarkable synthetic-viable interactions among biosynthetic genes have been leveraged for the discovery and characterization of novel inhibitors of the pathway.
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Affiliation(s)
- Edward W C Sewell
- Michael G DeGroote Institute for Infectious Disease Research and the Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Eric D Brown
- Michael G DeGroote Institute for Infectious Disease Research and the Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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22
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Dengler V, McCallum N, Kiefer P, Christen P, Patrignani A, Vorholt JA, Berger-Bächi B, Senn MM. Mutation in the C-di-AMP cyclase dacA affects fitness and resistance of methicillin resistant Staphylococcus aureus. PLoS One 2013; 8:e73512. [PMID: 24013956 PMCID: PMC3754961 DOI: 10.1371/journal.pone.0073512] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 07/22/2013] [Indexed: 01/28/2023] Open
Abstract
Faster growing and more virulent strains of methicillin resistant Staphylococcus aureus (MRSA) are increasingly displacing highly resistant MRSA. Elevated fitness in these MRSA is often accompanied by decreased and heterogeneous levels of methicillin resistance; however, the mechanisms for this phenomenon are not yet fully understood. Whole genome sequencing was used to investigate the genetic basis of this apparent correlation, in an isogenic MRSA strain pair that differed in methicillin resistance levels and fitness, with respect to growth rate. Sequencing revealed only one single nucleotide polymorphism (SNP) in the diadenylate cyclase gene dacA in the faster growing but less resistant strain. Diadenylate cyclases were recently discovered to synthesize the new second messenger cyclic diadenosine monophosphate (c-di-AMP). Introduction of this mutation into the highly resistant but slower growing strain reduced resistance and increased its growth rate, suggesting a direct connection between the dacA mutation and the phenotypic differences of these strains. Quantification of cellular c-di-AMP revealed that the dacA mutation decreased c-di-AMP levels resulting in reduced autolysis, increased salt tolerance and a reduction in the basal expression of the cell wall stress stimulon. These results indicate that c-di-AMP affects cell envelope-related signalling in S. aureus. The influence of c-di-AMP on growth rate and methicillin resistance in MRSA indicate that altering c-di-AMP levels could be a mechanism by which MRSA strains can increase their fitness levels by reducing their methicillin resistance levels.
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Affiliation(s)
- Vanina Dengler
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Nadine McCallum
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
- Sydney Emerging Infectious Diseases and Biosecurity Institute (SEIB), University of Sydney, Sydney, Australia
| | - Patrick Kiefer
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | | | - Andrea Patrignani
- Functional Genomics Center Zurich, University/ETH Zurich, Zurich, Switzerland
| | | | | | - Maria M. Senn
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
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23
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Roemer T, Schneider T, Pinho MG. Auxiliary factors: a chink in the armor of MRSA resistance to β-lactam antibiotics. Curr Opin Microbiol 2013; 16:538-48. [PMID: 23895826 DOI: 10.1016/j.mib.2013.06.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/28/2013] [Accepted: 06/28/2013] [Indexed: 12/20/2022]
Abstract
Combination agents provide an important orthogonal approach to treat infectious diseases, particularly those caused by drug resistant pathogens. Indeed, applying a biologically 'rational' and systems-level paradigm to discover potent, selective, and synergistic agents would augment current (and arguably overly relied upon) empirical and serendipitous approaches to such discovery efforts. Here, we review the cellular mechanisms of β-lactam drug resistance and tolerance achieved amongst methicillin-resistant Staphylococcus aureus (MRSA) as well as their molecular targets and strategies to identify cognate inhibitors as potential combination agents to restore β-lactam efficacy against MRSA.
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Affiliation(s)
- Terry Roemer
- Infectious Disease Research, Merck Research Laboratories, Kenilworth, NJ 07033, USA.
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24
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Farha MA, Leung A, Sewell EW, D’Elia MA, Allison SE, Ejim L, Pereira PM, Pinho MG, Wright GD, Brown ED. Inhibition of WTA synthesis blocks the cooperative action of PBPs and sensitizes MRSA to β-lactams. ACS Chem Biol 2013; 8:226-33. [PMID: 23062620 PMCID: PMC3552485 DOI: 10.1021/cb300413m] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Rising drug resistance is limiting treatment options
for infections
by methicillin-resistant Staphylococcus aureus (MRSA).
Herein we provide new evidence that wall teichoic acid (WTA) biogenesis
is a remarkable antibacterial target with the capacity to destabilize
the cooperative action of penicillin-binding proteins (PBPs) that
underlie β-lactam resistance in MRSA. Deletion of gene tarO, encoding the first step of WTA synthesis, resulted
in the restoration of sensitivity of MRSA to a unique profile of β-lactam
antibiotics with a known selectivity for penicillin binding protein
2 (PBP2). Of these, cefuroxime was used as a probe to screen for previously
approved drugs with a cryptic capacity to potentiate its activity
against MRSA. Ticlopidine, the antiplatelet drug Ticlid, strongly
potentiated cefuroxime, and this synergy was abolished in strains
lacking tarO. The combination was also effective
in a Galleria mellonella model of infection. Using
both genetic and biochemical strategies, we determined the molecular
target of ticlopidine as the N-acetylglucosamine-1-phosphate
transferase encoded in gene tarO and provide evidence
that WTA biogenesis represents an Achilles heel supporting the cooperative
function of PBP2 and PBP4 in creating highly cross-linked muropeptides
in the peptidoglycan of S. aureus. This approach
represents a new paradigm to tackle MRSA infection.
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Affiliation(s)
- Maya A. Farha
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Alexander Leung
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Edward W. Sewell
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Michael A. D’Elia
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Sarah E. Allison
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Linda Ejim
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Pedro M. Pereira
- Laboratory of Bacterial Cell
Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Mariana G. Pinho
- Laboratory of Bacterial Cell
Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Gerard D. Wright
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Eric D. Brown
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
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25
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Abstract
The peptidoglycan layers of many gram-positive bacteria are densely functionalized with anionic glycopolymers known as wall teichoic acids (WTAs). These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of gram-positive bacterial physiology. Additionally, WTAs are important in pathogenesis and play key roles in antibiotic resistance. We provide an overview of WTA structure and biosynthesis, review recent studies on the biological roles of these polymers, and highlight remaining questions. We also discuss prospects for exploiting WTA biosynthesis as a target for new therapies to overcome resistant infections.
