51
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Misra S, Sharma V, Srivastava AK. Bacterial Polysaccharides: An Overview. POLYSACCHARIDES 2014. [DOI: 10.1007/978-3-319-03751-6_68-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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52
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Leite CA, Cavallieri AP, Araujo MLGC. Enhancing effect of lysine combined with other compounds on cephamycin C production in Streptomyces clavuligerus. BMC Microbiol 2013; 13:296. [PMID: 24359569 PMCID: PMC3880171 DOI: 10.1186/1471-2180-13-296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/18/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lysine plays an important role in Streptomyces clavuligerus metabolism; it takes part in its catabolism, via cadaverine, and in its secondary metabolism, in which lysine is converted via 1-piperideine-6-carboxylate to alpha-aminoadipic acid, a beta-lactam antibiotic precursor. The role of lysine as an enhancer of cephamycin C production, when added to production medium at concentrations above 50 mmol l(-1), has already been reported in the literature, with some studies attributing a positive influence to multifunctional diamines, among other compounds. However, there is a lack of research on the combined effect of these compounds on antibiotic production. RESULTS Results from experimental design-based tests were used to conduct response surface-based optimization studies in order to investigate the synergistic effect of combining lysine with cadaverine, putrescine, 1,3-diaminopropane, or alpha-aminoadipic acid on cephamycin C volumetric production. Lysine combined with cadaverine influenced production positively, but only at low lysine concentrations. On the whole, higher putrescine concentrations (0.4 g l(-1)) affected negatively cephamycin C volumetric production. In comparison to culture media containing only lysine as additive, combinations of this amino acid with alpha-aminoadipic acid or 1,3-diaminopropane increased cephamycin C production by more than 100%. CONCLUSION This study demonstrated that different combinations of lysine with diamines or lysine with alpha-aminoadipic acid engender significant differences with respect to antibiotic volumetric production, with emphasis on the benefits observed for lysine combined with alpha-aminoadipic acid or 1,3-diaminopropane. This increase is explained by mathematical models and demonstrated by means of bioreactor cultivations. Moreover, it is consistent with the positive influence of these compounds on lysine conversion to alpha-aminoadipic acid, a limiting step in cephamycin C production.
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Affiliation(s)
- Carla A Leite
- Department of Biochemistry and Technological Chemistry, UNESP - São Paulo State University, Institute of Chemistry, 14800-900 Araraquara, SP, Brazil
| | - André P Cavallieri
- Department of Biochemistry and Technological Chemistry, UNESP - São Paulo State University, Institute of Chemistry, 14800-900 Araraquara, SP, Brazil
| | - Maria L G C Araujo
- Department of Biochemistry and Technological Chemistry, UNESP - São Paulo State University, Institute of Chemistry, 14800-900 Araraquara, SP, Brazil
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Komoike Y, Matsuoka M. Exposure to tributyltin induces endoplasmic reticulum stress and the unfolded protein response in zebrafish. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 142-143:221-229. [PMID: 24055755 DOI: 10.1016/j.aquatox.2013.08.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/22/2013] [Accepted: 08/27/2013] [Indexed: 06/02/2023]
Abstract
Tributyltin (TBT) is a major marine contaminant and causes endocrine disruption, hepatotoxicity, immunotoxicity, and neurotoxicity. However, the molecular mechanisms underlying the toxicity of TBT have not been fully elucidated. We examined whether exposure to TBT induces the endoplasmic reticulum (ER) stress response in zebrafish, a model organism. Zebrafish-derived BRF41 fibroblast cells were exposed to 0.5 or 1 μM TBT for 0.5-16 h and subsequently lysed and immunoblotted to detect ER stress-related proteins. Zebrafish embryos, grown until 32 h post fertilization (hpf), were exposed to 1 μM TBT for 16 h and used in whole mount in situ hybridization and immunohistochemistry to visualize the expression of ER chaperones and an ER stress-related apoptosis factor. Exposure of the BRF41 cells to TBT caused phosphorylation of the zebrafish homolog of protein kinase RNA-activated-like ER kinase (PERK), eukaryotic translation initiation factor 2 alpha (eIF2α), and inositol-requiring enzyme 1 (IRE1), characteristic splicing of X-box binding protein 1 (XBP1) mRNA, and enhanced expression of activating transcription factor 4 (ATF4) protein. In TBT-exposed zebrafish embryos, ectopic expression of the gene encoding zebrafish homolog of the 78 kDa glucose-regulating protein (GRP78) and gene encoding CCAAT/enhancer-binding protein homologous protein (CHOP) was detected in the precursors of the neuromast, which is a sensory organ for detecting water flow and vibration. Our in vitro and in vivo studies revealed that exposure of zebrafish to TBT induces the ER stress response via activation of both the PERK-eIF2α and IRE1-XBP1 pathways of the unfolded protein response (UPR) in an organ-specific manner.
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Affiliation(s)
- Yuta Komoike
- Department of Hygiene and Public Health I, School of Medicine, Tokyo Women's Medical University, 8-1 Kawadacho, Shinjuku, Tokyo 162-8666, Japan.
