1
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Hsu TW, Fang JM. Advances and prospects of analytic methods for bacterial transglycosylation and inhibitor discovery. Analyst 2024; 149:2204-2222. [PMID: 38517346 DOI: 10.1039/d3an01968c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
The cell wall is essential for bacteria to maintain structural rigidity and withstand external osmotic pressure. In bacteria, the cell wall is composed of peptidoglycan. Lipid II is the basic unit for constructing highly cross-linked peptidoglycan scaffolds. Transglycosylase (TGase) is the initiating enzyme in peptidoglycan synthesis that catalyzes the ligation of lipid II moieties into repeating GlcNAc-MurNAc polysaccharides, followed by transpeptidation to generate cross-linked structures. In addition to the transglycosylases in the class-A penicillin-binding proteins (aPBPs), SEDS (shape, elongation, division and sporulation) proteins are also present in most bacteria and play vital roles in cell wall renewal, elongation, and division. In this review, we focus on the latest analytical methods including the use of radioactive labeling, gel electrophoresis, mass spectrometry, fluorescence labeling, probing undecaprenyl pyrophosphate, fluorescence anisotropy, ligand-binding-induced tryptophan fluorescence quenching, and surface plasmon resonance to evaluate TGase activity in cell wall formation. This review also covers the discovery of TGase inhibitors as potential antibacterial agents. We hope that this review will give readers a better understanding of the chemistry and basic research for the development of novel antibiotics.
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Affiliation(s)
- Tse-Wei Hsu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
| | - Jim-Min Fang
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
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2
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Gómez-Arrebola C, Hernandez SB, Culp EJ, Wright GD, Solano C, Cava F, Lasa I. Staphylococcus aureus susceptibility to complestatin and corbomycin depends on the VraSR two-component system. Microbiol Spectr 2023; 11:e0037023. [PMID: 37646518 PMCID: PMC10581084 DOI: 10.1128/spectrum.00370-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 06/30/2023] [Indexed: 09/01/2023] Open
Abstract
The overuse of antibiotics in humans and livestock has driven the emergence and spread of antimicrobial resistance and has therefore prompted research on the discovery of novel antibiotics. Complestatin (Cm) and corbomycin (Cb) are glycopeptide antibiotics with an unprecedented mechanism of action that is active even against methicillin-resistant and daptomycin-resistant Staphylococcus aureus. They bind to peptidoglycan and block the activity of peptidoglycan hydrolases required for remodeling the cell wall during growth. Bacterial signaling through two-component transduction systems (TCSs) has been associated with the development of S. aureus antimicrobial resistance. However, the role of TCSs in S. aureus susceptibility to Cm and Cb has not been previously addressed. In this study, we determined that, among all 16 S. aureus TCSs, VraSR is the only one controlling the susceptibility to Cm and Cb. Deletion of vraSR increased bacterial susceptibility to both antibiotics. Epistasis analysis with members of the vraSR regulon revealed that deletion of spdC, which encodes a membrane protein that scaffolds SagB for cleavage of peptidoglycan strands to achieve physiological length, in the vraSR mutant restored Cm and Cb susceptibility to wild-type levels. Moreover, deletion of either spdC or sagB in the wild-type strain increased resistance to both antibiotics. Further analyses revealed a significant rise in the relative amount of peptidoglycan and its total degree of cross-linkage in ΔspdC and ΔsagB mutants compared to the wild-type strain, suggesting that these changes in the cell wall provide resistance to the damaging effect of Cm and Cb. IMPORTANCE Although Staphylococcus aureus is a common colonizer of the skin and digestive tract of humans and many animals, it is also a versatile pathogen responsible for causing a wide variety and number of infections. Treatment of these infections requires the bacteria to be constantly exposed to antibiotic treatment, which facilitates the selection of antibiotic-resistant strains. The development of new antibiotics is, therefore, urgently needed. In this paper, we investigated the role of the sensory system of S. aureus in susceptibility to two new antibiotics: corbomycin and complestatin. The results shed light on the cell-wall synthesis processes that are affected by the presence of the antibiotic and the sensory system responsible for coordinating their activity.
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Affiliation(s)
- Carmen Gómez-Arrebola
- Laboratory of Microbial Pathogenesis, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
| | - Sara B. Hernandez
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Elizabeth J. Culp
- Department of Biochemistry and Biomedical Sciences, M. G. DeGroote Institute for Infectious Disease Research, David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, Ontario, Canada
| | - Gerard D. Wright
- Department of Biochemistry and Biomedical Sciences, M. G. DeGroote Institute for Infectious Disease Research, David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, Ontario, Canada
| | - Cristina Solano
- Laboratory of Microbial Pathogenesis, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
| | - Felipe Cava
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Iñigo Lasa
- Laboratory of Microbial Pathogenesis, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain
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3
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Nygaard R, Graham CLB, Belcher Dufrisne M, Colburn JD, Pepe J, Hydorn MA, Corradi S, Brown CM, Ashraf KU, Vickery ON, Briggs NS, Deering JJ, Kloss B, Botta B, Clarke OB, Columbus L, Dworkin J, Stansfeld PJ, Roper DI, Mancia F. Structural basis of peptidoglycan synthesis by E. coli RodA-PBP2 complex. Nat Commun 2023; 14:5151. [PMID: 37620344 PMCID: PMC10449877 DOI: 10.1038/s41467-023-40483-8] [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: 11/11/2022] [Accepted: 07/31/2023] [Indexed: 08/26/2023] Open
Abstract
Peptidoglycan (PG) is an essential structural component of the bacterial cell wall that is synthetized during cell division and elongation. PG forms an extracellular polymer crucial for cellular viability, the synthesis of which is the target of many antibiotics. PG assembly requires a glycosyltransferase (GT) to generate a glycan polymer using a Lipid II substrate, which is then crosslinked to the existing PG via a transpeptidase (TP) reaction. A Shape, Elongation, Division and Sporulation (SEDS) GT enzyme and a Class B Penicillin Binding Protein (PBP) form the core of the multi-protein complex required for PG assembly. Here we used single particle cryo-electron microscopy to determine the structure of a cell elongation-specific E. coli RodA-PBP2 complex. We combine this information with biochemical, genetic, spectroscopic, and computational analyses to identify the Lipid II binding sites and propose a mechanism for Lipid II polymerization. Our data suggest a hypothesis for the movement of the glycan strand from the Lipid II polymerization site of RodA towards the TP site of PBP2, functionally linking these two central enzymatic activities required for cell wall peptidoglycan biosynthesis.
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Affiliation(s)
- Rie Nygaard
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Chris L B Graham
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Meagan Belcher Dufrisne
- Department of Chemistry and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22904, USA
| | - Jonathan D Colburn
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Joseph Pepe
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Molly A Hydorn
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Silvia Corradi
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Faculty of Pharmacy and Medicine, Sapienza University of Rome, Rome, Italy
| | - Chelsea M Brown
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Khuram U Ashraf
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Owen N Vickery
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Nicholas S Briggs
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - John J Deering
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Brian Kloss
- New York Consortium on Membrane Protein Structure, New York Structural Biology Center, 89 Convent Avenue, New York, NY, 10027, USA
| | - Bruno Botta
- Faculty of Pharmacy and Medicine, Sapienza University of Rome, Rome, Italy
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Linda Columbus
- Department of Chemistry and Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22904, USA.
| | - Jonathan Dworkin
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA.
| | - Phillip J Stansfeld
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - David I Roper
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY, 10032, USA.
