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Cesur MF, Siraj B, Uddin R, Durmuş S, Çakır T. Network-Based Metabolism-Centered Screening of Potential Drug Targets in Klebsiella pneumoniae at Genome Scale. Front Cell Infect Microbiol 2020; 9:447. [PMID: 31993376 PMCID: PMC6970976 DOI: 10.3389/fcimb.2019.00447] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 12/12/2019] [Indexed: 01/28/2023] Open
Abstract
Klebsiella pneumoniae is an opportunistic bacterial pathogen leading to life-threatening nosocomial infections. Emergence of highly resistant strains poses a major challenge in the management of the infections by healthcare-associated K. pneumoniae isolates. Thus, despite intensive efforts, the current treatment strategies remain insufficient to eradicate such infections. Failure of the conventional infection-prevention and treatment efforts explicitly indicates the requirement of new therapeutic approaches. This prompted us to systematically analyze the K. pneumoniae metabolism to investigate drug targets. Genome-scale metabolic networks (GMNs) facilitating the systematic analysis of the metabolism are promising platforms. Thus, we used a GMN of K. pneumoniae MGH 78578 to determine putative targets through gene- and metabolite-centric approaches. To develop more realistic infection models, we performed the bacterial growth simulations within different host-mimicking media, using an improved biomass formation reaction. We selected more suitable targets based on several property-based prioritization procedures. KdsA was identified as the high-ranked putative target satisfying most of the target prioritization criteria specified under the gene-centric approach. Through a structure-based virtual screening protocol, we identified potential KdsA inhibitors. In addition, the metabolite-centric approach extended the drug target list based on synthetic lethality. This revealed the importance of combined metabolic analyses for a better understanding of the metabolism. To our knowledge, this is the first comprehensive effort on the investigation of the K. pneumoniae metabolism for drug target prediction through the constraint-based analysis of its GMN in conjunction with several bioinformatic approaches. This study can guide the researchers for the future drug designs by providing initial findings regarding crucial components of the Klebsiella metabolism.
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Affiliation(s)
- Müberra Fatma Cesur
- Computational Systems Biology Group, Department of Bioengineering, Gebze Technical University, Gebze, Turkey
| | - Bushra Siraj
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Reaz Uddin
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Saliha Durmuş
- Computational Systems Biology Group, Department of Bioengineering, Gebze Technical University, Gebze, Turkey
| | - Tunahan Çakır
- Computational Systems Biology Group, Department of Bioengineering, Gebze Technical University, Gebze, Turkey
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Chen X, Wong CH, Ma C. Targeting the Bacterial Transglycosylase: Antibiotic Development from a Structural Perspective. ACS Infect Dis 2019; 5:1493-1504. [PMID: 31283163 DOI: 10.1021/acsinfecdis.9b00118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
One of the major threats to human life nowadays is widespread antibiotic resistance. Antibiotics are used to treat bacterial infections by targeting their essential pathways, such as the biosynthesis of bacterial cell walls. Bacterial transglycosylase, particularly glycosyltransferase family 51 (GT51), is one critical player in the cell wall biosynthesis and has long been known as a promising yet challenging target for antibiotic development. Here, we review the structural studies of this protein and summarize recent progress in developing its specific inhibitors, including synthetic substrate analogs and novel compounds identified from high-throughput screens. A detailed analysis of the protein-ligand interface has also provided us with valuable insights into the future antibiotic development against the bacterial transglycosylase.