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54
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The UDP-N-acetylglucosamine:dolichol phosphate-N-acetylglucosamine-phosphotransferase gene as a new selection marker for potato transformation. Biosci Biotechnol Biochem 2013; 77:1589-92. [PMID: 23832343 DOI: 10.1271/bbb.130146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Here we describe the generation of potato plants that constitutively overexpressed, UDP-N-acetylglucosamine:dolichol phosphate-N-acetylglucosamine-phosphotransferase (GPT). Such transgenic plants can be formed in a medium with tunicamycin at 9.8 ± 0.28% efficiency, similar to the 9.4 ± 1.10 for the bialaphos resistance gene (Bar) gene. This study indicated that GPT transformation was very stable with high reproducibility, and that growth and tuber production in the GPT-transformed plants were stronger than in the wild-type plants.
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55
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Schitter G, Wrodnigg TM. Update on carbohydrate-containing antibacterial agents. Expert Opin Drug Discov 2013; 4:315-56. [PMID: 23489128 DOI: 10.1517/17460440902778725] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Since the first known use of antibiotics > 2,500 years ago, a research field with immense importance for the welfare of mankind has been developed. After a decrease in interest in this topic by the end of the 20th century the occurrence of (poly-)resistant strains of bacteria induced a revival of antibiotics research. Health systems have been seeking viable and reliable solutions to this dangerous and expansive threat. OBJECTIVE This review will focus on carbohydrate-containing antibiotics and will give an outline of recently published novel isolated, semisynthetic as well as synthetic structures, their mechanism of action, if known, and the strategies for the design of compounds with potential by improved antibacterial properties. METHODS The literature between 2000 and 2008 was screened with main focus on recent examples of novel structures and strategies for the lead finding of exclusively antibacterial agents. RESULTS/CONCLUSION With the explanation of the role of the carbohydrate moieties in the respective antibacterial agents together with better synthetic strategies in carbohydrate chemistry as well as improvements in assay development for high throughput screening methods, carbohydrate-containing antibiotics can be used for the finding of potential drug leads that contribute to the fight against infections and diseases caused by (resistant) bacterial pathogens.
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Affiliation(s)
- Georg Schitter
- Technical University Graz, Institute of Organic Chemistry, Univ.-Doz. TMW, Dip.-Ing. GS, Glycogroup, A-8010 Graz, Austria +43 316 873 8744 ; +43 316 873 8740 ;
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56
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Farha MA, Leung A, Sewell EW, D’Elia MA, Allison SE, Ejim L, Pereira PM, Pinho MG, Wright GD, Brown ED. Inhibition of WTA synthesis blocks the cooperative action of PBPs and sensitizes MRSA to β-lactams. ACS Chem Biol 2013; 8:226-33. [PMID: 23062620 PMCID: PMC3552485 DOI: 10.1021/cb300413m] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Rising drug resistance is limiting treatment options
for infections
by methicillin-resistant Staphylococcus aureus (MRSA).
Herein we provide new evidence that wall teichoic acid (WTA) biogenesis
is a remarkable antibacterial target with the capacity to destabilize
the cooperative action of penicillin-binding proteins (PBPs) that
underlie β-lactam resistance in MRSA. Deletion of gene tarO, encoding the first step of WTA synthesis, resulted
in the restoration of sensitivity of MRSA to a unique profile of β-lactam
antibiotics with a known selectivity for penicillin binding protein
2 (PBP2). Of these, cefuroxime was used as a probe to screen for previously
approved drugs with a cryptic capacity to potentiate its activity
against MRSA. Ticlopidine, the antiplatelet drug Ticlid, strongly
potentiated cefuroxime, and this synergy was abolished in strains
lacking tarO. The combination was also effective
in a Galleria mellonella model of infection. Using
both genetic and biochemical strategies, we determined the molecular
target of ticlopidine as the N-acetylglucosamine-1-phosphate
transferase encoded in gene tarO and provide evidence
that WTA biogenesis represents an Achilles heel supporting the cooperative
function of PBP2 and PBP4 in creating highly cross-linked muropeptides
in the peptidoglycan of S. aureus. This approach
represents a new paradigm to tackle MRSA infection.
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Affiliation(s)
- Maya A. Farha
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Alexander Leung
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Edward W. Sewell
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Michael A. D’Elia
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Sarah E. Allison
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Linda Ejim
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Pedro M. Pereira
- Laboratory of Bacterial Cell
Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Mariana G. Pinho
- Laboratory of Bacterial Cell
Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras, Portugal
| | - Gerard D. Wright
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
| | - Eric D. Brown
- M. G. DeGroote
Institute for
Infectious Disease Research and Department of Biochemistry and Biomedical
Sciences, McMaster University, Hamilton,
Ontario, Canada L8N 3Z5
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Abstract
The peptidoglycan layers of many gram-positive bacteria are densely functionalized with anionic glycopolymers known as wall teichoic acids (WTAs). These polymers play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of gram-positive bacterial physiology. Additionally, WTAs are important in pathogenesis and play key roles in antibiotic resistance. We provide an overview of WTA structure and biosynthesis, review recent studies on the biological roles of these polymers, and highlight remaining questions. We also discuss prospects for exploiting WTA biosynthesis as a target for new therapies to overcome resistant infections.