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4
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Goossens K, Neves RP, Fernandes PA, De Winter H. A Computational and Modeling Study of the Reaction Mechanism of Staphylococcus aureus Monoglycosyltransferase Reveals New Insights on the GT51 Family of Enzymes. J Chem Inf Model 2020; 60:5513-5528. [PMID: 32786224 DOI: 10.1021/acs.jcim.0c00377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Bacterial glycosyltransferases of the GT51 family are key enzymes in bacterial cell wall synthesis. Inhibiting cell wall synthesis is a very effective approach for development of antibiotics, as this can lead to either bacteriostatic or bactericidal effects. Even though the existence of this family has been known for over 50 years, only one potent inhibitor exists, which is an analog of the lipid IV product and derived from a natural product. Drug development focused on bacterial transglycosylase has been hampered due to little being know about its structure and reaction mechanism. In this study, Staphylococcus aureus monoglycosyltransferase was investigated at an atomistic level using computational methods. Classical molecular dynamics simulations were used to reveal information about the large-scale dynamics of the enzyme-substrate complex and the importance of magnesium in structure and function of the protein, while mixed mode quantum mechanics/molecular mechanics calculations unveiled a novel hypothesis for the reaction mechanism. From these results, we present a new model for the binding mode of lipid II and the reaction mechanism of the GT51 glycosyltransferases. A metal-bound hydroxide catalyzed reaction mechanism yields an estimated free energy barrier of 16.1 ± 1.0 kcal/mol, which is in line with experimental values. The importance of divalent cations is also further discussed. These findings could significantly aid targeted drug design, particularly the efficient development of transition state analogues as potential inhibitors for the GT51 glycosyltransferases.
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Affiliation(s)
- Kenneth Goossens
- Department of Pharmaceutical Sciences, Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Rui Pp Neves
- LAQV@REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
| | - Pedro A Fernandes
- LAQV@REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
| | - Hans De Winter
- Department of Pharmaceutical Sciences, Laboratory of Medicinal Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
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Welsh MA, Schaefer K, Taguchi A, Kahne D, Walker S. Direction of Chain Growth and Substrate Preferences of Shape, Elongation, Division, and Sporulation-Family Peptidoglycan Glycosyltransferases. J Am Chem Soc 2019; 141:12994-12997. [PMID: 31386359 PMCID: PMC6738341 DOI: 10.1021/jacs.9b06358] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The bacterial cell wall is composed of peptidoglycan, and its biosynthesis is an established target for antibiotics. Peptidoglycan is assembled from a glycopeptide precursor, Lipid II, that is polymerized by peptidoglycan glycosyltransferases into glycan strands that are subsequently cross-linked to form the mature cell wall. For decades bacteria were thought to contain only one family of enzymes that polymerize Lipid II, but recently, the ubiquitous Shape, Elongation, Division, and Sporulation (SEDS)-family proteins RodA and FtsW were shown to be peptidoglycan polymerases. Because RodA and FtsW are essential in nearly all bacteria, these enzymes are promising targets for new antibiotics. However, almost nothing is known about the mechanisms of these polymerases. Here, we report that SEDS proteins synthesize peptidoglycan by adding new Lipid II monomers to the reducing end of the growing glycan chain. Using substrates that can only react at the reducing end, we also show that the glycosyl donor and acceptor in the polymerization reaction have distinct lipid requirements. These findings provide the first fundamental insights into the mechanism of SEDS-family polymerases and lay the groundwork for future biochemical and structural studies.
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Affiliation(s)
- Michael A. Welsh
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Kaitlin Schaefer
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Atsushi Taguchi
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Suzanne Walker
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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6
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Abstract
Dating back to the 1960s, initial studies on the staphylococcal cell wall were driven by the need to clarify the mode of action of the first antibiotics and the resistance mechanisms developed by the bacteria. During the following decades, the elucidation of the biosynthetic path and primary composition of staphylococcal cell walls was propelled by advances in microbial cell biology, specifically, the introduction of high-resolution analytical techniques and molecular genetic approaches. The field of staphylococcal cell wall gradually gained its own significance as the complexity of its chemical structure and involvement in numerous cellular processes became evident, namely its versatile role in host interactions, coordination of cell division and environmental stress signaling.This chapter includes an updated description of the anatomy of staphylococcal cell walls, paying particular attention to information from the last decade, under four headings: high-resolution analysis of the Staphylococcus aureus peptidoglycan; variations in peptidoglycan composition; genetic determinants and enzymes in cell wall synthesis; and complex functions of cell walls. The latest contributions to a more precise picture of the staphylococcal cell envelope were possible due to recently developed state-of-the-art microscopy and spectroscopy techniques and to a wide combination of -omics approaches, that are allowing to obtain a more integrative view of this highly dynamic structure.
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Affiliation(s)
- Rita Sobral
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
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Inactivation of the Monofunctional Peptidoglycan Glycosyltransferase SgtB Allows Staphylococcus aureus To Survive in the Absence of Lipoteichoic Acid. J Bacteriol 2018; 201:JB.00574-18. [PMID: 30322854 PMCID: PMC6287468 DOI: 10.1128/jb.00574-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 10/08/2018] [Indexed: 12/29/2022] Open
Abstract
The bacterial cell wall acts as a primary defense against environmental insults such as changes in osmolarity. It is also a vulnerable structure, as defects in its synthesis can lead to growth arrest or cell death. The important human pathogen Staphylococcus aureus has a typical Gram-positive cell wall, which consists of peptidoglycan and the anionic polymers LTA and wall teichoic acid. Several clinically relevant antibiotics inhibit the synthesis of peptidoglycan; therefore, it and teichoic acids are considered attractive targets for the development of new antimicrobials. We show that LTA is required for efficient peptidoglycan cross-linking in S. aureus and inactivation of a peptidoglycan glycosyltransferase can partially rescue this defect, together revealing an intimate link between peptidoglycan and LTA synthesis. The cell wall of Staphylococcus aureus is composed of peptidoglycan and the anionic polymers lipoteichoic acid (LTA) and wall teichoic acid. LTA is required for growth and normal cell morphology in S. aureus. Strains lacking LTA are usually viable only when grown under osmotically stabilizing conditions or after the acquisition of compensatory mutations. LTA-negative suppressor strains with inactivating mutations in gdpP, which resulted in increased intracellular c-di-AMP levels, were described previously. Here, we sought to identify factors other than c-di-AMP that allow S. aureus to survive without LTA. LTA-negative strains able to grow in unsupplemented medium were obtained and found to contain mutations in sgtB, mazE, clpX, or vraT. The growth improvement through mutations in mazE and sgtB was confirmed by complementation analysis. We also showed that an S. aureussgtB transposon mutant, with the monofunctional peptidoglycan glycosyltransferase SgtB inactivated, displayed a 4-fold increase in the MIC of oxacillin, suggesting that alterations in the peptidoglycan structure could help bacteria compensate for the lack of LTA. Muropeptide analysis of peptidoglycans isolated from a wild-type strain and sgtB mutant strain did not reveal any sizable alterations in the peptidoglycan structure. In contrast, the peptidoglycan isolated from an LTA-negative ltaS mutant strain showed a significant reduction in the fraction of highly cross-linked peptidoglycan, which was partially rescued in the sgtB ltaS double mutant suppressor strain. Taken together, these data point toward an important function of LTA in cell wall integrity through its necessity for proper peptidoglycan assembly. IMPORTANCE The bacterial cell wall acts as a primary defense against environmental insults such as changes in osmolarity. It is also a vulnerable structure, as defects in its synthesis can lead to growth arrest or cell death. The important human pathogen Staphylococcus aureus has a typical Gram-positive cell wall, which consists of peptidoglycan and the anionic polymers LTA and wall teichoic acid. Several clinically relevant antibiotics inhibit the synthesis of peptidoglycan; therefore, it and teichoic acids are considered attractive targets for the development of new antimicrobials. We show that LTA is required for efficient peptidoglycan cross-linking in S. aureus and inactivation of a peptidoglycan glycosyltransferase can partially rescue this defect, together revealing an intimate link between peptidoglycan and LTA synthesis.