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Affiliation(s)
- Xiaorui Chen
- Genomics Research Center, Academia Sinica, No. 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan
| | - Chi-Huey Wong
- Genomics Research Center, Academia Sinica, No. 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan
| | - Che Ma
- Genomics Research Center, Academia Sinica, No. 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan
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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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Kumar VP, Basavannacharya C, de Sousa SM. A microplate assay for the coupled transglycosylase-transpeptidase activity of the penicillin binding proteins; a vancomycin-neutralizing tripeptide combination prevents penicillin inhibition of peptidoglycan synthesis. Biochem Biophys Res Commun 2014; 450:347-52. [PMID: 24944023 DOI: 10.1016/j.bbrc.2014.05.119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 05/25/2014] [Indexed: 12/11/2022]
Abstract
A microplate, scintillation proximity assay to measure the coupled transglycosylase-transpeptidase activity of the penicillin binding proteins in Escherichia coli membranes was developed. Membranes were incubated with the two peptidoglycan sugar precursors UDP-N-acetyl muramylpentapeptide (UDP-MurNAc(pp)) and UDP-[(3)H]N-acetylglucosamine in the presence of 40 μM vancomycin to allow in situ accumulation of lipid II. In a second step, vancomycin inhibition was relieved by addition of a tripeptide (Lys-D-ala-D-ala) or UDP-MurNAc(pp), resulting in conversion of lipid II to cross-linked peptidoglycan. Inhibitors of the transglycosylase or transpeptidase were added at step 2. Moenomycin, a transglycosylase inhibitor, had an IC50 of 8 nM. Vancomycin and nisin also inhibited the assay. Surprisingly, the transpeptidase inhibitors penicillin and ampicillin showed no inhibition. In a pathway assay of peptidoglycan synthesis, starting from the UDP linked sugar precursors, inhibition by penicillin was reversed by a 'neutral' combination of vancomycin plus tripeptide, suggesting an interaction thus far unreported.
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Helassa N, Vollmer W, Breukink E, Vernet T, Zapun A. The membrane anchor of penicillin-binding protein PBP2a from Streptococcus pneumoniae influences peptidoglycan chain length. FEBS J 2012; 279:2071-81. [DOI: 10.1111/j.1742-4658.2012.08592.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Meng FC, Chen KT, Huang LY, Shih HW, Chang HH, Nien FY, Liang PH, Cheng TJR, Wong CH, Cheng WC. Total synthesis of polyprenyl N-glycolyl lipid II as a mycobacterial transglycosylase substrate. Org Lett 2011; 13:5306-9. [PMID: 21913698 DOI: 10.1021/ol2021687] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A feasible synthetic approach toward the Mycobacterium tuberculosis (Mtb) N-glycolyl lipid II-like molecule 1 is described. Compound 1 bears pendant undecaprenol and l-lysin moieties instead of the naturally occurring decaprenol and meso-diaminopimelic acid, which are not readily available. Functionalization of 1 with a fluorophore on the peptide side chain gave 14, which was found to be recognized as an Mtb TGase substrate. This result suggests it has tremendous utility for mechanistic studies, the characterization of mycobacterial enzymes, and mycobacterial TGase inhibitor evaluation.
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Affiliation(s)
- Fan-Chun Meng
- The Genomics Research Center, Academia Sinica, Nankang, Taipei, Taiwan
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Ostash B, Walker S. Moenomycin family antibiotics: chemical synthesis, biosynthesis, and biological activity. Nat Prod Rep 2010; 27:1594-617. [PMID: 20730219 PMCID: PMC2987538 DOI: 10.1039/c001461n] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The review (with 214 references cited) is devoted to moenomycins, the only known group of antibiotics that directly inhibit bacterial peptidoglycan glycosytransferases. Naturally occurring moenomycins and chemical and biological approaches to their derivatives are described. The biological properties of moenomycins and plausible mechanisms of bacterial resistance to them are also covered here, portraying a complete picture of the chemistry and biology of these fascinating natural products
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Affiliation(s)
- Bohdan Ostash
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave., Armenise Bldg. 2, Rm 630, Boston, MA 02115, USA
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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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9
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Domain requirement of moenomycin binding to bifunctional transglycosylases and development of high-throughput discovery of antibiotics. Proc Natl Acad Sci U S A 2008; 105:431-6. [PMID: 18182485 DOI: 10.1073/pnas.0710868105] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Moenomycin inhibits bacterial growth by blocking the transglycosylase activity of class A penicillin-binding proteins (PBPs), which are key enzymes in bacterial cell wall synthesis. We compared the binding affinities of moenomycin A with various truncated PBPs by using surface plasmon resonance analysis and found that the transmembrane domain is important for moenomycin binding. Full-length class A PBPs from 16 bacterial species were produced, and their binding activities showed a correlation with the antimicrobial activity of moenomycin against Enterococcus faecalis and Staphylococcus aureus. On the basis of these findings, a fluorescence anisotropy-based high-throughput assay was developed and used successfully for identification of transglycosylase inhibitors.