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Affiliation(s)
- Stephanie Brown
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115;
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26
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Methicillin resistance in Staphylococcus aureus requires glycosylated wall teichoic acids. Proc Natl Acad Sci U S A 2012; 109:18909-14. [PMID: 23027967 DOI: 10.1073/pnas.1209126109] [Citation(s) in RCA: 200] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus peptidoglycan (PG) is densely functionalized with anionic polymers called wall teichoic acids (WTAs). These polymers contain three tailoring modifications: d-alanylation, α-O-GlcNAcylation, and β-O-GlcNAcylation. Here we describe the discovery and biochemical characterization of a unique glycosyltransferase, TarS, that attaches β-O-GlcNAc (β-O-N-acetyl-D-glucosamine) residues to S. aureus WTAs. We report that methicillin resistant S. aureus (MRSA) is sensitized to β-lactams upon tarS deletion. Unlike strains completely lacking WTAs, which are also sensitive to β-lactams, ΔtarS strains have no growth or cell division defects. Because neither α-O-GlcNAc nor β-O-Glucose modifications can confer resistance, the resistance phenotype requires a highly specific chemical modification of the WTA backbone, β-O-GlcNAc residues. These data suggest β-O-GlcNAcylated WTAs scaffold factors required for MRSA resistance. The β-O-GlcNAc transferase identified here, TarS, is a unique target for antimicrobials that sensitize MRSA to β-lactams.
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27
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Zhao Y, Verma V, Belcheva A, Singh A, Fridman M, Golemi-Kotra D. Staphylococcus aureus methicillin-resistance factor fmtA is regulated by the global regulator SarA. PLoS One 2012; 7:e43998. [PMID: 22952845 PMCID: PMC3431356 DOI: 10.1371/journal.pone.0043998] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 07/26/2012] [Indexed: 11/30/2022] Open
Abstract
fmtA encodes a low-affinity penicillin binding protein in Staphylococcus aureus. It is part of the core cell wall stimulon and is involved in methicillin resistance in S. aureus. Here, we report that the transcription factor, SarA, a pleiotropic regulator of virulence genes in S. aureus, regulates the expression of fmtA. In vitro binding studies with purified SarA revealed that it binds to specific sites within the 541-bp promoter region of fmtA. Mutation of a key residue of the regulatory activity of SarA (Arg90) abolished binding of SarA to the fmtA promoter, suggesting that SarA binds specifically to the fmtA promoter region. In vivo analysis of the fmtA promoter using a lux operon reporter fusion show high level expression following oxacillin induction, which was abrogated in a sarA mutant strain. These data suggest that SarA is essential for the induction of fmtA expression by cell wall-specific antibiotics. Further, in vitro transcription studies show that SarA enhances fmtA transcription and suggest that regulation of fmtA could be via a SigA-dependent mechanism. Overall, our results show that SarA plays a direct role in the regulation of fmtA expression via binding to the fmtA promoter.
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Affiliation(s)
- Yinglu Zhao
- Department of Chemistry, York University, Toronto, Ontario, Canada
| | - Vidhu Verma
- Department of Chemistry, York University, Toronto, Ontario, Canada
| | | | - Atul Singh
- Department of Chemistry, York University, Toronto, Ontario, Canada
| | - Michael Fridman
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Dasantila Golemi-Kotra
- Department of Biology, York University, Toronto, Ontario, Canada
- Department of Chemistry, York University, Toronto, Ontario, Canada
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28
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Pozzi C, Waters EM, Rudkin JK, Schaeffer CR, Lohan AJ, Tong P, Loftus BJ, Pier GB, Fey PD, Massey RC, O'Gara JP. Methicillin resistance alters the biofilm phenotype and attenuates virulence in Staphylococcus aureus device-associated infections. PLoS Pathog 2012; 8:e1002626. [PMID: 22496652 PMCID: PMC3320603 DOI: 10.1371/journal.ppat.1002626] [Citation(s) in RCA: 214] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 02/23/2012] [Indexed: 01/15/2023] Open
Abstract
Clinical isolates of Staphylococcus aureus can express biofilm phenotypes promoted by the major cell wall autolysin and the fibronectin-binding proteins or the icaADBC-encoded polysaccharide intercellular adhesin/poly-N-acetylglucosamine (PIA/PNAG). Biofilm production in methicillin-susceptible S. aureus (MSSA) strains is typically dependent on PIA/PNAG whereas methicillin-resistant isolates express an Atl/FnBP-mediated biofilm phenotype suggesting a relationship between susceptibility to β-lactam antibiotics and biofilm. By introducing the methicillin resistance gene mecA into the PNAG-producing laboratory strain 8325-4 we generated a heterogeneously resistant (HeR) strain, from which a homogeneous, high-level resistant (HoR) derivative was isolated following exposure to oxacillin. The HoR phenotype was associated with a R602H substitution in the DHHA1 domain of GdpP, a recently identified c-di-AMP phosphodiesterase with roles in resistance/tolerance to β-lactam antibiotics and cell envelope stress. Transcription of icaADBC and PNAG production were impaired in the 8325-4 HoR derivative, which instead produced a proteinaceous biofilm that was significantly inhibited by antibodies against the mecA-encoded penicillin binding protein 2a (PBP2a). Conversely excision of the SCCmec element in the MRSA strain BH1CC resulted in oxacillin susceptibility and reduced biofilm production, both of which were complemented by mecA alone. Transcriptional activity of the accessory gene regulator locus was also repressed in the 8325-4 HoR strain, which in turn was accompanied by reduced protease production and significantly reduced virulence in a mouse model of device infection. Thus, homogeneous methicillin resistance has the potential to affect agr- and icaADBC-mediated phenotypes, including altered biofilm expression and virulence, which together are consistent with the adaptation of healthcare-associated MRSA strains to the antibiotic-rich hospital environment in which they are frequently responsible for device-related infections in immuno-compromised patients. The acquisition of mecA, which encodes penicillin binding protein 2a (PBP2a) and methicillin resistance, by Staphylococcus aureus has added to an already impressive array of virulence mechanisms including enzyme and toxin production, biofilm forming capacity and immune evasion. And yet clinical data does not indicate that healthcare-associated methicillin resistant S. aureus (MRSA) strains are more virulent than their methicillin-susceptible counterparts. Here our findings suggest that MRSA sacrifices virulence potential for antibiotic resistance and that expression of methicillin resistance alters the biofilm phenotype but does not interfere with the colonization of implanted medical devices in vivo. High level expression of PBP2a, which was associated with a mutation in the c-di-AMP phosphodiesterase gene gdpP, resulted in these pleiotrophic effects by blocking icaADBC-dependent polysaccharide type biofilm development and promoting an alternative PBP2a-mediated biofilm, repressing the accessory gene regulator and extracellular protease production, and attenuating virulence in a mouse device-infection model. Thus the adaptation of MRSA to the hospital environment has apparently focused on the acquisition of antibiotic resistance and retention of biofilm forming capacity, which are likely to be more advantageous than metabolically-expensive enzyme and toxin production in immunocompromised patients with implanted medical devices offering a route to infection.