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Affiliation(s)
- Stephanie Brown
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115;
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58
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Caliot É, Dramsi S, Chapot-Chartier MP, Courtin P, Kulakauskas S, Péchoux C, Trieu-Cuot P, Mistou MY. Role of the Group B antigen of Streptococcus agalactiae: a peptidoglycan-anchored polysaccharide involved in cell wall biogenesis. PLoS Pathog 2012; 8:e1002756. [PMID: 22719253 PMCID: PMC3375309 DOI: 10.1371/journal.ppat.1002756] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 05/03/2012] [Indexed: 11/18/2022] Open
Abstract
Streptococcus agalactiae (Group B streptococcus, GBS) is a leading cause of infections in neonates and an emerging pathogen in adults. The Lancefield Group B carbohydrate (GBC) is a peptidoglycan-anchored antigen that defines this species as a Group B Streptococcus. Despite earlier immunological and biochemical characterizations, the function of this abundant glycopolymer has never been addressed experimentally. Here, we inactivated the gene gbcO encoding a putative UDP-N-acetylglucosamine-1-phosphate:lipid phosphate transferase thought to catalyze the first step of GBC synthesis. Indeed, the gbcO mutant was unable to synthesize the GBC polymer, and displayed an important growth defect in vitro. Electron microscopy study of the GBC-depleted strain of S. agalactiae revealed a series of growth-related abnormalities: random placement of septa, defective cell division and separation processes, and aberrant cell morphology. Furthermore, vancomycin labeling and peptidoglycan structure analysis demonstrated that, in the absence of GBC, cells failed to initiate normal PG synthesis and cannot complete polymerization of the murein sacculus. Finally, the subcellular localization of the PG hydrolase PcsB, which has a critical role in cell division of streptococci, was altered in the gbcO mutant. Collectively, these findings show that GBC is an essential component of the cell wall of S. agalactiae whose function is reminiscent of that of conventional wall teichoic acids found in Staphylococcus aureus or Bacillus subtilis. Furthermore, our findings raise the possibility that GBC-like molecules play a major role in the growth of most if not all beta-hemolytic streptococci.
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Affiliation(s)
- Élise Caliot
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
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59
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Suzuki T, Campbell J, Kim Y, Swoboda JG, Mylonakis E, Walker S, Gilmore MS. Wall teichoic acid protects Staphylococcus aureus from inhibition by Congo red and other dyes. J Antimicrob Chemother 2012; 67:2143-51. [PMID: 22615298 DOI: 10.1093/jac/dks184] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVES Polyanionic polymers, including lipoteichoic acid and wall teichoic acid, are important determinants of the charged character of the staphylococcal cell wall. This study was designed to investigate the extent to which teichoic acid contributes to protection from anionic azo dyes and to identify barriers to drug penetration for development of new antibiotics for multidrug-resistant Staphylococcus aureus infection. METHODS We studied antimicrobial activity of azo dyes against S. aureus strains with or without inhibition of teichoic acid in vitro and in vivo. RESULTS We observed that inhibition of wall teichoic acid expression resulted in an ∼1000-fold increase in susceptibility to azo dyes such as Congo red, reducing its MIC from >1024 to <4 mg/L. Sensitization occurred when the first step in the wall teichoic acid pathway, catalysed by TarO, was inhibited either by mutation or by chemical inhibition. In contrast, genetic blockade of lipoteichoic acid biosynthesis did not confer Congo red susceptibility. Based on this finding, combination therapy was tested using the highly synergistic combination of Congo red plus tunicamycin at sub-MIC concentrations (to inhibit wall teichoic acid biosynthesis). The combination rescued Caenorhabditis elegans from a lethal challenge of S. aureus. CONCLUSIONS Our studies show that wall teichoic acid confers protection to S. aureus from anionic azo dyes and related compounds, and its inhibition raises the prospect of development of new combination therapies based on this inhibition.