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Barry CE, Crick DC, McNeil MR. Targeting the formation of the cell wall core of M. tuberculosis. Infect Disord Drug Targets 2007; 7:182-202. [PMID: 17970228 PMCID: PMC4747060 DOI: 10.2174/187152607781001808] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Mycobacteria have a unique cell wall, which is rich in drug targets. The cell wall core consists of a peptidoglycan layer, a mycolic acid layer, and an arabinogalactan polysaccharide connecting them. The detailed structure of the cell wall core is largely, although not completely, understood and will be presented. The biosynthetic pathways of all three components reveal significant drug targets that are the basis of present drugs and/or have potential for new drugs. These pathways will be reviewed and include enzymes involved in polyisoprene biosynthesis, soluble arabinogalactan precursor production, arabinogalactan polymerization, fatty acid synthesis, mycolate maturation, and soluble peptidoglycan precursor formation. Information relevant to targeting all these enzymes will be presented in tabular form. Selected enzymes will then be discussed in more detail. It is thus hoped this chapter will aid in the selection of targets for new drugs to combat tuberculosis.
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Affiliation(s)
- Clifton E. Barry
- Tuberculosis Research Section, Laboratory of Host Defense, NIAID, NIH, Twinbrook 2, Room 239, 12441 Parklawn Drive, Rockville, MD 20852
| | - Dean C. Crick
- Mycobacterial Research Laboratories, Dept. of Microbiology, Immunology, and Pathology, 1682 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1682
| | - Michael R. McNeil
- Mycobacterial Research Laboratories, Dept. of Microbiology, Immunology, and Pathology, 1682 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1682
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Ramachandran V, Chandrakala B, Kumar VP, Usha V, Solapure SM, de Sousa SM. Screen for inhibitors of the coupled transglycosylase-transpeptidase of peptidoglycan biosynthesis in Escherichia coli. Antimicrob Agents Chemother 2006; 50:1425-32. [PMID: 16569861 PMCID: PMC1426922 DOI: 10.1128/aac.50.4.1425-1432.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2005] [Revised: 01/11/2006] [Accepted: 02/03/2006] [Indexed: 11/20/2022] Open
Abstract
Class A high-molecular-weight penicillin-binding protein 1a (PBP1a) and PBP1b of Escherichia coli have both transglycosylase (TG) and transpeptidase (TP) activity. These enzymes are difficult to assay, since their substrates are difficult to prepare. We show the activity of PBP1a or PBP1b can be measured in membranes by cloning the PBP into an E. coli ponB::Spcr strain. Using this assay, we show that PBP1a is approximately 10-fold more sensitive to penicillin than PBP1b and that the 50% inhibitory concentration (IC50) of moenomycin, a TG inhibitor, is approximately 10-fold higher in the PBP transformants than in wild-type membranes; this increase in IC50 in transformants can be used to test the specificity of test compounds for inhibition of the TG. Alternatively, the coupled TG-TP activity of PBP1b can be directly measured in a two-step microplate assay. In the first step, radiolabeled lipid II, the TG substrate, was made in membranes of the E. coli ponB::Spcr strain by incubation with the peptidoglycan sugar precursors. In the second step, the TG-TP activity was assayed by adding a source of PBP1b to the membranes. The coupled TG-TP activity converts lipid II to cross-linked peptidoglycan, which was specifically captured by wheat germ agglutinin-coated scintillation proximity beads in the presence of 0.2% Sarkosyl (B. Chandrakala et al., Antimicrob. Agents Chemother. 48:30-40, 2004). The TG-TP assay was inhibited by penicillin and moenomycin as expected. Surprisingly, tunicamycin and nisin also inhibited the assay, and paper chromatography analysis revealed that both inhibited the transglycosylase. The assay can be used to screen for novel antibacterial agents.