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8
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Dahmane I, Montagner C, Matagne A, Dumbre S, Herdewijn P, Terrak M. Peptidoglycan glycosyltransferase-ligand binding assay based on tryptophan fluorescence quenching. Biochimie 2018; 152:1-5. [PMID: 29909047 DOI: 10.1016/j.biochi.2018.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/13/2018] [Indexed: 11/28/2022]
Abstract
Peptidoglycan glycosyltransferases (GTase) of family 51 are essential enzymes for the synthesis of the glycan chains of the bacterial cell wall. They are considered potential antibacterial target, but discovery of inhibitors was hampered so far by the lack of efficient and affordable screening assay. Here we used Staphylococcus aureus MtgA to introduce a single tryptophan reporter residue in selected positions flanking the substrates binding cavity of the protein. We selected a mutant (Y181W) that shows strong fluorescence quenching in the presence of moenomycin A and two lipid II analogs inhibitors. The assay provides a simple method to study GTase-ligand interactions and can be used as primary high throughput screening of GTase inhibitors without the need for lipid II substrate or reporter ligands.
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Affiliation(s)
- Ismahene Dahmane
- Centre d'Ingénierie des Protéines-InBioS, University of Liège, B6a, Quartier Agora, Allée du six Août 11, 4000, Liège 1, Belgium
| | - Caroline Montagner
- Centre d'Ingénierie des Protéines-InBioS, University of Liège, B6a, Quartier Agora, Allée du six Août 11, 4000, Liège 1, Belgium
| | - André Matagne
- Centre d'Ingénierie des Protéines-InBioS, University of Liège, B6a, Quartier Agora, Allée du six Août 11, 4000, Liège 1, Belgium
| | - Shrinivas Dumbre
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, University of Leuven, Belgium
| | - Piet Herdewijn
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, University of Leuven, Belgium
| | - Mohammed Terrak
- Centre d'Ingénierie des Protéines-InBioS, University of Liège, B6a, Quartier Agora, Allée du six Août 11, 4000, Liège 1, Belgium.
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9
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Ngo M, Suits MDL. Methods for Determining Glycosyltransferase Kinetics. Methods Mol Biol 2017; 1588:59-70. [PMID: 28417361 DOI: 10.1007/978-1-4939-6899-2_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Glycosyltransferases are a class of biosynthetic enzymes that transfer individual activated monosaccharide units to specific acceptors. Colorimetric assays using the detection of released products such as para-nitrophenol and coupled assays for inorganic phosphate detection allow for convenient and quantifiable kinetic characterization. These techniques may be applied to determine the enzymatic activity of glycosyltransferases by indirectly measuring the transfer of nucleotide-activated donor carbohydrate units to various cognate acceptor molecules. In addition to an overview of these methods, the protocol for quantifying the glycosyltransferase activity used for the characterization of penicillin-binding proteins (PBPs) involving the transfer of lipid II to form elongated murein chains during bacterial cell wall synthesis is described herein.
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Affiliation(s)
- Maria Ngo
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON, Canada, N2L 3C5
| | - Michael D L Suits
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON, Canada, N2L 3C5.
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10
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Glycosyltransferases and Transpeptidases/Penicillin-Binding Proteins: Valuable Targets for New Antibacterials. Antibiotics (Basel) 2016; 5:antibiotics5010012. [PMID: 27025527 PMCID: PMC4810414 DOI: 10.3390/antibiotics5010012] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 01/27/2016] [Accepted: 02/03/2016] [Indexed: 12/29/2022] Open
Abstract
Peptidoglycan (PG) is an essential macromolecular sacculus surrounding most bacteria. It is assembled by the glycosyltransferase (GT) and transpeptidase (TP) activities of multimodular penicillin-binding proteins (PBPs) within multiprotein complex machineries. Both activities are essential for the synthesis of a functional stress-bearing PG shell. Although good progress has been made in terms of the functional and structural understanding of GT, finding a clinically useful antibiotic against them has been challenging until now. In contrast, the TP/PBP module has been successfully targeted by β-lactam derivatives, but the extensive use of these antibiotics has selected resistant bacterial strains that employ a wide variety of mechanisms to escape the lethal action of these antibiotics. In addition to traditional β-lactams, other classes of molecules (non-β-lactams) that inhibit PBPs are now emerging, opening new perspectives for tackling the resistance problem while taking advantage of these valuable targets, for which a wealth of structural and functional knowledge has been accumulated. The overall evidence shows that PBPs are part of multiprotein machineries whose activities are modulated by cofactors. Perturbation of these systems could lead to lethal effects. Developing screening strategies to take advantage of these mechanisms could lead to new inhibitors of PG assembly. In this paper, we present a general background on the GTs and TPs/PBPs, a survey of recent issues of bacterial resistance and a review of recent works describing new inhibitors of these enzymes.
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11
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Lee W, Schaefer K, Qiao Y, Srisuknimit V, Steinmetz H, Müller R, Kahne D, Walker S. The Mechanism of Action of Lysobactin. J Am Chem Soc 2015; 138:100-3. [PMID: 26683668 DOI: 10.1021/jacs.5b11807] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Lysobactin, also known as katanosin B, is a potent antibiotic with in vivo efficacy against Staphylococcus aureus and Streptococcus pneumoniae. It was previously shown to inhibit peptidoglycan (PG) biosynthesis, but its molecular mechanism of action has not been established. Using enzyme inhibition assays, we show that lysobactin forms 1:1 complexes with Lipid I, Lipid II, and Lipid II(A)(WTA), substrates in the PG and wall teichoic acid (WTA) biosynthetic pathways. Therefore, lysobactin, like ramoplanin and teixobactin, recognizes the reducing end of lipid-linked cell wall precursors. We show that despite its ability to bind precursors from different pathways, lysobactin's cellular mechanism of killing is due exclusively to Lipid II binding, which causes septal defects and catastrophic cell envelope damage.
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Affiliation(s)
- Wonsik Lee
- Department of Microbiology and Immunology, Harvard Medical School , Boston, Massachusetts 02115, United States
| | - Kaitlin Schaefer
- Department of Microbiology and Immunology, Harvard Medical School , Boston, Massachusetts 02115, United States.,Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Yuan Qiao
- Department of Microbiology and Immunology, Harvard Medical School , Boston, Massachusetts 02115, United States.,Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Veerasak Srisuknimit
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Heinrich Steinmetz
- Department of Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), and Pharmaceutical Biotechnology, Saarland University , Campus E8.1, 66123 Saarbrücken, Germany
| | - Rolf Müller
- Department of Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), and Pharmaceutical Biotechnology, Saarland University , Campus E8.1, 66123 Saarbrücken, Germany
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Suzanne Walker
- Department of Microbiology and Immunology, Harvard Medical School , Boston, Massachusetts 02115, United States
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12
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Mesleh MF, Rajaratnam P, Conrad M, Chandrasekaran V, Liu CM, Pandya BA, Hwang YS, Rye PT, Muldoon C, Becker B, Zuegg J, Meutermans W, Moy TI. Targeting Bacterial Cell Wall Peptidoglycan Synthesis by Inhibition of Glycosyltransferase Activity. Chem Biol Drug Des 2015; 87:190-9. [PMID: 26358369 DOI: 10.1111/cbdd.12662] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 08/20/2015] [Accepted: 08/27/2015] [Indexed: 11/25/2022]
Abstract
Synthesis of bacterial cell wall peptidoglycan requires glycosyltransferase enzymes that transfer the disaccharide-peptide from lipid II onto the growing glycan chain. The polymerization of the glycan chain precedes cross-linking by penicillin-binding proteins and is essential for growth for key bacterial pathogens. As such, bacterial cell wall glycosyltransferases are an attractive target for antibiotic drug discovery. However, significant challenges to the development of inhibitors for these targets include the development of suitable assays and chemical matter that is suited to the nature of the binding site. We developed glycosyltransferase enzymatic activity and binding assays using the natural products moenomycin and vancomycin as model inhibitors. In addition, we designed a library of disaccharide compounds based on the minimum moenomycin fragment with peptidoglycan glycosyltransferase inhibitory activity and based on a more drug-like and synthetically versatile disaccharide building block. A subset of these disaccharide compounds bound and inhibited the glycosyltransferase enzymes, and these compounds could serve as chemical entry points for antibiotic development.