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Affiliation(s)
- Takashi Suzuki
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
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60
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Villani GRD, Chierchia A, Di Napoli D, Di Natale P. Unfolded protein response is not activated in the mucopolysaccharidoses but protein disulfide isomerase 5 is deregulated. J Inherit Metab Dis 2012; 35:479-93. [PMID: 22002444 DOI: 10.1007/s10545-011-9403-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 09/15/2011] [Accepted: 09/16/2011] [Indexed: 01/03/2023]
Abstract
Mucopolysaccharidoses (MPSs) are lysosomal storage diseases (LSDs) caused by defects in lysosomal enzymes involved in the catabolism of glycosaminoglycans. The pathogenesis of these disorders is still not completely known, although inflammation and oxidative stress appear to be common mechanisms, as in all LSDs. Recently, it was hypothesized that endoplasmic reticulum (ER) stress followed by an unfolded protein response (UPR) could be another common pathogenetic mechanism in LSDs. The aim of the present study was to verify if the UPR was elicited in the mucopolysaccharidoses and if the mechanism was MPS type- and mutation-dependent. To this end, we analyzed the UPR in vitro, in fibroblasts from patients with different types of mucopolysaccharidoses (MPS I, II, IIIA, IIIB, IVA) and in vivo, in the murine MPS IIIB model. In both cases we found no changes in mRNA levels of several UPR-related genes, such as the spliced or unspliced form of Xbp-1, Bip, Chop, Edem1, Edem2, Edem3. Therefore, we report here that the unfolded protein response of the ER is not triggered either in vitro or in vivo; accordingly, cytotoxicity assays indicated that affected fibroblasts are no more sensitive to apoptosis induction than normal cells. However, our results show that in most of the analyzed MPS fibroblasts the expression of a poorly known protein belonging to the family of the protein disulfide isomerases, namely Pdia5, is upregulated; here we discuss if its upregulation could be an early event of ER stress possibly related to the severity of the damage induced in the mutant proteins.
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Affiliation(s)
- Guglielmo R D Villani
- Department of Biochemistry and Medical Biotechnologies, University of Naples Federico II, Via S. Pansini 5, 80131 Naples, Italy.
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61
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Bravo R, Vicencio JM, Parra V, Troncoso R, Munoz JP, Bui M, Quiroga C, Rodriguez AE, Verdejo HE, Ferreira J, Iglewski M, Chiong M, Simmen T, Zorzano A, Hill JA, Rothermel BA, Szabadkai G, Lavandero S. Increased ER-mitochondrial coupling promotes mitochondrial respiration and bioenergetics during early phases of ER stress. J Cell Sci 2011; 124:2143-52. [PMID: 21628424 PMCID: PMC3113668 DOI: 10.1242/jcs.080762] [Citation(s) in RCA: 421] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2011] [Indexed: 01/02/2023] Open
Abstract
Increasing evidence indicates that endoplasmic reticulum (ER) stress activates the adaptive unfolded protein response (UPR), but that beyond a certain degree of ER damage, this response triggers apoptotic pathways. The general mechanisms of the UPR and its apoptotic pathways are well characterized. However, the metabolic events that occur during the adaptive phase of ER stress, before the cell death response, remain unknown. Here, we show that, during the onset of ER stress, the reticular and mitochondrial networks are redistributed towards the perinuclear area and their points of connection are increased in a microtubule-dependent fashion. A localized increase in mitochondrial transmembrane potential is observed only in redistributed mitochondria, whereas mitochondria that remain in other subcellular zones display no significant changes. Spatial re-organization of these organelles correlates with an increase in ATP levels, oxygen consumption, reductive power and increased mitochondrial Ca²⁺ uptake. Accordingly, uncoupling of the organelles or blocking Ca²⁺ transfer impaired the metabolic response, rendering cells more vulnerable to ER stress. Overall, these data indicate that ER stress induces an early increase in mitochondrial metabolism that depends crucially upon organelle coupling and Ca²⁺ transfer, which, by enhancing cellular bioenergetics, establishes the metabolic basis for the adaptation to this response.
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Affiliation(s)
- Roberto Bravo
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Jose Miguel Vicencio
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Department of Cell and Developmental Biology and Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Valentina Parra
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Rodrigo Troncoso
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Juan Pablo Munoz
- Institute for Research in Biomedicine (IRB Barcelona) and Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona 08028, Spain
| | - Michael Bui
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Clara Quiroga
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Andrea E. Rodriguez
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Hugo E. Verdejo
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Department of Cardiovascular Diseases, Faculty of Medicine, P. Catholic University of Chile, Santiago, Chile
| | - Jorge Ferreira
- Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Myriam Iglewski
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mario Chiong
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
| | - Thomas Simmen
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona) and Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona 08028, Spain
| | - Joseph A. Hill
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Beverly A. Rothermel
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gyorgy Szabadkai
- Department of Cell and Developmental Biology and Consortium for Mitochondrial Research, University College London, London WC1E 6BT, UK
| | - Sergio Lavandero
- FONDAP Center for Molecular Studies of the Cell, Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago 8380492, Chile
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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62
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Suzuki T, Campbell J, Swoboda JG, Walker S, Gilmore MS. Role of wall teichoic acids in Staphylococcus aureus endophthalmitis. Invest Ophthalmol Vis Sci 2011; 52:3187-92. [PMID: 21345983 DOI: 10.1167/iovs.10-6558] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Wall teichoic acids (WTAs) are major polyanionic polymer components of the cell wall of Staphylococcus aureus. However, little is known about their role at the host-pathogen interface, especially in endophthalmitis. This study was designed to investigate the extent to which WTAs contribute to the pathogenicity of S. aureus in models of endophthalmitis and to determine whether there would be value in targeting their biosynthesis as a new therapeutic approach. METHODS S. aureus RN6390 and its isogenic WTA-null mutant (RN6390ΔtarO) were used to evaluate the role of WTAs in endophthalmitis. RN6390 and RN6390ΔtarO were cultured in bovine vitreous humor (VH) in vitro or inoculated into the vitreous chamber of C57B6 mice. Changes in the number of bacteria, organ function as determined by electroretinography (ERG), and histopathologic changes were assessed throughout the course of infection. In addition, the efficacy of WTA biosynthesis inhibitors in VH in vitro was examined. RESULTS It was observed that a component of VH synergized with WTA biosynthesis inhibitors in vitro and killed the S. aureus. This effect was also seen when mutants incapable of expressing WTA were exposed to VH. The killing activity of VH was lost on treatment with a protease inhibitor. RN6390ΔtarO could not survive in mouse eyes and did not affect organ function, nor was it able to establish endophthalmitis. CONCLUSIONS WTAs are essential cellular constituents for the manifestation of virulence by S. aureus in endophthalmitis, and appears to be a viable target for treating the endophthalmitis caused by S. aureus strains.