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Affiliation(s)
- Clarissa Pozzi
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Elaine M. Waters
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Justine K. Rudkin
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Carolyn R. Schaeffer
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Amanda J. Lohan
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Pin Tong
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Brendan J. Loftus
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Gerald B. Pier
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Paul D. Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Ruth C. Massey
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - James P. O'Gara
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
- * E-mail:
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29
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Monteiro R, Vitorino R, Domingues P, Radhouani H, Carvalho C, Poeta P, Torres C, Igrejas G. Proteome of a methicillin-resistant Staphylococcus aureus clinical strain of sequence type ST398. J Proteomics 2012; 75:2892-915. [PMID: 22245554 DOI: 10.1016/j.jprot.2011.12.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/20/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
Abstract
Proteomics is a powerful tool to analyze the differences in gene expression of bacterial strains. Staphylococcus aureus has long been recognized as an important pathogen in human disease. In order to investigate this pathogen, the proteome of a clinical methicillin-resistant S. aureus (MRSA) strain of the sequence type ST398 was determined using 2-DE. Using 2-DE we obtained a total of 105 spots the MRSA strain. Furthermore in correlation with bioinformatic databases, they allowed accurate identification and characterization of proteins, resulting in 227 identified proteins. There were found proteins related to basic function of the cell, but also proteins related to virulence like catalase, specific of S. aureus species, and proteins related to antibiotic resistance. Proteins associated with antibiotic resistance or virulence factors are related to genomic databases. The most abundant classes identified involved glycolysis, energy production, one-carbon metabolism, and oxidation-reduction process, all of which reflect an active metabolism. These results highlight the importance of proteomics to deepen in the knowledge of protein expression of MRSA strain of the lineage ST398, microorganism with diverse and important resistance mechanisms. With this proteome map we have an essential tool for a better understanding of this pathogen and providing new data for protein databases. This article is part of a Special Issue entitled: Proteomics: The clinical link.
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Affiliation(s)
- R Monteiro
- Department of Genetics and Biotechnology, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal
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Holland LM, Conlon B, O'Gara JP. Mutation of tagO reveals an essential role for wall teichoic acids in Staphylococcus epidermidis biofilm development. Microbiology (Reading) 2011; 157:408-418. [DOI: 10.1099/mic.0.042234-0] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The icaADBC-encoded polysaccharide intercellular adhesin (PIA) and wall teichoic acids (WTA) are structural components of Staphylococcus epidermidis biofilms. Deletion of tagO, which encodes the first enzymic step in WTA biosynthesis, had pleiotropic effects, including enhanced intercellular aggregation and autolytic activity, and impaired biofilm production. The biofilm-negative phenotype of the tagO mutant, named TAGO1, was associated with increased cell surface hydrophobicity, lower rates of primary attachment to polystyrene, and reduced icaADBC operon and PIA expression. Mild acid stress induced by growth in BHI glucose media reduced rates of stationary phase autolysis and enhanced aggregation by TAGO1, leading to formation of a pellicle, which unlike a biofilm was only loosely attached to the polystyrene surface. TAGO1 pellicles were dispersed by proteinase K and DNase I but not sodium metaperiodate, implicating protein and extracellular DNA (eDNA) and not PIA in this phenotype. Substantially increased levels of eDNA were recovered from TAGO1 culture supernatants compared with the wild-type. These data indicate that WTA are essential for the primary attachment and accumulation phases of the S. epidermidis biofilm phenotype. Furthermore, in the absence of WTA, proteins and eDNA can promote cell aggregation and pellicle formation, which also appear to limit interactions with artificial surfaces.