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Affiliation(s)
- Michael F Mesleh
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Premraj Rajaratnam
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Mary Conrad
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Vasu Chandrasekaran
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Christopher M Liu
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Bhaumik A Pandya
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - You Seok Hwang
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
| | - Peter T Rye
- Agilent Technologies, Inc., 11 Audubon Road, Wakefield, MA, 01880, USA
| | - Craig Muldoon
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Bernd Becker
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Johannes Zuegg
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Wim Meutermans
- Alchemia Limited, 3 Hi-Tech Court, Eight Mile Plains, Brisbane Technology Park, Qld, 4113, Australia
| | - Terence I Moy
- Cubist Pharmaceuticals, a wholly-owned subsidiary of Merck & Co. Inc., 65 Hayden Avenue, Lexington, MA, 02421, USA
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13
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Blanchaert B, Wyseure T, Breukink E, Adams E, Declerck P, Van Schepdael A. Development of a liquid chromatography/mass spectrometry assay for the bacterial transglycosylation reaction through measurement of Lipid II. Electrophoresis 2015; 36:2841-2849. [DOI: 10.1002/elps.201500201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Bart Blanchaert
- Department of Pharmaceutical and Pharmacological sciences, Pharmaceutical analysis; KU Leuven - University of Leuven; Leuven Belgium
| | - Tine Wyseure
- Department of Pharmaceutical and Pharmacological sciences, Therapeutic and Diagnostic Antibodies; KU Leuven - University of Leuven; Leuven Belgium
| | - Eefjan Breukink
- Department of Biochemistry of Membranes, Bijvoet Center for Biomolecular Research; University of Utrecht; Utrecht The Netherlands
| | - Erwin Adams
- Department of Pharmaceutical and Pharmacological sciences, Pharmaceutical analysis; KU Leuven - University of Leuven; Leuven Belgium
| | - Paul Declerck
- Department of Pharmaceutical and Pharmacological sciences, Therapeutic and Diagnostic Antibodies; KU Leuven - University of Leuven; Leuven Belgium
| | - Ann Van Schepdael
- Department of Pharmaceutical and Pharmacological sciences, Pharmaceutical analysis; KU Leuven - University of Leuven; Leuven Belgium
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14
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Egan AJF, Biboy J, van't Veer I, Breukink E, Vollmer W. Activities and regulation of peptidoglycan synthases. Philos Trans R Soc Lond B Biol Sci 2015; 370:20150031. [PMID: 26370943 PMCID: PMC4632607 DOI: 10.1098/rstb.2015.0031] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2015] [Indexed: 12/22/2022] Open
Abstract
Peptidoglycan (PG) is an essential component in the cell wall of nearly all bacteria, forming a continuous, mesh-like structure, called the sacculus, around the cytoplasmic membrane to protect the cell from bursting by its turgor. Although PG synthases, the penicillin-binding proteins (PBPs), have been studied for 70 years, useful in vitro assays for measuring their activities were established only recently, and these provided the first insights into the regulation of these enzymes. Here, we review the current knowledge on the glycosyltransferase and transpeptidase activities of PG synthases. We provide new data showing that the bifunctional PBP1A and PBP1B from Escherichia coli are active upon reconstitution into the membrane environment of proteoliposomes, and that these enzymes also exhibit DD-carboxypeptidase activity in certain conditions. Both novel features are relevant for their functioning within the cell. We also review recent data on the impact of protein-protein interactions and other factors on the activities of PBPs. As an example, we demonstrate a synergistic effect of multiple protein-protein interactions on the glycosyltransferase activity of PBP1B, by its cognate lipoprotein activator LpoB and the essential cell division protein FtsN.
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Affiliation(s)
- Alexander J F Egan
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
| | - Inge van't Veer
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, University of Utrecht, Padualaan 8, 3584 Utrecht, The Netherlands
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, University of Utrecht, Padualaan 8, 3584 Utrecht, The Netherlands
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
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15
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Abstract
Gram-positive organisms, including the pathogens Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis, have dynamic cell envelopes that mediate interactions with the environment and serve as the first line of defense against toxic molecules. Major components of the cell envelope include peptidoglycan (PG), which is a well-established target for antibiotics, teichoic acids (TAs), capsular polysaccharides (CPS), surface proteins, and phospholipids. These components can undergo modification to promote pathogenesis, decrease susceptibility to antibiotics and host immune defenses, and enhance survival in hostile environments. This chapter will cover the structure, biosynthesis, and important functions of major cell envelope components in gram-positive bacteria. Possible targets for new antimicrobials will be noted.
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16
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Bury D, Dahmane I, Derouaux A, Dumbre S, Herdewijn P, Matagne A, Breukink E, Mueller-Seitz E, Petz M, Terrak M. Positive cooperativity between acceptor and donor sites of the peptidoglycan glycosyltransferase. Biochem Pharmacol 2014; 93:141-50. [PMID: 25462814 DOI: 10.1016/j.bcp.2014.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 11/07/2014] [Accepted: 11/07/2014] [Indexed: 12/01/2022]
Abstract
The glycosyltransferases of family 51 (GT51) catalyze the polymerization of lipid II to form linear glycan chains, which, after cross linking by the transpeptidases, form the net-like peptidoglycan macromolecule. The essential function of the GT makes it an attractive antimicrobial target; therefore a better understanding of its function and its mechanism of interaction with substrates could help in the design and the development of new antibiotics. In this work, we have used a surface plasmon resonance Biacore(®) biosensor, based on an amine derivative of moenomycin A immobilized on a sensor chip surface, to investigate the mechanism of binding of substrate analogous inhibitors to the GT. Addition of increasing concentrations of moenomycin A to the Staphylococcus aureus MtgA led to reduced binding of the protein to the sensor chip as expected. Remarkably, in the presence of low concentrations of the most active disaccharide inhibitors, binding of MtgA to immobilized moenomycin A was found to increase; in contrast competition with moenomycin A occurred only at high concentrations. This finding suggests that at low concentrations, the lipid II analogs bind to the acceptor site and induce a cooperative binding of moenomycin A to the donor site. Our results constitute the first indication of the existence of a positive cooperativity between the acceptor and the donor sites of peptidoglycan GTs. In addition, our study indicates that a modification of two residues (L119N and F120S) within the hydrophobic region of MtgA can yield monodisperse forms of the protein with apparently no change in its secondary structure content, but this is at the expense of the enzyme function.
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Affiliation(s)
- Daniel Bury
- Department of Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaussstr. 20, 42119 Wuppertal, Germany.
| | - Ismahene Dahmane
- Centre d'Ingénierie des Protéines, Université de Liège, Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
| | - Adeline Derouaux
- Centre d'Ingénierie des Protéines, Université de Liège, Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
| | - Shrinivas Dumbre
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - Piet Herdewijn
- Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, University of Leuven, Leuven, Belgium
| | - André Matagne
- Centre d'Ingénierie des Protéines, Université de Liège, Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Erika Mueller-Seitz
- Department of Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaussstr. 20, 42119 Wuppertal, Germany
| | - Michael Petz
- Department of Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaussstr. 20, 42119 Wuppertal, Germany
| | - Mohammed Terrak
- Centre d'Ingénierie des Protéines, Université de Liège, Allée de la Chimie, B6a, B-4000, Sart Tilman, Liège, Belgium.
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17
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Qiao Y, Lebar MD, Schirner K, Schaefer K, Tsukamoto H, Kahne D, Walker S. Detection of lipid-linked peptidoglycan precursors by exploiting an unexpected transpeptidase reaction. J Am Chem Soc 2014; 136:14678-81. [PMID: 25291014 PMCID: PMC4210121 DOI: 10.1021/ja508147s] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
![]()
Penicillin-binding
proteins (PBPs) are involved in the synthesis
and remodeling of bacterial peptidoglycan (PG). Staphylococcus
aureus expresses four PBPs. Genetic studies in S.
aureus have implicated PBP4 in the formation of highly cross-linked
PG, but biochemical studies have not reached a consensus on its primary
enzymatic activity. Using synthetic Lipid II, we show here that PBP4
preferentially acts as a transpeptidase (TP) in vitro. Moreover, it is the PBP primarily responsible for incorporating
exogenous d-amino acids into cellular PG, implying that it
also has TP activity in vivo. Notably, PBP4 efficiently
exchanges d-amino acids not only into PG polymers but also
into the PG monomers Lipid I and Lipid II. This is the first demonstration
that any TP domain of a PBP can activate the PG monomer building blocks.