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Affiliation(s)
- Takashi Suzuki
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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63
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Campbell J, Singh AK, Santa Maria JP, Kim Y, Brown S, Swoboda JG, Mylonakis E, Wilkinson BJ, Walker S. Synthetic lethal compound combinations reveal a fundamental connection between wall teichoic acid and peptidoglycan biosyntheses in Staphylococcus aureus. ACS Chem Biol 2011; 6:106-16. [PMID: 20961110 DOI: 10.1021/cb100269f] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methicillin resistance in Staphylococcus aureus depends on the production of mecA, which encodes penicillin-binding protein 2A (PBP2A), an acquired peptidoglycan transpeptidase (TP) with reduced susceptibility to β-lactam antibiotics. PBP2A cross-links nascent peptidoglycan when the native TPs are inhibited by β-lactams. Although mecA expression is essential for β-lactam resistance, it is not sufficient. Here we show that blocking the expression of wall teichoic acids (WTAs) by inhibiting the first enzyme in the pathway, TarO, sensitizes methicillin-resistant S. aureus (MRSA) strains to β-lactams even though the β-lactam-resistant transpeptidase, PBP2A, is still expressed. The dramatic synergy between TarO inhibitors and β-lactams is noteworthy not simply because strategies to overcome MRSA are desperately needed but because neither TarO nor the activities of the native TPs are essential in MRSA strains. The "synthetic lethality" of inhibiting TarO and the native TPs suggests a functional connection between ongoing WTA expression and peptidoglycan assembly in S. aureus. Indeed, transmission electron microscopy shows that S. aureus cells blocked in WTA synthesis have extensive defects in septation and cell separation, indicating dysregulated cell wall assembly and degradation. Our studies imply that WTAs play a fundamental role in S. aureus cell division and raise the possibility that synthetic lethal compound combinations may have therapeutic utility for overcoming antibiotic-resistant bacterial infections.
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Affiliation(s)
- Jennifer Campbell
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Atul K. Singh
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
- School of Biological Science, Illinois State University, Normal, Illinois 61790, United States
| | - John P. Santa Maria
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Younghoon Kim
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Stephanie Brown
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Jonathan G. Swoboda
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Eleftherios Mylonakis
- Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Brian J. Wilkinson
- School of Biological Science, Illinois State University, Normal, Illinois 61790, United States
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
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64
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Yang Z, Chi X, Funabashi M, Baba S, Nonaka K, Pahari P, Unrine J, Jacobsen JM, Elliott GI, Rohr J, Van Lanen SG. Characterization of LipL as a non-heme, Fe(II)-dependent α-ketoglutarate:UMP dioxygenase that generates uridine-5'-aldehyde during A-90289 biosynthesis. J Biol Chem 2011; 286:7885-7892. [PMID: 21216959 DOI: 10.1074/jbc.m110.203562] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fe(II)- and α-ketoglutarate (α-KG)-dependent dioxygenases are a large and diverse superfamily of mononuclear, non-heme enzymes that perform a variety of oxidative transformations typically coupling oxidative decarboxylation of α-KG with hydroxylation of a prime substrate. The biosynthetic gene clusters for several nucleoside antibiotics that contain a modified uridine component, including the lipopeptidyl nucleoside A-90289 from Streptomyces sp. SANK 60405, have recently been reported, revealing a shared open reading frame with sequence similarity to proteins annotated as α-KG:taurine dioxygenases (TauD), a well characterized member of this dioxygenase superfamily. We now provide in vitro data to support the functional assignment of LipL, the putative TauD enzyme from the A-90289 gene cluster, as a non-heme, Fe(II)-dependent α-KG:UMP dioxygenase that produces uridine-5'-aldehyde to initiate the biosynthesis of the modified uridine component of A-90289. The activity of LipL is shown to be dependent on Fe(II), α-KG, and O(2), stimulated by ascorbic acid, and inhibited by several divalent metals. In the absence of the prime substrate UMP, LipL is able to catalyze oxidative decarboxylation of α-KG, although at a significantly reduced rate. The steady-state kinetic parameters using optimized conditions were determined to be K(m)(α-KG) = 7.5 μM, K(m)(UMP) = 14 μM, and k(cat) ≈ 80 min(-1). The discovery of this new activity not only sets the stage to explore the mechanism of LipL and related dioxygenases further but also has critical implications for delineating the biosynthetic pathway of several related nucleoside antibiotics.