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Affiliation(s)
- Linda M. Holland
- School of Biomolecular and Biomedical Science and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - Brian Conlon
- School of Biomolecular and Biomedical Science and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - James P. O'Gara
- School of Biomolecular and Biomedical Science and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Campbell J, Singh AK, Santa Maria JP, Kim Y, Brown S, Swoboda JG, Mylonakis E, Wilkinson BJ, Walker S. Synthetic lethal compound combinations reveal a fundamental connection between wall teichoic acid and peptidoglycan biosyntheses in Staphylococcus aureus. ACS Chem Biol 2011; 6:106-16. [PMID: 20961110 DOI: 10.1021/cb100269f] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methicillin resistance in Staphylococcus aureus depends on the production of mecA, which encodes penicillin-binding protein 2A (PBP2A), an acquired peptidoglycan transpeptidase (TP) with reduced susceptibility to β-lactam antibiotics. PBP2A cross-links nascent peptidoglycan when the native TPs are inhibited by β-lactams. Although mecA expression is essential for β-lactam resistance, it is not sufficient. Here we show that blocking the expression of wall teichoic acids (WTAs) by inhibiting the first enzyme in the pathway, TarO, sensitizes methicillin-resistant S. aureus (MRSA) strains to β-lactams even though the β-lactam-resistant transpeptidase, PBP2A, is still expressed. The dramatic synergy between TarO inhibitors and β-lactams is noteworthy not simply because strategies to overcome MRSA are desperately needed but because neither TarO nor the activities of the native TPs are essential in MRSA strains. The "synthetic lethality" of inhibiting TarO and the native TPs suggests a functional connection between ongoing WTA expression and peptidoglycan assembly in S. aureus. Indeed, transmission electron microscopy shows that S. aureus cells blocked in WTA synthesis have extensive defects in septation and cell separation, indicating dysregulated cell wall assembly and degradation. Our studies imply that WTAs play a fundamental role in S. aureus cell division and raise the possibility that synthetic lethal compound combinations may have therapeutic utility for overcoming antibiotic-resistant bacterial infections.
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Affiliation(s)
- Jennifer Campbell
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Atul K. Singh
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
- School of Biological Science, Illinois State University, Normal, Illinois 61790, United States
| | - John P. Santa Maria
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Younghoon Kim
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Stephanie Brown
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Jonathan G. Swoboda
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Brian J. Wilkinson
- School of Biological Science, Illinois State University, Normal, Illinois 61790, United States
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
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32
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Essential role for the major autolysin in the fibronectin-binding protein-mediated Staphylococcus aureus biofilm phenotype. Infect Immun 2010; 79:1153-65. [PMID: 21189325 DOI: 10.1128/iai.00364-10] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Staphylococcus aureus clinical isolates are capable of producing at least two distinct types of biofilm mediated by the fibronectin-binding proteins (FnBPs) or the icaADBC-encoded polysaccharide intercellular adhesin (PIA). Deletion of the major autolysin gene atl reduced primary attachment rates and impaired FnBP-dependent biofilm production on hydrophilic polystyrene in 12 clinical methicillin-resistant S. aureus (MRSA) isolates but had no effect on PIA-dependent biofilm production by 9 methicillin-susceptible S. aureus (MSSA) isolates. In contrast, Atl was required for both FnBP- and PIA-mediated biofilm development on hydrophobic polystyrene. Here we investigated the role of Atl in biofilm production on hydrophilic polystyrene. The alternative sigma factor σ(B), which represses RNAIII expression and extracellular protease production, was required for FnBP- but not PIA-dependent biofilm development. Furthermore, mutation of the agr locus enhanced FnBP-dependent biofilm development, whereas a sarA mutation, which increases protease production, blocked FnBP-mediated biofilm development. Mutation of sigB in MRSA isolate BH1CC lowered primary attachment rates, in part via reduced atl transcription. Posttranslational activation or inhibition of Atl activity with phenylmethylsulfonyl fluoride and polyanethole sodium sulfonate or mutation of the Atl amidase active site interfered with lytic activity and biofilm development. Consistent with these observations, extracellular DNA was important for the early stages of Atl/FnBP-dependent biofilm development. Further analysis of atl regulation revealed that atlR encodes a transcriptional repressor of the major autolysin and that an atlR::Tc(r) mutation in BH1CC enhanced biofilm-forming capacity. These data reveal an essential role for the major autolysin in the early events of the FnBP-dependent S. aureus biofilm phenotype.
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33
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In vitro antimicrobial activity of wall teichoic acid biosynthesis inhibitors against Staphylococcus aureus isolates. Antimicrob Agents Chemother 2010; 55:767-74. [PMID: 21098254 DOI: 10.1128/aac.00879-10] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is the leading cause of invasive and superficial human infections, is increasingly antibiotic resistant, and is therefore the target for the development of new antimicrobials. Compounds (1835F03 and targocil) were recently shown to function as bacteriostatic inhibitors of wall teichoic acid (WTA) biosynthesis in S. aureus. To assess the value of targeting WTA biosynthesis in human infection, it was therefore of interest to verify the involvement of WTA in bacterial binding to human corneal epithelial cells (HCECs) and to assess the activities of inhibitors of WTA biosynthesis against clinical isolates of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) from cases of human keratitis. The 1835F03 MIC(90)s were 8 μg/ml for MSSA keratitis isolates and >32 μg/ml for MRSA keratitis isolates. The MIC(90) for the analog of 1835F03, targocil, was 2 μg/ml for both MRSA and MSSA. Targocil exhibited little toxicity at concentrations near the MIC, with increased toxicity occurring at higher concentrations and with longer exposure times. Targocil activity was moderately sensitive to the presence of serum, but it inhibited extracellular and intracellular bacteria in the presence of HCECs better than vancomycin. Targocil-resistant strains exhibited a significantly reduced ability to adhere to HCECs.