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12
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Ostash B, Walker S. Bacterial transglycosylase inhibitors. Curr Opin Chem Biol 2006; 9:459-66. [PMID: 16118062 DOI: 10.1016/j.cbpa.2005.08.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Accepted: 08/12/2005] [Indexed: 12/01/2022]
Abstract
The spread of bacterial resistance to known antibiotics has inspired interest in previously under-exploited drug targets. The transglycosylation reaction remains a 'black box' in the generally well-studied process of bacterial peptidoglycan biosynthesis, which is a very attractive target for chemotherapeutic intervention. Here, we summarize recent progress in the study of bacterial transglycosylases and the compounds that inhibit them. The transglycosylation reaction is readily targeted by several different classes of natural products, implying that it should be possible to develop drugs that inhibit this process once efficient high-throughput screens and appropriate compound libraries have been developed.
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Affiliation(s)
- Bohdan Ostash
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
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Silver LL. Does the cell wall of bacteria remain a viable source of targets for novel antibiotics? Biochem Pharmacol 2005; 71:996-1005. [PMID: 16290173 DOI: 10.1016/j.bcp.2005.10.029] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2005] [Revised: 10/13/2005] [Accepted: 10/17/2005] [Indexed: 11/19/2022]
Abstract
Whether the bacterial cell wall remains a viable source of novel antibacterials is addressed here by reviewing screen and design strategies for discovery of antibacterials with a focus on their output. Inhibitors for which antibacterial activity has been shown to be due to specific inhibition of a reaction (antibacterially validated inhibitors) are known for 8 of the 14 conserved essential steps of the pathway. Antibacterially validated enzyme inhibitors exist for six of these steps. The possible obstacles to finding validated inhibitors of the remaining enzymes are discussed and some strategies are suggested.
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Affiliation(s)
- Lynn L Silver
- LL Silver Consulting (LLC), 3403 Park Place, Springfield, NJ 07081, USA.
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14
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Bertsche U, Breukink E, Kast T, Vollmer W. In Vitro Murein (Peptidoglycan) Synthesis by Dimers of the Bifunctional Transglycosylase-Transpeptidase PBP1B from Escherichia coli. J Biol Chem 2005; 280:38096-101. [PMID: 16154998 DOI: 10.1074/jbc.m508646200] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PBP1B is a major bifunctional murein (peptidoglycan) synthase catalyzing transglycosylation and transpeptidation reactions in Escherichia coli. PBP1B has been shown to form dimers in vivo. The K(D) value for PBP1B dimerization was determined by surface plasmon resonance. The effect of the dimerization of PBP1B on its activities was studied with a newly developed in vitro murein synthesis assay with radioactively labeled lipid II precursor as substrate. Under conditions at which PBP1B dimerizes, the enzyme synthesized murein with long glycan strands (>25 disaccharide units) and with almost 50% of the peptides being part of cross-links. PBP1B was also capable of synthesizing trimeric muropeptide structures. Tri-, tetra-, and pentapeptide compounds could serve as acceptors in the PBP1B-catalyzed transpeptidation reaction.