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Affiliation(s)
- Zhaoyong Yang
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536
| | - Xiuling Chi
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536
| | - Masanori Funabashi
- Biopharmaceutical Research Group I, Biopharmaceutical Technology Research Laboratories, Pharmaceutical Technology Division, Daiichi Sankyo Co., Ltd., 389-4, Aza-ohtsurugi, Shimokawa, Izumi-machi, Iwaki-shi, Fukushima 971-8183, Japan, and
| | - Satoshi Baba
- Biopharmaceutical Research Group I, Biopharmaceutical Technology Research Laboratories, Pharmaceutical Technology Division, Daiichi Sankyo Co., Ltd., 389-4, Aza-ohtsurugi, Shimokawa, Izumi-machi, Iwaki-shi, Fukushima 971-8183, Japan, and
| | - Koichi Nonaka
- Biopharmaceutical Research Group I, Biopharmaceutical Technology Research Laboratories, Pharmaceutical Technology Division, Daiichi Sankyo Co., Ltd., 389-4, Aza-ohtsurugi, Shimokawa, Izumi-machi, Iwaki-shi, Fukushima 971-8183, Japan, and
| | - Pallab Pahari
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536
| | - Jason Unrine
- the Department of Plant and Soil Sciences, College of Agriculture, University of Kentucky, Lexington, Kentucky 40536
| | - Jesse M Jacobsen
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536
| | - Gregory I Elliott
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536
| | - Jürgen Rohr
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536
| | - Steven G Van Lanen
- From the Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536,.
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65
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Chen W, Qu D, Zhai L, Tao M, Wang Y, Lin S, Price NPJ, Deng Z. Characterization of the tunicamycin gene cluster unveiling unique steps involved in its biosynthesis. Protein Cell 2010; 1:1093-105. [PMID: 21153459 DOI: 10.1007/s13238-010-0127-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 10/26/2010] [Indexed: 01/03/2023] Open
Abstract
Tunicamycin, a potent reversible translocase I inhibitor, is produced by several Actinomycetes species. The tunicamycin structure is highly unusual, and contains an 11-carbon dialdose sugar and an α, β-1″,11'-glycosidic linkage. Here we report the identification of a gene cluster essential for tunicamycin biosynthesis by high-throughput heterologous expression (HHE) strategy combined with a bioassay. Introduction of the genes into heterologous non-producing Streptomyces hosts results in production of tunicamycin by these strains, demonstrating the role of the genes for the biosynthesis of tunicamycins. Gene disruption experiments coupled with bioinformatic analysis revealed that the tunicamycin gene cluster is minimally composed of 12 genes (tunA-tunL). Amongst these is a putative radical SAM enzyme (Tun B) with a potentially unique role in biosynthetic carbon-carbon bond formation. Hence, a seven-step novel pathway is proposed for tunicamycin biosynthesis. Moreover, two gene clusters for the potential biosynthesis of tunicamycin-like antibiotics were also identified in Streptomyces clavuligerus ATCC 27064 and Actinosynnema mirums DSM 43827. These data provide clarification of the novel mechanisms for tunicamycin biosynthesis, and for the generation of new-designer tunicamycin analogs with selective/enhanced bioactivity via combinatorial biosynthesis strategies.