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34
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Swoboda JG, Campbell J, Meredith TC, Walker S. Wall teichoic acid function, biosynthesis, and inhibition. Chembiochem 2010; 11:35-45. [PMID: 19899094 DOI: 10.1002/cbic.200900557] [Citation(s) in RCA: 277] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Jonathan G Swoboda
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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35
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Molecular basis and phenotype of methicillin resistance in Staphylococcus aureus and insights into new beta-lactams that meet the challenge. Antimicrob Agents Chemother 2009; 53:4051-63. [PMID: 19470504 DOI: 10.1128/aac.00084-09] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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36
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The Staphylococcus aureus GGDEF domain-containing protein, GdpS, influences protein A gene expression in a cyclic diguanylic acid-independent manner. Infect Immun 2009; 77:2849-56. [PMID: 19380471 DOI: 10.1128/iai.01405-08] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is an important human pathogen that is the principal cause of a variety of diseases, ranging from localized skin infections to life-threatening systemic infections. The success of the organism as a pathogen and its ability to cause such a wide range of infections are due to its extensive virulence factors. In this study, we identified the role of the only GGDEF domain protein (GdpS [GGDEF domain protein from Staphylococcus]) in the virulence of S. aureus NCTC8325. Inactivation of gdpS results in an alteration in the production of a range of virulence factors, such as serine and cysteine proteases, fibrinogen-binding proteins, and, specifically, protein A (Spa), a major surface protein of S. aureus. The transcript level of spa decreases eightfold in the gdpS mutant compared with the parental NCTC8325 strain. Furthermore, the transcript level of sarS, which encodes a direct positive regulator of spa, also decreases in the gdpS mutant compared with the wild type, while the transcript levels of agr, sarA, sarT, and rot display no apparent changes in the gdpS mutant, suggesting that GdpS affects the expression of spa through interaction with SarS by unknown mechanisms. Furthermore, the complementation assays show that the influences of GdpS on spa and sarS depend on its N-terminal domain, which is predicted to be the sensor of a two-component system, rather than its C-terminal GGDEF domain with conserved GGDEF, suggesting that GdpS functions in S. aureus by an unknown mechanism independent of 3',5'-cyclic diguanylic acid signaling.
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37
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Vergara-Irigaray M, Maira-Litrán T, Merino N, Pier GB, Penadés JR, Lasa I. Wall teichoic acids are dispensable for anchoring the PNAG exopolysaccharide to the Staphylococcus aureus cell surface. MICROBIOLOGY-SGM 2008; 154:865-877. [PMID: 18310032 DOI: 10.1099/mic.0.2007/013292-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Biofilm formation in Staphylococcus aureus is usually associated with the production of the poly-N-acetylglucosamine (PNAG) exopolysaccharide, synthesized by proteins encoded by the icaADBC operon. PNAG is a linear beta-(1-6)-linked N-acetylglucosaminoglycan that has to be partially deacetylated and consequently positively charged in order to be associated with bacterial cell surfaces. Here, we investigated whether attachment of PNAG to bacterial surfaces is mediated by ionic interactions with the negative charge of wall teichoic acids (WTAs), which represent the most abundant polyanions of the Gram-positive bacterial envelope. We generated WTA-deficient mutants by in-frame deletion of the tagO gene in two genetically unrelated S. aureus strains. The DeltatagO mutants were more sensitive to high temperatures, showed a higher degree of cell aggregation, had reduced initial adherence to abiotic surfaces and had a reduced capacity to form biofilms under both steady-state and flow conditions. However, the levels as well as the strength of the PNAG interaction with the bacterial cell surface were similar between DeltatagO mutants and their corresponding wild-type strains. Furthermore, double DeltatagO DeltaicaADBC mutants displayed a similar aggregative phenotype to that of single DeltatagO mutants, indicating that PNAG is not responsible for the aggregative behaviour observed in DeltatagO mutants. Overall, the absence of WTAs in S. aureus had little effect on PNAG production or anchoring to the cell surface, but did affect the biofilm-forming capacity, cell aggregative behaviour and the temperature sensitivity/stability of S. aureus.
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Affiliation(s)
- Marta Vergara-Irigaray
- Laboratory of Microbial Biofilms, Instituto de Agrobiotecnología, Universidad Pública de Navarra-CSIC-Gobierno de Navarra, 31006 Pamplona, Spain
| | - Tomas Maira-Litrán
- Channing Laboratory, Department of Medicine, Brigham Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Nekane Merino
- Laboratory of Microbial Biofilms, Instituto de Agrobiotecnología, Universidad Pública de Navarra-CSIC-Gobierno de Navarra, 31006 Pamplona, Spain
| | - Gerald B Pier
- Channing Laboratory, Department of Medicine, Brigham Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - José R Penadés
- Centro de Investigación y Tecnología Animal, Instituto Valenciano de Investigaciones Agrarias (CITA-IVIA), Apdo 187, 12400 Segorbe, Castellón, Spain
| | - Iñigo Lasa
- Laboratory of Microbial Biofilms, Instituto de Agrobiotecnología, Universidad Pública de Navarra-CSIC-Gobierno de Navarra, 31006 Pamplona, Spain
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Staphylococcus aureus clinical isolate with high-level methicillin resistance with an lytH mutation caused by IS1182 insertion. Antimicrob Agents Chemother 2007; 52:643-7. [PMID: 18070966 DOI: 10.1128/aac.00395-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously reported that deficiency of the lytH gene, whose product is homologous to lytic enzymes, caused the elevation of methicillin resistance in Staphylococcus aureus strain SR17238, a strain of S. aureus with a low level of resistance to methicillin (low-level MRSA) (J. Bacteriol. 179:6294-6301, 1997). In this study, we demonstrated that deficiency of lytH caused the same phenomenon in four other clinical isolates of low-level MRSA, suggesting this deficiency to exist in clinical isolates. We therefore searched the region including lytH in 127 clinical isolates of MRSA by PCR and found one strain, SR17164 (methicillin MIC, 1,600 microg/ml), in which the lytH gene was inactivated by insertion sequence IS1182. lytH::IS1182 was replaced with intact lytH in this strain by integration and excision of the plasmid carrying the lytH region. Recombinants with intact lytH genes showed methicillin MICs of 800 microg/ml, twofold lower than those of the recombinants with lytH::IS1182 and the parent. In addition, S. aureus SR17164, which has a high level of methicillin resistance, had properties similar to those caused by lytH deficiency; that is, the resistance levels of strain SR17164 and lytH-deficient variants from strain SR17238 were not significantly affected by llm inactivation, which greatly lowered resistance levels in most other high-level MRSA strains. These findings suggest that lytH inactivation contributed, to some extent, to the resistance level of S. aureus SR17164. To the best of our knowledge, this strain is the first clinical isolate of MRSA for which the genetic base for high-level resistance has been clarified.