Exploiting the promiscuous TP activity of PBP4, we developed a simple,
highly sensitive assay to detect cellular pools of lipid-linked PG
precursors, which are of notoriously low abundance. This method, which
addresses a longstanding problem, is useful for assessing how genetic
and pharmacological perturbations affect precursor levels, and may
facilitate studies to elucidate antibiotic mechanism of action.
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Affiliation(s)
- Yuan Qiao
- Chemical Biology Program, Harvard University , Cambridge, Massachusetts 02138, United States
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18
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Braddick D, Sandhu S, Roper DI, Chappell MJ, Bugg TDH. Observation of the time-course for peptidoglycan lipid intermediate II polymerization by Staphylococcus aureus monofunctional transglycosylase. MICROBIOLOGY-SGM 2014; 160:1628-1636. [PMID: 24858082 DOI: 10.1099/mic.0.079442-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The polymerization of lipid intermediate II by the transglycosylase activity of penicillin-binding proteins (PBPs) represents an important target for antibacterial action, but limited methods are available for quantitative assay of this reaction, or screening potential inhibitors. A new labelling method for lipid II polymerization products using Sanger's reagent (fluoro-2,4-dinitrobenzene), followed by gel permeation HPLC analysis, has permitted the observation of intermediate polymerization products for Staphylococcus aureus monofunctional transglycosylase MGT. Peak formation is inhibited by 6 µM ramoplanin or enduracidin. Characterization by mass spectrometry indicates the formation of tetrasaccharide and octasaccharide intermediates, but not a hexasaccharide intermediate, suggesting a dimerization of a lipid-linked tetrasaccharide. Numerical modelling of the time-course data supports a kinetic model involving addition to lipid-linked tetrasaccharide of either lipid II or lipid-linked tetrasaccharide. Observation of free octasaccharide suggests that hydrolysis of the undecaprenyl diphosphate lipid carrier occurs at this stage in peptidoglycan transglycosylation.
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Affiliation(s)
- Darren Braddick
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Sandeep Sandhu
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - David I Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | - Timothy D H Bugg
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
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19
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Galley NF, O'Reilly AM, Roper DI. Prospects for novel inhibitors of peptidoglycan transglycosylases. Bioorg Chem 2014; 55:16-26. [PMID: 24924926 PMCID: PMC4126109 DOI: 10.1016/j.bioorg.2014.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/12/2014] [Accepted: 05/12/2014] [Indexed: 01/07/2023]
Abstract
We examine key aspects of transglycosylase inhibitor design. Low to high throughput assays suitable for transglycosylase drug discovery. Existing chemical start points for transglycosylase active site targeting.
The lack of novel antimicrobial drugs under development coupled with the increasing occurrence of resistance to existing antibiotics by community and hospital acquired infections is of grave concern. The targeting of biosynthesis of the peptidoglycan component of the bacterial cell wall has proven to be clinically valuable but relatively little therapeutic development has been directed towards the transglycosylase step of this process. Advances towards the isolation of new antimicrobials that target transglycosylase activity will rely on the development of the enzymological tools required to identify and characterise novel inhibitors of these enzymes. Therefore, in this article, we review the assay methods developed for transglycosylases and review recent novel chemical inhibitors discovered in relation to both the lipidic substrates and natural product inhibitors of the transglycosylase step.
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Affiliation(s)
- Nicola F Galley
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Amy M O'Reilly
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - David I Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
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20
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Rebets Y, Lupoli T, Qiao Y, Schirner K, Villet R, Hooper D, Kahne D, Walker S. Moenomycin resistance mutations in Staphylococcus aureus reduce peptidoglycan chain length and cause aberrant cell division. ACS Chem Biol 2014; 9:459-67. [PMID: 24255971 DOI: 10.1021/cb4006744] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Staphylococcus aureus is a Gram-positive pathogen with an unusual mode of cell division in that it divides in orthogonal rather than parallel planes. Through selection using moenomycin, an antibiotic proposed to target peptidoglycan glycosyltransferases (PGTs), we have generated resistant mutants containing a single point mutation in the active site of the PGT domain of an essential peptidoglycan (PG) biosynthetic enzyme, PBP2. Using cell free polymerization assays, we show that this mutation alters PGT activity so that much shorter PG chains are made. The same mutation in another S. aureus PGT, SgtB, has a similar effect on glycan chain length. Moenomycin-resistant S. aureus strains containing mutated PGTs that make only short glycan polymers display major cell division defects, implicating PG chain length in determining bacterial cell morphology and division site placement.
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Affiliation(s)
- Yuriy Rebets
- Department
of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Tania Lupoli
- Department
of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Yuan Qiao
- Department
of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Kathrin Schirner
- Department
of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Regis Villet
- Division
of Infectious Diseases and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - David Hooper
- Division
of Infectious Diseases and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Daniel Kahne
- Department
of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Suzanne Walker
- Department
of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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21
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Huang SH, Wu WS, Huang LY, Huang WF, Fu WC, Chen PT, Fang JM, Cheng WC, Cheng TJR, Wong CH. New continuous fluorometric assay for bacterial transglycosylase using Förster resonance energy transfer. J Am Chem Soc 2013; 135:17078-89. [PMID: 24131464 DOI: 10.1021/ja407985m] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The emergence of antibiotic resistance has prompted scientists to search for new antibiotics. Transglycosylase (TGase) is an attractive target for new antibiotic discovery due to its location on the outer membrane of bacteria and its essential role in peptidoglycan synthesis. Though there have been a few molecules identified as TGase inhibitors in the past thirty years, none of them have been developed into antibiotics for humans. The slow pace of development is perhaps due to the lack of continuous, quantitative, and high-throughput assay available for the enzyme. Herein, we report a new continuous fluorescent assay based on Förster resonance energy transfer, using lipid II analogues with a dimethylamino-azobenzenesulfonyl quencher in the lipid chain and a coumarin fluorophore in the peptide chain. During the process of transglycosylation, the quencher-appended polyprenol is released and the fluorescence of coumarin can be detected. Using this system, the substrate specificity and affinity of lipid II analogues bearing various numbers and configurations of isoprene units were investigated. Moreover, the inhibition constants of moenomycin and two previously identified small molecules were also determined. In addition, a high-throughput screening using the new assay was conducted to identify potent TGase inhibitors from a 120,000 compound library. This new continuous fluorescent assay not only provides an efficient and convenient way to study TGase activities, but also enables the high-throughput screening of potential TGase inhibitors for antibiotic discovery.