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Affiliation(s)
- Wenqing Chen
- Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200030, China
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66
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Al-Hashimi AA, Caldwell J, Gonzalez-Gronow M, Pizzo SV, Aboumrad D, Pozza L, Al-Bayati H, Weitz JI, Stafford A, Chan H, Kapoor A, Jacobsen DW, Dickhout JG, Austin RC. Binding of anti-GRP78 autoantibodies to cell surface GRP78 increases tissue factor procoagulant activity via the release of calcium from endoplasmic reticulum stores. J Biol Chem 2010; 285:28912-23. [PMID: 20605795 DOI: 10.1074/jbc.m110.119107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The increased risk of venous thromboembolism in cancer patients has been attributed to enhanced tissue factor (TF) procoagulant activity (PCA) on the surface of cancer cells. Recent studies have shown that TF PCA can be modulated by GRP78, an endoplasmic reticulum (ER)-resident molecular chaperone. In this study, we investigated the role of cell surface GRP78 in modulating TF PCA in several human cancer cell lines. Although both GRP78 and TF are present on the cell surface of cancer cells, there was no evidence of a stable interaction between recombinant human GRP78 and TF, nor was there any effect of exogenously added recombinant GRP78 on cell surface TF PCA. Treatment of cells with the ER stress-inducing agent thapsigargin, an inhibitor of the sarco(endo)plasmic reticulum Ca(2+) pump that causes Ca(2+) efflux from ER stores, increased cytosolic [Ca(2+)] and induced TF PCA. Consistent with these findings, anti-GRP78 autoantibodies that were isolated from the serum of patients with prostate cancer and bind to a specific N-terminal epitope (Leu(98)-Leu(115)) on cell surface GRP78, caused a dose-dependent increase in cytosolic [Ca(2+)] and enhanced TF PCA. The ability to interfere with cell surface GRP78 binding, block phospholipase C activity, sequester ER Ca(2+), or prevent plasma membrane phosphatidylserine exposure resulted in a significant decrease in the TF PCA induced by anti-GRP78 autoantibodies. Taken together, these findings provide evidence that engagement of the anti-GRP78 autoantibodies with cell surface GRP78 increases TF PCA through a mechanism that involves the release of Ca(2+) from ER stores. Furthermore, blocking GRP78 signaling on the surface of cancer cells attenuates TF PCA and has the potential to reduce the risk of cancer-related venous thromboembolism.
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Affiliation(s)
- Ali A Al-Hashimi
- Department of Medicine and Division of Nephrology, St Joseph's Hospital and McMaster University, Hamilton, Ontario L8N 4A6, Canada
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67
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Swoboda JG, Campbell J, Meredith TC, Walker S. Wall teichoic acid function, biosynthesis, and inhibition. Chembiochem 2010; 11:35-45. [PMID: 19899094 DOI: 10.1002/cbic.200900557] [Citation(s) in RCA: 277] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Jonathan G Swoboda
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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68
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Wyszynski FJ, Hesketh AR, Bibb MJ, Davis BG. Dissecting tunicamycin biosynthesis by genome mining: cloning and heterologous expression of a minimal gene cluster. Chem Sci 2010. [DOI: 10.1039/c0sc00325e] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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69
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Kaysser L, Siebenberg S, Kammerer B, Gust B. Analysis of the Liposidomycin Gene Cluster Leads to the Identification of New Caprazamycin Derivatives. Chembiochem 2009; 11:191-6. [DOI: 10.1002/cbic.200900637] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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70
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Winn M, Goss RJM, Kimura KI, Bugg TDH. Antimicrobial nucleoside antibiotics targeting cell wall assembly: recent advances in structure-function studies and nucleoside biosynthesis. Nat Prod Rep 2009; 27:279-304. [PMID: 20111805 DOI: 10.1039/b816215h] [Citation(s) in RCA: 221] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The quest for new antibiotics, especially those with activity against Gram-negative bacteria, is urgent; however, very few new antibiotics have been marketed in the last 40 years, with this limited number falling into only four new structural classes. Several nucleoside natural product antibiotics target bacterial translocase MraY, involved in the lipid-linked cycle of peptidoglycan biosynthesis, and fungal chitin synthase. Biosynthetic studies on the nikkomycin, caprazamycin and pacidamycin/mureidomycin families are also reviewed.
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Affiliation(s)
- Michael Winn
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
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71
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Swoboda JG, Meredith TC, Campbell J, Brown S, Suzuki T, Bollenbach T, Malhowski AJ, Kishony R, Gilmore MS, Walker S. Discovery of a small molecule that blocks wall teichoic acid biosynthesis in Staphylococcus aureus. ACS Chem Biol 2009; 4:875-83. [PMID: 19689117 DOI: 10.1021/cb900151k] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Both Gram-positive and Gram-negative bacteria contain bactoprenol-dependent biosynthetic pathways expressing non-essential cell surface polysaccharides that function as virulence factors. Although these polymers are not required for bacterial viability in vitro, genes in many of the biosynthetic pathways are conditionally essential: they cannot be deleted except in strains incapable of initiating polymer synthesis. We report a cell-based, pathway-specific strategy to screen for small molecule inhibitors of conditionally essential enzymes. The screen identifies molecules that prevent the growth of a wildtype bacterial strain but do not affect the growth of a mutant strain incapable of initiating polymer synthesis. We have applied this approach to discover inhibitors of wall teichoic acid (WTA) biosynthesis in Staphylococcus aureus. WTAs are anionic cell surface polysaccharides required for host colonization that have been suggested as targets for new antimicrobials. We have identified a small molecule, 7-chloro-N,N-diethyl-3-(phenylsulfonyl)-[1,2,3]triazolo[1,5-a]quinolin-5-amine (1835F03), that inhibits the growth of a panel of S. aureus strains (MIC = 1-3 microg mL(-1)), including clinical methicillin-resistant S. aureus (MRSA) isolates. Using a combination of biochemistry and genetics, we have identified the molecular target as TarG, the transmembrane component of the ABC transporter that exports WTAs to the cell surface. We also show that preventing the completion of WTA biosynthesis once it has been initiated triggers growth arrest. The discovery of 1835F03 validates our chemical genetics strategy for identifying inhibitors of conditionally essential enzymes, and the strategy should be applicable to many other bactoprenol-dependent biosynthetic pathways in the pursuit of novel antibacterials and probes of bacterial stress responses.