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Fan X, Liu Y, Smith D, Konermann L, Siu KWM, Golemi-Kotra D. Diversity of penicillin-binding proteins. Resistance factor FmtA of Staphylococcus aureus. J Biol Chem 2007; 282:35143-52. [PMID: 17925392 DOI: 10.1074/jbc.m706296200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antibiotic-resistant Staphylococcus aureus is a major concern to public health. Methicillin-resistant S. aureus strains are completely resistant to all beta-lactams antibiotics. One of the main factors involved in methicillin resistance in S. aureus is the penicillin-binding protein, PBP2a. This protein is insensitive to inactivation by beta-lactam antibiotics such as methicillin. Although other proteins are implicated in high and homogeneous levels of methicillin resistance, the functions of these other proteins remain elusive. Herein, we report for the first time on the putative function of one of these proteins, FmtA. This protein specifically interacts with beta-lactam antibiotics forming covalently bound complexes. The serine residue present in the sequence motif Ser-X-X-Lys (which is conserved among penicillin-binding proteins and beta-lactamases) is the active-site nucleophile during the formation of acyl-enzyme species. FmtA has a low binding affinity for beta-lactams, and it experiences a slow acylation rate, suggesting that this protein is intrinsically resistant to beta-lactam inactivation. We found that FmtA undergoes conformational changes in presence of beta-lactams that may be essential to the beta-lactam resistance mechanism. FmtA binds to peptidoglycan in vitro. Our findings suggest that FmtA is a penicillin-binding protein, and as such, it may compensate for suppressed peptidoglycan biosynthesis under beta-lactam induced cell wall stress conditions.
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Affiliation(s)
- Xin Fan
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
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40
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Tu Quoc PH, Genevaux P, Pajunen M, Savilahti H, Georgopoulos C, Schrenzel J, Kelley WL. Isolation and characterization of biofilm formation-defective mutants of Staphylococcus aureus. Infect Immun 2006; 75:1079-88. [PMID: 17158901 PMCID: PMC1828571 DOI: 10.1128/iai.01143-06] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Staphylococcus aureus produces biofilm and this mode of colonization facilitates infections that are often difficult to treat and engender high morbidity and mortality. We have exploited bacteriophage Mu transposition methods to create an insertional mutant library in a highly biofilm-forming S. aureus clinical isolate. Our screen identified 38 insertions in 23 distinct genes together with one intergenic region that significantly reduced biofilm formation. Nineteen insertions were mapped in loci not previously known to affect biofilm in this organism. These include insertions in codY, srrA, mgrA, and fmtA, a putative DEAD-box helicase, two members of the zinc-metallo-beta lactamase/beta-CASP family, and a hypothetical protein with a GGDEF motif. Fifteen insertions occurred in the icaADBC operon, which produces intercellular adhesion antigen (PIA) and is important for biofilm formation in many strains of S. aureus and Staphylococcus epidermidis. Obtaining a high proportion of independent Em-Mu disruptions in icaADBC demonstrated both the importance of PIA for biofilm formation in this clinical strain and the strong validation of the screening procedure that concomitantly uncovered additional mutants. All non-ica mutants were further analyzed by immunoblotting and biochemical fractionation for perturbation of PIA and wall teichoic acid. PIA levels were diminished in the majority of non-ica insertional mutants. Three mutant strains were chosen and were functionally complemented for restored biofilm formation by transformation with plasmids carrying the cloned wild-type gene under the control of a xylose-inducible promoter. This is a comprehensive collection of biofilm-defective mutants that underscores the multifactorial genetic program underlying the establishment of biofilm in this insidious pathogen.
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Affiliation(s)
- Patrick H Tu Quoc
- Division of Infectious Diseases, University Hospital of Geneva, 24 rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland
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41
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Renzoni A, Barras C, François P, Charbonnier Y, Huggler E, Garzoni C, Kelley WL, Majcherczyk P, Schrenzel J, Lew DP, Vaudaux P. Transcriptomic and functional analysis of an autolysis-deficient, teicoplanin-resistant derivative of methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 2006; 50:3048-61. [PMID: 16940101 PMCID: PMC1563528 DOI: 10.1128/aac.00113-06] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The molecular basis of glycopeptide-intermediate S. aureus (GISA) isolates is not well defined though frequently involves phenotypes such as thickened cell walls and decreased autolysis. We have exploited an isogenic pair of teicoplanin-susceptible (strain MRGR3) and teicoplanin-resistant (strain 14-4) methicillin-resistant S. aureus strains for detailed transcriptomic profiling and analysis of altered autolytic properties. Strain 14-4 displayed markedly deficient Triton X-100-triggered autolysis compared to its teicoplanin-susceptible parent, although microarray analysis paradoxically did not reveal significant reductions in expression levels of major autolytic genes atl, lytM, and lytN, except for sle1, which showed a slight decrease. The most important paradox was a more-than-twofold increase in expression of the cidABC operon in 14-4 compared to MRGR3, which was correlated with decreased expression of autolysis negative regulators lytSR and lrgAB. In contrast, the autolysis-deficient phenotype of 14-4 was correlated with both increased expression of negative autolysis regulators (arlRS, mgrA, and sarA) and decreased expression of positive regulators (agr RNAII and RNAIII). Quantitative bacteriolytic assays and zymographic analysis of concentrated culture supernatants showed a striking reduction in Atl-derived, extracellular bacteriolytic hydrolase activities in 14-4 compared to MRGR3. This observed difference was independent of the source of cell wall substrate (MRGR3 or 14-4) used for analysis. Collectively, our results suggest that altered autolytic properties in 14-4 are apparently not driven by significant changes in the transcription of key autolytic effectors. Instead, our analysis points to alternate regulatory mechanisms that impact autolysis effectors which may include changes in posttranscriptional processing or export.