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Affiliation(s)
- Ute Bertsche
- Mikrobielle Genetik, Universität Tübingen, Germany
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Chandrakala B, Shandil RK, Mehra U, Ravishankar S, Kaur P, Usha V, Joe B, deSousa SM. High-throughput screen for inhibitors of transglycosylase and/or transpeptidase activities of Escherichia coli penicillin binding protein 1b. Antimicrob Agents Chemother 2004; 48:30-40. [PMID: 14693515 PMCID: PMC310179 DOI: 10.1128/aac.48.1.30-40.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Penicillin binding protein (PBP) 1b of Escherichia coli has both transglycosylase and transpeptidase activities, which are attractive targets for the discovery of new antibacterial agents. A high-throughput assay that detects inhibitors of the PBPs was described previously, but it cannot distinguish them from inhibitors of the MraY, MurG, and lipid pyrophosphorylase. We report on a method that distinguishes inhibitors of both activities of the PBPs from those of the other three enzymes. Radioactive peptidoglycan was synthesized by using E. coli membranes. Following termination of the reaction the products were analyzed in three ways. Wheat germ agglutinin (WGA)-coated scintillation proximity assay (SPA) beads were added to one set, and the same beads together with a detergent were added to a second set. Type A polyethylenimine-coated WGA-coated SPA beads were added to a third set. By comparison of the results of assays run in parallel under the first two conditions, inhibitors of the transpeptidase and transglycosylase could be distinguished from inhibitors of the other enzymes, as the inhibitors of the other enzymes showed similar inhibitory concentrations (IC(50)s) under both conditions but the inhibitors of the PBPs showed insignificant inhibition in the absence of detergent. Furthermore, comparison of the results of assays run under conditions two and three enabled the distinction of transpeptidase inhibitors. Penicillin and other beta-lactams showed insignificant inhibition with type A beads compared with that shown with WGA-coated SPA beads plus detergent. However, inhibitors of the other four enzymes (tunicamycin, nisin, bacitracin, and moenomycin) showed similar IC(50)s under both conditions. We show that the main PBP being measured under these conditions is PBP 1b. This screen can be used to find novel transglycosylase or transpeptidase inhibitors.
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Affiliation(s)
- B Chandrakala
- AstraZeneca India Pvt. Ltd., Bangalore 560 024, India
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References. Antibiotics (Basel) 2003. [DOI: 10.1128/9781555817886.refs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Chopra I, Hesse L, O'Neill A. Exploiting current understanding of antibiotic action for discovery of new drugs. J Appl Microbiol 2002. [DOI: 10.1046/j.1365-2672.92.5s1.13.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Abstract
This review focuses on target-based approaches for developing new chemical classes of antibacterial agents aimed at the bacterial cell wall. The clinical success of antibiotics such as beta-lactams and glycopeptides validates this chemotherapeutic strategy and emerging resistance to these agents warrants the development of new antibacterial drugs. Understanding the mechanism of action and resistance to beta-lactams and glycopeptides at a molecular level has supported the development of new agents that prevent transpeptidation and transglycosylation reactions of peptidoglycan polymerisation. The enzymes involved in the synthesis of the peptidoglycan structural unit have also been targeted for antibacterial discovery. The influence of bacterial genetics and genomics, structural biology, assay development and the properties of known inhibitors on these approaches will be discussed in the context of drug discovery.
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Affiliation(s)
- David W Green
- Cubist Pharmaceuticals, Inc., 65 Hayden Ave., Lexington, MA 02421, USA.
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van Heijenoort J. Formation of the glycan chains in the synthesis of bacterial peptidoglycan. Glycobiology 2001; 11:25R-36R. [PMID: 11320055 DOI: 10.1093/glycob/11.3.25r] [Citation(s) in RCA: 344] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The main structural features of bacterial peptidoglycan are linear glycan chains interlinked by short peptides. The glycan chains are composed of alternating units of N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc), all linkages between sugars being beta,1-->4. On the outside of the cytoplasmic membrane, two types of activities are involved in the polymerization of the peptidoglycan monomer unit: glycosyltransferases that catalyze the formation of the linear glycan chains and transpeptidases that catalyze the formation of the peptide cross-bridges. Contrary to the transpeptidation step, for which there is an abundant literature that has been regularly reviewed, the transglycosylation step has been studied to a far lesser extent. The aim of the present review is to summarize and evaluate the molecular and cellullar data concerning the formation of the glycan chains in the synthesis of peptidoglycan. Early work concerned the use of various in vivo and in vitro systems for the study of the polymerization steps, the attachment of newly made material to preexisting peptidoglycan, and the mechanism of action of antibiotics. The synthesis of the glycan chains is catalyzed by the N-terminal glycosyltransferase module of class A high-molecular-mass penicillin-binding proteins and by nonpenicillin-binding monofunctional glycosyltransferases. The multiplicity of these activities in a given organism presumably reflects a variety of in vivo functions. The topological localization of the incorporation of nascent peptidoglycan into the cell wall has revealed that bacteria have at least two peptidoglycan-synthesizing systems: one for septation, the other one for elongation or cell wall thickening. Owing to its location on the outside of the cytoplasmic membrane and its specificity, the transglycosylation step is an interesting target for antibacterials. Glycopeptides and moenomycins are the best studied antibiotics known to interfere with this step. Their mode of action and structure-activity relationships have been extensively studied. Attempts to synthesize other specific transglycosylation inhibitors have recently been made.