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Affiliation(s)
- Jonathan G. Swoboda
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Timothy C. Meredith
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Jennifer Campbell
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Stephanie Brown
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Takashi Suzuki
- The Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, Massachusetts 02114
| | - Tobias Bollenbach
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Amy J. Malhowski
- Department of Medicine, Tufts Medical Center, Boston, Massachusetts 02111
| | - Roy Kishony
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Michael S. Gilmore
- The Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, Massachusetts 02114
| | - Suzanne Walker
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
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72
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Kaysser L, Lutsch L, Siebenberg S, Wemakor E, Kammerer B, Gust B. Identification and manipulation of the caprazamycin gene cluster lead to new simplified liponucleoside antibiotics and give insights into the biosynthetic pathway. J Biol Chem 2009; 284:14987-96. [PMID: 19351877 DOI: 10.1074/jbc.m901258200] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Caprazamycins are potent anti-mycobacterial liponucleoside antibiotics isolated from Streptomyces sp. MK730-62F2 and belong to the translocase I inhibitor family. Their complex structure is derived from 5'-(beta-O-aminoribosyl)-glycyluridine and comprises a unique N-methyldiazepanone ring. The biosynthetic gene cluster has been identified, cloned, and sequenced, representing the first gene cluster of a translocase I inhibitor. Sequence analysis revealed the presence of 23 open reading frames putatively involved in export, resistance, regulation, and biosynthesis of the caprazamycins. Heterologous expression of the gene cluster in Streptomyces coelicolor M512 led to the production of non-glycosylated bioactive caprazamycin derivatives. A set of gene deletions validated the boundaries of the cluster and inactivation of cpz21 resulted in the accumulation of novel simplified liponucleoside antibiotics that lack the 3-methylglutaryl moiety. Therefore, Cpz21 is assigned to act as an acyltransferase in caprazamycin biosynthesis. In vivo and in silico analysis of the caprazamycin biosynthetic gene cluster allows a first proposal of the biosynthetic pathway and provides insights into the biosynthesis of related uridyl-antibiotics.
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Affiliation(s)
- Leonard Kaysser
- Pharmazeutische Biologie, Pharmazeutisches Institut, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 8, 72076 Tübingen
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73
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High-throughput screening identifies novel inhibitors of the acetyltransferase activity of Escherichia coli GlmU. Antimicrob Agents Chemother 2009; 53:2306-11. [PMID: 19349513 DOI: 10.1128/aac.01572-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bifunctional GlmU protein catalyzes the formation of UDP-N-acetylglucosamine in a two-step reaction using the substrates glucosamine-1-phosphate, acetyl coenzyme A, and UTP. This metabolite is a common precursor to the synthesis of bacterial cell surface carbohydrate polymers, such as peptidoglycan, lipopolysaccharide, and wall teichoic acid that are involved in the maintenance of cell shape, permeability, and virulence. The C-terminal acetyltransferase domain of GlmU exhibits structural and mechanistic features unique to bacterial UDP-N-acetylglucosamine synthases, making it an excellent target for antibacterial design. In the work described here, we have developed an absorbance-based assay to screen diverse chemical libraries in high throughput for inhibitors to the acetyltransferase reaction of Escherichia coli GlmU. The primary screen of 50,000 drug-like small molecules identified 63 hits, 37 of which were specific to acetyltransferase activity of GlmU. Secondary screening and mode-of-inhibition studies identified potent inhibitors where compound binding within the acetyltransferase active site was requisite on the presence of glucosamine-1-phosphate and were competitive with the substrate acetyl coenzyme A. These molecules may represent novel chemical scaffolds for future antimicrobial drug discovery. In addition, this work outlines the utility of catalytic variants in targeting specific activities of bifunctional enzymes in high-throughput screens.
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74
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A-94964, a novel inhibitor of bacterial translocase I, produced by Streptomyces sp. SANK 60404. I. Taxonomy, isolation and biological activity. J Antibiot (Tokyo) 2009; 61:537-44. [PMID: 19160520 DOI: 10.1038/ja.2008.71] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Bacterial phospho-N-acetylmuramyl-pentapeptide translocase (translocase I: EC 2.7.8.13) is a key enzyme in peptidoglycan biosynthesis, and a known target of antibiotics. Here we report a novel nucleoside inhibitor against translocase I, A-94964, isolated from the culture broth of the strain Streptomyces sp. SANK 60404. A-94964 inhibited bacterial translocase I with IC50 value of 1.1 microg/ml, and showed antimicrobial activities against Staphylococcus aureus and Enterococcus faecalis with MIC of 100 and 50 microg/ml, respectively. A-94964 did not show cytotoxicity against mammalian cell lines.
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