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Affiliation(s)
- Shih-Hsien Huang
- Genomics Research Center, Academia Sinica , 128 Academia Road, Section 2, Nankang, Taipei, 115, Taiwan
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22
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Shih HW, Chang YF, Li WJ, Meng FC, Huang CY, Ma C, Cheng TJR, Wong CH, Cheng WC. Effect of the Peptide Moiety of Lipid II on Bacterial Transglycosylase. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201204038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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23
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Shih HW, Chang YF, Li WJ, Meng FC, Huang CY, Ma C, Cheng TJR, Wong CH, Cheng WC. Effect of the peptide moiety of Lipid II on bacterial transglycosylase. Angew Chem Int Ed Engl 2012; 51:10123-6. [PMID: 22952114 DOI: 10.1002/anie.201204038] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Hao-Wei Shih
- Genomics Research Center, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan
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24
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White CL, Gober JW. MreB: pilot or passenger of cell wall synthesis? Trends Microbiol 2012; 20:74-9. [DOI: 10.1016/j.tim.2011.11.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 11/07/2011] [Accepted: 11/10/2011] [Indexed: 01/08/2023]
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25
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Hao H, Cheng G, Dai M, Wu Q, Yuan Z. Inhibitors targeting on cell wall biosynthesis pathway of MRSA. MOLECULAR BIOSYSTEMS 2012; 8:2828-38. [DOI: 10.1039/c2mb25188d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Monofunctional transglycosylases are not essential for Staphylococcus aureus cell wall synthesis. J Bacteriol 2011; 193:2549-56. [PMID: 21441517 DOI: 10.1128/jb.01474-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The polymerization of peptidoglycan is the result of two types of enzymatic activities: transglycosylation, the formation of linear glycan chains, and transpeptidation, the formation of peptide cross-bridges between the glycan strands. Staphylococcus aureus has four penicillin binding proteins (PBP1 to PBP4) with transpeptidation activity, one of which, PBP2, is a bifunctional enzyme that is also capable of catalyzing transglycosylation reactions. Additionally, two monofunctional transglycosylases have been reported in S. aureus: MGT, which has been shown to have in vitro transglycosylase activity, and a second putative transglycosylase, SgtA, identified only by sequence analysis. We have now shown that purified SgtA has in vitro transglycosylase activity and that both MGT and SgtA are not essential in S. aureus. However, in the absence of PBP2 transglycosylase activity, MGT but not SgtA becomes essential for cell viability. This indicates that S. aureus cells require one transglycosylase for survival, either PBP2 or MGT, both of which can act as the sole synthetic transglycosylase for cell wall synthesis. We have also shown that both MGT and SgtA interact with PBP2 and other enzymes involved in cell wall synthesis in a bacterial two-hybrid assay, suggesting that these enzymes may work in collaboration as part of a larger, as-yet-uncharacterized cell wall-synthetic complex.
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27
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Derouaux A, Turk S, Olrichs NK, Gobec S, Breukink E, Amoroso A, Offant J, Bostock J, Mariner K, Chopra I, Vernet T, Zervosen A, Joris B, Frère JM, Nguyen-Distèche M, Terrak M. Small molecule inhibitors of peptidoglycan synthesis targeting the lipid II precursor. Biochem Pharmacol 2011; 81:1098-105. [PMID: 21356201 DOI: 10.1016/j.bcp.2011.02.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 02/10/2011] [Accepted: 02/14/2011] [Indexed: 11/19/2022]
Abstract
Bacterial peptidoglycan glycosyltransferases (GTs) of family 51 catalyze the polymerization of the lipid II precursor into linear peptidoglycan strands. This activity is essential to bacteria and represents a validated target for the development of new antibacterials. Application of structure-based virtual screening to the National Cancer Institute library using eHits program and the structure of the glycosyltransferase domain of the Staphylococcus aureus penicillin-binding protein 2 resulted in the identification of two small molecules analogues 5, a 2-[1-[(2-chlorophenyl)methyl]-2-methyl-5-methylsulfanylindol-3-yl]ethanamine and 5b, a 2-[1-[(3,4-dichlorophenyl)methyl]-2-methyl-5-methylsulfanylindol-3-yl]ethanamine that exhibit antibacterial activity against several Gram-positive bacteria but were less active on Gram-negative bacteria. The two compounds inhibit the activity of five GTs in the micromolar range. Investigation of the mechanism of action shows that the compounds specifically target peptidoglycan synthesis. Unexpectedly, despite the fact that the compounds were predicted to bind to the GT active site, compound 5b was found to interact with the lipid II substrate via the pyrophosphate motif. In addition, this compound showed a negatively charged phospholipid-dependent membrane depolarization and disruption activity. These small molecules are promising leads for the development of more active and specific compounds to target the essential GT step in cell wall synthesis.
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Affiliation(s)
- Adeline Derouaux
- Centre d'Ingénierie des Protéines, Université de Liège, Allée de la chimie, B6a, B-4000, Sart Tilman, Liège, Belgium
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28
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Macheboeuf P, Piuzzi M, Finet S, Bontems F, Pérez J, Dessen A, Vachette P. Solution X-ray scattering study of a full-length class A penicillin-binding protein. Biochem Biophys Res Commun 2011; 405:107-11. [PMID: 21216228 DOI: 10.1016/j.bbrc.2011.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 01/02/2011] [Indexed: 10/18/2022]
Abstract
Penicillin binding proteins (PBPs) catalyze essential steps in the biosynthesis of peptidoglycan, the main component of the bacterial cell wall. PBPs can harbor two catalytic domains, namely the glycosyltransferase (GT) and transpeptidase (TP) activities, the latter being the target for β-lactam antibiotics. Despite the availability of structural information regarding bi-functional PBPs, little is known regarding the interaction and flexibility between the TP and GT domains. Here, we describe the structural characterization in solution by small angle X-ray scattering (SAXS) of PBP1b, a bi-functional PBP from Streptococcus pneumoniae. The molecule is present in solution as an elongated monomer. Refinement of internal coordinates starting from a homology model yields models in which the two domains are in an extended conformation without any mutual contact compatible with the existence of restricted mobility.
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Affiliation(s)
- P Macheboeuf
- Institut de Biologie Structurale, Bacterial Pathogenesis Group, UMR 5075 (CEA, CNRS, University Joseph Fourier-Grenoble I), Grenoble, France.
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Gautam A, Vyas R, Tewari R. Peptidoglycan biosynthesis machinery: a rich source of drug targets. Crit Rev Biotechnol 2010; 31:295-336. [PMID: 21091161 DOI: 10.3109/07388551.2010.525498] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The range of antibiotic therapy for the control of bacterial infections is becoming increasingly limited because of the rapid rise in multidrug resistance in clinical bacterial isolates. A few diseases, such as tuberculosis, which were once thought to be under control, have re-emerged as serious health threats. These problems have resulted in intensified research to look for new inhibitors for bacterial pathogens. Of late, the peptidoglycan (PG) layer, the most important component of the bacterial cell wall has been the subject of drug targeting because, first, it is essential for the survivability of eubacteria and secondly, it is absent in humans. The last decade has seen tremendous inputs in deciphering the 3-D structures of the PG biosynthetic enzymes. Many inhibitors against these enzymes have been developed using virtual and high throughput screening techniques. This review discusses the mechanistic and structural properties of the PG biosynthetic enzymes and inhibitors developed in the last decade.
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Affiliation(s)
- Ankur Gautam
- Department of Biotechnology, Panjab University, Chandigarh, India
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Offant J, Terrak M, Derouaux A, Breukink E, Nguyen-Distèche M, Zapun A, Vernet T. Optimization of conditions for the glycosyltransferase activity of penicillin-binding protein 1a from Thermotoga maritima. FEBS J 2010; 277:4290-8. [DOI: 10.1111/j.1742-4658.2010.07817.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Kawai F, Clarke TB, Roper DI, Han GJ, Hwang KY, Unzai S, Obayashi E, Park SY, Tame JR. Crystal Structures of Penicillin-Binding Proteins 4 and 5 from Haemophilus influenzae. J Mol Biol 2010; 396:634-45. [DOI: 10.1016/j.jmb.2009.11.055] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 11/20/2009] [Accepted: 11/22/2009] [Indexed: 10/20/2022]
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Heaslet H, Shaw B, Mistry A, Miller AA. Characterization of the active site of S. aureus monofunctional glycosyltransferase (Mtg) by site-directed mutation and structural analysis of the protein complexed with moenomycin. J Struct Biol 2009; 167:129-35. [PMID: 19416756 DOI: 10.1016/j.jsb.2009.04.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Revised: 04/14/2009] [Accepted: 04/28/2009] [Indexed: 11/16/2022]
Abstract
Bacterial cell wall transglycosylases (TGs) and transpeptidases (TPs) are ideal drug targets due to their essentiality, accessibility and lack of mammalian homologs. Although antibacterial therapy using the beta-lactam family of TP inhibitors has been successful for decades, potent TG inhibitors which are suitable for development into antibiotics for human use have yet to be identified. We sought to further understand the molecular interactions required to inhibit bacterial transglycosylation by characterizing the active site of Staphylococcus aureus (Sa) monofunctional transglycosylase (Mtg). Ten mutants were tested for their ability to polymerize Lipid II and to crystallize in the presence of moenomycin. Five of six putative active site mutants (E100Q, D101N, Q136E, E156T, and Y176F) were found to be catalytically inactive whereas a F104Y mutation did not affect activity. Four mutants generated to enhance crystal formation (F143T, V154T, L157T, and F158T) also retained activity. Here we also report the crystal structure of Sa Mtg E100Q mutant in complex with the inhibitor moenomycin to 2.1A resolution. The co-crystal structure revealed detailed interactions between the protein and inhibitor including portions of the polycarbon tail of moenomycin. The structure also contained an ordered phosphate ion which helped to identify the Lipid II binding site.