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Affiliation(s)
- Adriana Renzoni
- Service of Infectious Diseases, University Hospitals of Geneva, CH-1211 Geneva 14, Switzerland
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42
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Fujita M, Shiota S, Kuroda T, Hatano T, Yoshida T, Mizushima T, Tsuchiya T. Remarkable synergies between baicalein and tetracycline, and baicalein and beta-lactams against methicillin-resistant Staphylococcus aureus. Microbiol Immunol 2005; 49:391-6. [PMID: 15840965 DOI: 10.1111/j.1348-0421.2005.tb03732.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
During the screening of compounds that potentiate the effect of antimicrobial agents against methicillin-resistant Staphylococcus aureus(MRSA), we found that an extract of thyme (Thymus vulgaris L) leaves greatly reduced the minimum inhibitory concentration (MIC) of tetracycline against MRSA. We isolated the effective compound and identified it as baicalein (5, 6, 7-trihydroxyflavone). One of the clinically isolated MRSA strains possessed tetK, a gene encoding active efflux pump for tetracycline. We examined the effect of baicalein on the efflux of tetracycline, using Escherichia coli KAM32/pTZ1252 carrying the tetK. The E. coli KAM32/pTZ1252 showed 8 to 16 times higher MIC than E. coli KAM32. We observed strong inhibition of transport of tetracycline by baicalein with membrane vesicles prepared from E. coli KAM32/pTZ1252. Baicalein also showed synergy with tetracycline in a MRSA strain that doesn't possess tetK, or with beta-lactams. Thus, mechanisms of the synergies seem to be versatile.
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Affiliation(s)
- Mai Fujita
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University, Okayama, Japan
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43
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Price NP, Momany FA. Modeling bacterial UDP-HexNAc: polyprenol-P HexNAc-1-P transferases. Glycobiology 2005; 15:29R-42R. [PMID: 15843595 DOI: 10.1093/glycob/cwi065] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein N-glycosylation in eukaryotes and peptidoglycan biosynthesis in bacteria are both initiated by the transfer of a D-N-acetylhexosamine 1-phosphate to a membrane-bound polyprenol phosphate. These reactions are catalyzed by a family of transmembrane proteins known as the UDP-D-N-acetylhexosamine: polyprenol phosphate D-N-acetylhexosamine 1-phosphate transferases. The sole eukaryotic member of this family, the d-N-acetylglucosamine 1-phosphate transferase (GPT), is specific for UDP-GlcNAc as the donor substrate and uses dolichol phosphate as the membrane-bound acceptor. The bacterial translocases, MraY, WecA, and WbpL, utilize undecaprenol phosphate as the acceptor substrate, but differ in their specificity for the UDP-sugar donor substrate. The structural basis of this sugar nucleotide specificity is uncertain. However, potential carbohydrate recognition (CR) domains have been identified within the C-terminal cytoplasmic loops of MraY, WecA, and WbpL that are highly conserved in family members with the same UDP-N-acetylhexosamine specificity. This review focuses on the catalytic mechanism and substrate specificity of these bacterial UDP-D-N-acetylhexosamine: polyprenol phosphate D-N-acetylhexosamine 1-P transferases and may provide insights for the development of selective inhibitors of cell wall biosynthesis.
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Affiliation(s)
- Neil P Price
- USDA-ARS-NCAUR, Bioproducts and Biocatalysis Research Unit, Peoria, IL, USA.
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44
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High Molecular Weight Plant Poplyphenols (Tannins): Prospective Functions. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0079-9920(05)80008-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
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45
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Rohrer S, Maki H, Berger-Bächi B. What makes resistance to methicillin heterogeneous? J Med Microbiol 2003; 52:605-607. [PMID: 12867551 DOI: 10.1099/jmm.0.05176-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Susanne Rohrer
- University of Zürich, Institute of Medical Microbiology, Gloriastr. 32, CH-8028 Zürich, Switzerland
| | - Hideki Maki
- University of Zürich, Institute of Medical Microbiology, Gloriastr. 32, CH-8028 Zürich, Switzerland
| | - Brigitte Berger-Bächi
- University of Zürich, Institute of Medical Microbiology, Gloriastr. 32, CH-8028 Zürich, Switzerland
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46
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Tajima Y. Effects of tungstosilicate on strains of methicillin-resistant Staphylococcus aureus with unique resistant mechanisms. Microbiol Immunol 2003; 47:207-12. [PMID: 12725290 DOI: 10.1111/j.1348-0421.2003.tb03388.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a previous study, it was found that polyoxotungstates such as undecatungstosilicate (SiW11) greatly sensitized strains of methicillin-resistant Staphylococcus aureus (MRSA) to beta-lactams. In this report, the effects of SiW11 on several MRSA strains with unique resistant mechanisms were studied. SiW11 was still effective to MRSA mutants with higher beta-lactam resistance due to reduced cell-lytic activity. Since the antimicrobial effect of TOC-39 (a cephem antibiotic with strong affinity to penicillin-binding protein (PBP) 2') was not strongly enhanced in any case, it was confirmed that the sensitizing effect of SiW11 is due to reduced expression of PBP2'. However, the sensitizing effect of SiW11 was relatively weak in MRSA strains with lowered susceptibility to glycopeptide antibiotics. A certain resistant mechanism other than the mecA-PBP2' system worked in such a strain. Interestingly, an MRSA mutant with the Eagle-type resistance was dramatically sensitized. This result suggests that SiW11 has another site of action besides reducing the expression of PBP2'.
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Affiliation(s)
- Yutaka Tajima
- Clinical Laboratory, Saga Medical School Hospital, Nabeshima, Saga, Saga 849-8501, Japan.