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Affiliation(s)
- J van Heijenoort
- Institut de Biochimie, Bat 430, Université Paris-Sud, Orsay, F-91405, France
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Chandrakala B, Elias BC, Mehra U, Umapathy NS, Dwarakanath P, Balganesh TS, deSousa SM. Novel scintillation proximity assay for measuring membrane-associated steps of peptidoglycan biosynthesis in Escherichia coli. Antimicrob Agents Chemother 2001; 45:768-75. [PMID: 11181358 PMCID: PMC90371 DOI: 10.1128/aac.45.3.768-775.2001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have developed a novel, high-throughput scintillation proximity assay to measure the membrane-associated steps (stages 2 and 3) of peptidoglycan synthesis in Escherichia coli. At least five enzymes are involved in these two stages, all of which are thought to be essential for the survival of the cell. The individual enzymes are difficult to assay since the substrates are lipidic and difficult to isolate in large quantities and analysis is done by paper chromatography. We have assayed all five enzymes in a single mixture by monitoring synthesis of cross-linked peptidoglycan, which is the final product of the pathway. E. coli membranes are incubated with the two sugar precursors, UDP-N-acetyl muramylpentapeptide and UDP-[(3)H]-N-acetylglucosamine. The radiolabel is incorporated into peptidoglycan, which is captured using wheat germ agglutinin-coated scintillation proximity assay beads. The assay monitors the activity of the translocase (MraY), the transferase (MurG), the lipid pyrophosphorylase, and the transglycosylase and transpeptidase activities of the penicillin-binding proteins. Vancomyin, tunicamycin, nisin, moenomycin, bacitracin, and penicillin inhibit the assay, and these inhibitors have been used to validate the assay. The search for new antimicrobial agents that act via the late stages of peptidoglycan biosynthesis can now be performed in high throughput in a microtiter plate.
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Affiliation(s)
- B Chandrakala
- AstraZeneca India Pvt. Ltd., Bangalore 560 003, India
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von Rechenberg M, Höltje JV. Two-step procedure for purification and separation of the essential penicillin-binding proteins PBP 1A and 1Bs of Escherichia coli. FEMS Microbiol Lett 2000; 189:201-4. [PMID: 10930738 DOI: 10.1111/j.1574-6968.2000.tb09230.x] [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: 11/28/2022] Open
Abstract
The penicillin-binding proteins PBP 1A and 1Bs are the essential murein polymerases of Escherichia coli. Purification of these membrane-bound bifunctional transglycosylase-transpeptidases was a major obstacle in studying the details of both enzymatic reactions. Here we describe a simple, highly specific affinity chromatography method that takes advantage of the availability of the specific inhibitor of the transglycosylase site moenomycin A in order to enrich PBP 1A and 1Bs in one step from crude membrane preparations. Separation of PBP 1A from PBP 1Bs is achieved in a second step employing cation exchange chromatography yielding enzymatically active native murein polymerases.
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Affiliation(s)
- M von Rechenberg
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Biochemie, Spemannstrasse 35, 72076, Tübingen, Germany
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