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Affiliation(s)
- Holly Heaslet
- Antibacterial Discovery Chemistry, Pfizer Global Research & Development, Groton, CT 06340, USA
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33
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Terrak M, Sauvage E, Derouaux A, Dehareng D, Bouhss A, Breukink E, Jeanjean S, Nguyen-Distèche M. Importance of the conserved residues in the peptidoglycan glycosyltransferase module of the class A penicillin-binding protein 1b of Escherichia coli. J Biol Chem 2008; 283:28464-70. [PMID: 18701463 DOI: 10.1074/jbc.m803223200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The peptidoglycan glycosyltransferase (GT) module of class A penicillin-binding proteins (PBPs) and monofunctional GTs catalyze glycan chain elongation of the bacterial cell wall. These enzymes belong to the GT51 family, are characterized by five conserved motifs, and have some fold similarity with the phage lambda lysozyme. In this work, we have systematically modified all the conserved amino acid residues of the GT module of Escherichia coli class A PBP1b by site-directed mutagenesis and determined their importance for the in vivo and in vitro activity and the thermostability of the protein. To get an insight into the GT active site of this paradigm enzyme, a model of PBP1b GT domain was constructed based on the available crystal structures (PDB codes 2OLV and 2OLU). The data show that in addition to the essential glutamate residues Glu233 of motif 1 and Glu290 of motif 3, the residues Phe237 and His240 of motif 1 and Gly264, Thr267, Gln271, and Lys274 of motif 2, all located in the catalytic cavity of the GT domain, are essential for the in vitro enzymatic activity of the PBP1b and for its in vivo functioning. Thus, the first three conserved motifs contain most of the residues that are required for the GT activity of the PBP1b. The residues Asp234, Phe237, His240, Thr267, and Gln271 are proposed to maintain the structure of the active site and the positioning of the catalytic Glu233.
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Affiliation(s)
- Mohammed Terrak
- Centre d'Ingénierie des Protéines, Institut de Chimie, Université de Liège, B6a, B-4000 Sart-Tilman, Belgium.
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Yuan Y, Fuse S, Ostash B, Sliz P, Kahne D, Walker S. Structural analysis of the contacts anchoring moenomycin to peptidoglycan glycosyltransferases and implications for antibiotic design. ACS Chem Biol 2008; 3:429-36. [PMID: 18642800 DOI: 10.1021/cb800078a] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Peptidoglycan glycosyltransferases (PGTs), enzymes that catalyze the formation of the glycan chains of the bacterial cell wall, have tremendous potential as antibiotic targets. The moenomycins, a potent family of natural product antibiotics, are the only known active site inhibitors of the PGTs and serve as blueprints for the structure-based design of new antibacterials. A 2.8 A structure of a Staphylococcus aureus PGT with moenomycin A bound in the active site appeared recently, potentially providing insight into substrate binding; however, the protein-ligand contacts were not analyzed in detail and the implications of the structure for inhibitor design were not addressed. We report here the 2.3 A structure of a complex of neryl-moenomycin A bound to the PGT domain of Aquifex aeolicus PBP1A. The structure allows us to examine protein-ligand contacts in detail and implies that six conserved active site residues contact the centrally located F-ring phosphoglycerate portion of neryl-moenomycin A. A mutational analysis shows that all six residues play important roles in enzymatic activity. We suggest that small scaffolds that maintain these key contacts will serve as effective PGT inhibitors. To test this hypothesis, we have prepared, via heterologous expression of a subset of moenomycin biosynthetic genes, a novel moenomycin intermediate that maintains these six contacts but does not contain the putative minimal pharmacophore. This compound has comparable biological activity to the previously proposed minimal pharmacophore. The results reported here may facilitate the design of antibiotics targeted against peptidoglycan glycosyltransferases.
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Affiliation(s)
- Yanqiu Yuan
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Shinichiro Fuse
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Bohdan Ostash
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Piotr Sliz
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
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Abstract
This review is an attempt to bring together and critically evaluate the now-abundant but dispersed data concerning the lipid intermediates of the biosynthesis of bacterial peptidoglycan. Lipid I, lipid II, and their modified forms play a key role not only as the specific link between the intracellular synthesis of the peptidoglycan monomer unit and the extracytoplasmic polymerization reactions but also in the attachment of proteins to the bacterial cell wall and in the mechanisms of action of antibiotics with which they form specific complexes. The survey deals first with their detection, purification, structure, and preparation by chemical and enzymatic methods. The recent important advances in the study of transferases MraY and MurG, responsible for the formation of lipids I and II, are reported. Various modifications undergone by lipids I and II are described, especially those occurring in gram-positive organisms. The following section concerns the cellular location of the lipid intermediates and the translocation of lipid II across the cytoplasmic membrane. The great efforts made since 2000 in the study of the glycosyltransferases catalyzing the glycan chain formation with lipid II or analogues are analyzed in detail. Finally, examples of antibiotics forming complexes with the lipid intermediates are presented.
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Sauvage E, Kerff F, Terrak M, Ayala JA, Charlier P. The penicillin-binding proteins: structure and role in peptidoglycan biosynthesis. FEMS Microbiol Rev 2008; 32:234-58. [PMID: 18266856 DOI: 10.1111/j.1574-6976.2008.00105.x] [Citation(s) in RCA: 860] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Eric Sauvage
- Centre d'Ingénierie des Protéines, Institut de Physique B5a et Institut de Chimie B6a, University of Liège, Sart Tilman, Belgium.
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The monofunctional glycosyltransferase of Escherichia coli localizes to the cell division site and interacts with penicillin-binding protein 3, FtsW, and FtsN. J Bacteriol 2007; 190:1831-4. [PMID: 18165305 DOI: 10.1128/jb.01377-07] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The monofunctional peptidoglycan glycosyltransferase (MtgA) catalyzes glycan chain elongation of the bacterial cell wall. Here we show that MtgA localizes at the division site of Escherichia coli cells that are deficient in PBP1b and produce a thermosensitive PBP1a and is able to interact with three constituents of the divisome, PBP3, FtsW, and FtsN, suggesting that MtgA may play a role in peptidoglycan assembly during the cell cycle in collaboration with other proteins.
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Hübscher J, Jansen A, Kotte O, Schäfer J, Majcherczyk PA, Harris LG, Bierbaum G, Heinemann M, Berger-Bächi B. Living with an imperfect cell wall: compensation of femAB inactivation in Staphylococcus aureus. BMC Genomics 2007; 8:307. [PMID: 17784943 PMCID: PMC2045680 DOI: 10.1186/1471-2164-8-307] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Accepted: 09/04/2007] [Indexed: 12/17/2022] Open
Abstract
Background Synthesis of the Staphylococcus aureus peptidoglycan pentaglycine interpeptide bridge is catalyzed by the nonribosomal peptidyl transferases FemX, FemA and FemB. Inactivation of the femAB operon reduces the interpeptide to a monoglycine, leading to a poorly crosslinked peptidoglycan. femAB mutants show a reduced growth rate and are hypersusceptible to virtually all antibiotics, including methicillin, making FemAB a potential target to restore β-lactam susceptibility in methicillin-resistant S. aureus (MRSA). Cis-complementation with wild type femAB only restores synthesis of the pentaglycine interpeptide and methicillin resistance, but the growth rate remains low. This study characterizes the adaptations that ensured survival of the cells after femAB inactivation. Results In addition to slow growth, the cis-complemented femAB mutant showed temperature sensitivity and a higher methicillin resistance than the wild type. Transcriptional profiling paired with reporter metabolite analysis revealed multiple changes in the global transcriptome. A number of transporters for sugars, glycerol, and glycine betaine, some of which could serve as osmoprotectants, were upregulated. Striking differences were found in the transcription of several genes involved in nitrogen metabolism and the arginine-deiminase pathway, an alternative for ATP production. In addition, microarray data indicated enhanced expression of virulence factors that correlated with premature expression of the global regulators sae, sarA, and agr. Conclusion Survival under conditions preventing normal cell wall formation triggered complex adaptations that incurred a fitness cost, showing the remarkable flexibility of S. aureus to circumvent cell wall damage. Potential FemAB inhibitors would have to be used in combination with other antibiotics to prevent selection of resistant survivors.