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47
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Cordwell SJ, Larsen MR, Cole RT, Walsh BJ. Comparative proteomics of Staphylococcus aureus and the response of methicillin-resistant and methicillin-sensitive strains to Triton X-100. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2765-2781. [PMID: 12213923 DOI: 10.1099/00221287-148-9-2765] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Proteomics is a powerful tool for analysing differences in gene expression between bacterial strains with alternate phenotypes. Staphylococcus aureus strains are grouped on the basis of their sensitivity to methicillin. Two-dimensional gel electrophoresis was combined with MS to compare the protein profiles of S. aureus strains COL (methicillin-resistant) and 8325 (methicillin-sensitive). Reference mapping via this approach identified 377 proteins that corresponded to 266 distinct ORFs. Amongst these identified proteins were 14 potential virulence factors. The production of 41 'hypothetical' proteins was confirmed, and eight of these appeared to be unique to S. aureus. Strain COL displayed 12 protein spots, which included alkaline-shock protein 23 (Asp23) and cold-shock proteins CspABC, which either were not present in strain 8325 or were present at a significantly lower intensity in this strain. Comparative maps were used to characterize the S. aureus response to treatment with Triton X-100 (TX-100), a detergent that has been shown to reduce methicillin resistance independently of an interaction with the mecA-encoded penicillin-binding protein 2a. In response to growth of the bacteria in the presence of TX-100, 44 protein spots showed altered levels of abundance, and 11 of these spots were found only in COL. The products of genes regulated by sigma(B) (the alternative sigma factor), including Asp23 and three proteins of unknown function, and SarA (a regulator of virulence genes) were shown to be present at significantly altered levels. SarA production was induced in TX-100-treated cultures. A protein of the sigma(B) operon, RsbV, was only detected in COL and its production was down-regulated in COL when the strain was treated with TX-100, whereas RsbW was present at reduced levels in both strains. Upon growth of both strains in the presence of TX-100, no effects on the production of the essential methicillin-resistance factor FemA were detected, whereas phosphoglucosamine mutase (GlmM) production was reduced in COL alone. This study suggests that proteins of the sigma(B) and sarA regulons, as well as other factors, are involved in methicillin resistance in S. aureus.
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Affiliation(s)
- Stuart J Cordwell
- Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Sydney, Australia21091
| | - Martin R Larsen
- Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Sydney, Australia21091
| | - Rebecca T Cole
- Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Sydney, Australia21091
| | - Bradley J Walsh
- Australian Proteome Analysis Facility, Level 4, Building F7B, Macquarie University, Sydney, Australia21091
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48
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Soldo B, Lazarevic V, Karamata D. tagO is involved in the synthesis of all anionic cell-wall polymers in Bacillus subtilis 168. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2079-2087. [PMID: 12101296 DOI: 10.1099/00221287-148-7-2079] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sequence homologies suggest that the Bacillus subtilis 168 tagO gene encodes UDP-N-acetylglucosamine:undecaprenyl-P N-acetylglucosaminyl 1-P transferase, the enzyme responsible for catalysing the first step in the synthesis of the teichoic acid linkage unit, i.e. the formation of undecaprenyl-PP-N-acetylglucosamine. Inhibition of tagO expression mediated by an IPTG-inducible P(spac) promoter led to the development of a coccoid cell morphology, a feature characteristic of mutants blocked in teichoic acid synthesis. Indeed, analyses of the cell-wall phosphate content, as well as the incorporation of radioactively labelled precursors, revealed that the synthesis of poly(glycerol phosphate) and poly(glucosyl N-acetylgalactosamine 1-phosphate), the two strain 168 teichoic acids known to share the same linkage unit, was affected. Surprisingly, under phosphate limitation, deficiency of TagO precludes the synthesis of teichuronic acid, which is normally induced under these conditions. The regulatory region of tagO, containing two partly overlapping sigma(A)-controlled promoters, is similar to that of sigA, the gene encoding the major sigma factor responsible for growth. Here, the authors discuss the possibility that TagO may represent a pivotal element in the multi-enzyme complexes responsible for the synthesis of anionic cell-wall polymers, and that it may play one of the key roles in balanced cell growth.
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Affiliation(s)
- Blazenka Soldo
- Institut de Génétique et de Biologie Microbiennes, Université de Lausanne, Rue César-Roux 19, CH-1005 Lausanne, Switzerland1
| | - Vladimir Lazarevic
- Institut de Génétique et de Biologie Microbiennes, Université de Lausanne, Rue César-Roux 19, CH-1005 Lausanne, Switzerland1
| | - Dimitri Karamata
- Institut de Génétique et de Biologie Microbiennes, Université de Lausanne, Rue César-Roux 19, CH-1005 Lausanne, Switzerland1
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49
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Abstract
Staphylococcus aureus is a major pathogen both within hospitals and in the community. Methicillin, a beta-lactam antibiotic, acts by inhibiting penicillin-binding proteins (PBPs) that are involved in the synthesis of peptidoglycan, an essential mesh-like polymer that surrounds the cell. S. aureus can become resistant to methicillin and other beta-lactam antibiotics through the expression of a foreign PBP, PBP2a, that is resistant to the action of methicillin but which can perform the functions of the host PBPs. Methicillin-resistant S. aureus isolates are often resistant to other classes of antibiotics (through different mechanisms) making treatment options limited, and this has led to the search for new compounds active against these strains. An understanding of the mechanism of methicillin resistance has led to the discovery of accessory factors that influence the level and nature of methicillin resistance. Accessory factors, such as Fem factors, provide possible new targets, while compounds that modulate methicillin resistance such as epicatechin gallate, derived from green tea, and corilagin, provide possible lead compounds for development of inhibitors.
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50
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Shimizu M, Shiota S, Mizushima T, Ito H, Hatano T, Yoshida T, Tsuchiya T. Marked potentiation of activity of beta-lactams against methicillin-resistant Staphylococcus aureus by corilagin. Antimicrob Agents Chemother 2001; 45:3198-201. [PMID: 11600378 PMCID: PMC90804 DOI: 10.1128/aac.45.11.3198-3201.2001] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2000] [Accepted: 07/16/2001] [Indexed: 11/20/2022] Open
Abstract
We found that an extract of Arctostaphylos uva-ursi markedly reduced the MICs of beta-lactam antibiotics, such as oxacillin and cefmetazole, against methicillin-resistant Staphylococcus aureus. We isolated the effective compound and identified it as corilagin. Corilagin reduced the MICs of various beta-lactams by 100- to 2,000-fold but not the MICs of other antimicrobial agents tested. The effect of corilagin and oxacillin was synergistic. Corilagin showed a bactericidal action when added to the growth medium in combination with oxacillin.
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Affiliation(s)
- M Shimizu
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama, 700-8530, Japan
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