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Affiliation(s)
- Judith Hübscher
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Andrea Jansen
- Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Bonn, Germany
| | - Oliver Kotte
- Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland
| | | | - Paul A Majcherczyk
- Division of Infectious Diseases, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Llinos G Harris
- AO Research Institute, Davos, Switzerland
- School of Medicine, University of Wales Swansea, Swansea, UK
| | - Gabriele Bierbaum
- Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Bonn, Germany
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Barrett D, Wang TSA, Yuan Y, Zhang Y, Kahne D, Walker S. Analysis of glycan polymers produced by peptidoglycan glycosyltransferases. J Biol Chem 2007; 282:31964-71. [PMID: 17704540 PMCID: PMC4048933 DOI: 10.1074/jbc.m705440200] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial cells are surrounded by a cross-linked polymer called peptidoglycan, the integrity of which is necessary for cell survival. The carbohydrate chains that form the backbone of peptidoglycan are made by peptidoglycan glycosyltransferases (PGTs), highly conserved membrane-bound enzymes that are thought to be excellent targets for the development of new antibacterials. Although structural information on these enzymes recently became available, their mechanism is not well understood because of a dearth of methods to monitor PGT activity. Here we describe a direct, sensitive, and quantitative SDS-PAGE method to analyze PGT reactions. We apply this method to characterize the substrate specificity and product length profile for two different PGT domains, PBP1A from Aquifex aeolicus and PBP1A from Escherichia coli. We show that both disaccharide and tetrasaccharide diphospholipids (Lipid II and Lipid IV) serve as substrates for these PGTs, but the product distributions differ significantly depending on which substrate is used as the starting material. Reactions using the disaccharide substrate are more processive and yield much longer glycan products than reactions using the tetrasaccharide substrate. We also show that the SDS-PAGE method can be applied to provide information on the roles of invariant residues in catalysis. A comprehensive mutational analysis shows that the biggest contributor to turnover of 14 mutated residues is an invariant glutamate located in the center of the active site cleft. The assay and results described provide new information about the process by which PGTs assemble bacterial cell walls.
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Affiliation(s)
- Dianah Barrett
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Tsung-Shing Andrew Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Yanqiu Yuan
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Yi Zhang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
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40
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Vollmer W, Bertsche U. Murein (peptidoglycan) structure, architecture and biosynthesis in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:1714-34. [PMID: 17658458 DOI: 10.1016/j.bbamem.2007.06.007] [Citation(s) in RCA: 307] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/11/2007] [Accepted: 06/11/2007] [Indexed: 10/23/2022]
Abstract
The periplasmic murein (peptidoglycan) sacculus is a giant macromolecule made of glycan strands cross-linked by short peptides completely surrounding the cytoplasmic membrane to protect the cell from lysis due to its internal osmotic pressure. More than 50 different muropeptides are released from the sacculus by treatment with a muramidase. Escherichia coli has six murein synthases which enlarge the sacculus by transglycosylation and transpeptidation of lipid II precursor. A set of twelve periplasmic murein hydrolases (autolysins) release murein fragments during cell growth and division. Recent data on the in vitro murein synthesis activities of the murein synthases and on the interactions between murein synthases, hydrolases and cell cycle related proteins are being summarized. There are different models for the architecture of murein and for the incorporation of new precursor into the sacculus. We present a model in which morphogenesis of the rod-shaped E. coli is driven by cytoskeleton elements competing for the control over the murein synthesis multi-enzyme complexes.
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Affiliation(s)
- Waldemar Vollmer
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Catherine Cookson Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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Lovering AL, de Castro LH, Lim D, Strynadka NCJ. Structural Insight into the Transglycosylation Step of Bacterial Cell-Wall Biosynthesis. Science 2007; 315:1402-5. [PMID: 17347437 DOI: 10.1126/science.1136611] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Peptidoglycan glycosyltransferases (GTs) catalyze the polymerization step of cell-wall biosynthesis, are membrane-bound, and are highly conserved across all bacteria. Long considered the "holy grail" of antibiotic research, they represent an essential and easily accessible drug target for antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus. We have determined the 2.8 angstrom structure of a bifunctional cell-wall cross-linking enzyme, including its transpeptidase and GT domains, both unliganded and complexed with the substrate analog moenomycin. The peptidoglycan GTs adopt a fold distinct from those of other GT classes. The structures give insight into critical features of the catalytic mechanism and key interactions required for enzyme inhibition.
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Affiliation(s)
- Andrew L Lovering
- Department of Biochemistry and Molecular Biology, and Center for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada
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Yuan Y, Barrett D, Zhang Y, Kahne D, Sliz P, Walker S. Crystal structure of a peptidoglycan glycosyltransferase suggests a model for processive glycan chain synthesis. Proc Natl Acad Sci U S A 2007; 104:5348-53. [PMID: 17360321 PMCID: PMC1817829 DOI: 10.1073/pnas.0701160104] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Peptidoglycan is an essential polymer that forms a protective shell around bacterial cell membranes. Peptidoglycan biosynthesis is the target of many clinically used antibiotics, including the beta-lactams, imipenems, cephalosporins, and glycopeptides. Resistance to these and other antibiotics has prompted interest in an atomic-level understanding of the enzymes that make peptidoglycan. Representative structures have been reported for most of the enzymes in the pathway. Until now, however, there have been no structures of any peptidoglycan glycosyltransferases (also known as transglycosylases), which catalyze formation of the carbohydrate chains of peptidoglycan from disaccharide subunits on the bacterial cell surface. We report here the 2.1-A crystal structure of the peptidoglycan glycosyltransferase (PGT) domain of Aquifex aeolicus PBP1A. The structure has a different fold from all other glycosyltransferase structures reported to date, but it bears some resemblance to lambda-lysozyme, an enzyme that degrades the carbohydrate chains of peptidoglycan. An analysis of the structure, combined with biochemical information showing that these enzymes are processive, suggests a model for glycan chain polymerization.
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Affiliation(s)
- Yanqiu Yuan
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | - Dianah Barrett
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
| | - Yi Zhang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138; and
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138; and
- To whom correspondence may be addressed. E-mail: or
| | - Piotr Sliz
- Department of Biological Chemistry and Molecular Pharmacology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115
- To whom correspondence may be addressed. E-mail: or
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Liu H, Wong CH. Characterization of a transglycosylase domain of Streptococcus pneumoniae PBP1b. Bioorg Med Chem 2006; 14:7187-95. [PMID: 16870450 DOI: 10.1016/j.bmc.2006.06.058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 06/16/2006] [Accepted: 06/23/2006] [Indexed: 10/24/2022]
Abstract
Inhibitors of transglycosylases may serve as potent antibiotics that are less prone to resistance development in bacterial pathogens. To facilitate the search of such compounds, a transglycosylase (TGase) domain of the membrane integral multidomain Streptococcus pneumoniae PBP1b was cloned and expressed. This TGase domain was characterized by a substrate-dependent fluorescence coupled enzyme assay and an inhibitor-tethered surface plasmon resonance binding assay. Both assays show that the catalytic efficiency of the domain is comparable to that of the monofunctional transglycosylases, and it is fully active in the absence of other domains. The isolation of the active TGase domain makes it possible to screen for potential antibiotics targeting transglycosylases.
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Affiliation(s)
- Haitian Liu
- Department of Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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