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Anthony Maxwell - One of the best experts on this subject based on the ideXlab platform.
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A Common Origin for the Bacterial Toxin-Antitoxin Systems parD and ccd, Suggested by Analyses of Toxin/ Target and Toxin/Antitoxin Interactions
2016Co-Authors: Andrew Smith. B. ¤a, Lesley A Mitchenall, Elizabeth Diago-navarro, Arjan Barendregt, Albert J. Heck, Anthony MaxwellAbstract:Bacterial toxin-antitoxin (TA) systems encode two proteins, a potent Inhibitor of cell proliferation (toxin) and its specific antidote (antitoxin). Structural data has revealed striking similarities between the two model TA toxins CcdB, a DNA Gyrase Inhibitor encoded by the ccd system of plasmid F, and Kid, a site-specific endoribonuclease encoded by the parD system of plasmid R1. While a common structural fold seemed at odds with the two clearly different modes of action of these toxins, the possibility of functional crosstalk between the parD and ccd systems, which would further point to their common evolutionary origin, has not been documented. Here, we show that the cleavage of RNA and the inhibition of protein synthesis by the Kid toxin, two activities that are specifically counteracted by its cognate Kis antitoxin, are altered, but not inhibited, by the CcdA antitoxin. In addition, Kis was able to inhibit the stimulation of DNA Gyrase-mediated cleavage of DNA by CcdB, albeit less efficiently than CcdA. We further show that physical interactions between the toxins and antitoxins of the different systems do occur and define the stoichiometry of the complexes formed. We found that CcdB did not degrade RNA nor did Kid have any reproducible effect on the tested DNA Gyrase activities, suggesting that these toxin
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SimC7 is a novel NAD(P)H-dependent ketoreductase essential for the antibiotic activity of the DNA Gyrase Inhibitor simocyclinone
Journal of Molecular Biology, 2015Co-Authors: Martin Schäfer, Anthony Maxwell, Stephen J. Hearnshaw, Gregory L. Challis, Barrie Wilkinson, Mark J. ButtnerAbstract:Simocyclinone D8 (SD8) is a potent DNA Gyrase Inhibitor produced by Streptomyces antibioticus Tu6040. The simocyclinone (sim) biosynthetic gene cluster has been sequenced and a hypothetical biosynthetic pathway has been proposed. The tetraene linker in SD8 was suggested to be the product of a modular type I polyketide synthase working in trans with two monofunctional enzymes. One of these monofunctional enzymes, SimC7, was proposed to supply a dehydratase activity missing from two modules of the polyketide synthase. In this study, we report the function of SimC7. We isolated the entire ~ 72-kb sim cluster on a single phage artificial chromosome clone and produced simocyclinone heterologously in a Streptomyces coelicolor strain engineered for improved antibiotic production. Deletion of simC7 resulted in the production of a novel simocyclinone, 7-oxo-SD8, which unexpectedly carried a normal tetraene linker but was altered in the angucyclinone moiety. We demonstrate that SimC7 is an NAD(P)H-dependent ketoreductase that catalyzes the conversion of 7-oxo-SD8 into SD8. 7-oxo-SD8 was essentially inactive as a DNA Gyrase Inhibitor, and the reduction of the keto group by SimC7 was shown to be crucial for high-affinity binding to the enzyme. Thus, SimC7 is an angucyclinone ketoreductase that is essential for the biological activity of simocyclinone.
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structural and biochemical analysis of the pentapeptide repeat protein efsqnr a potent dna Gyrase Inhibitor
Antimicrobial Agents and Chemotherapy, 2011Co-Authors: Subray S Hegde, Anthony Maxwell, M W Vetting, Lesley A Mitchenall, John S BlanchardAbstract:ABSTRACT The chromosomally encoded Qnr homolog protein from Enterococcus faecalis ( Efs Qnr), when expressed, confers to its host a decreased susceptibility to quinolones and consists mainly of tandem repeats, which is consistent with belonging to the pentapeptide repeat family of proteins (PRPs). Efs Qnr was cloned with an N-terminal 6× His tag and purified to homogeneity. Efs Qnr partially protected DNA Gyrase from fluoroquinolone inhibition at concentrations as low as 20 nM. Efs Qnr inhibited the ATP-dependent supercoiling activity of DNA Gyrase with a 50% Inhibitory concentration (IC 50 ) of 1.2 μM, while no significant inhibition of ATP-independent relaxation activity was observed. Efs Qnr was cytotoxic when overexpressed in Escherichia coli , resulting in the clumping of cells and a loss of viability. The X-ray crystal structure of Efs Qnr was determined to 1.6-A resolution. Efs Qnr exhibits the right-handed quadrilateral beta-helical fold typical of PRPs, with features more analogous to MfpA (mycobacterium fluoroquinolone resistance pentapeptide) than to the PRPs commonly found in cyanobacteria.
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structural and biochemical analysis of the pentapeptide repeat protein efsqnr a potent dna Gyrase Inhibitor
Antimicrobial Agents and Chemotherapy, 2011Co-Authors: Subray S Hegde, Anthony Maxwell, M W Vetting, Lesley A Mitchenall, John S BlanchardAbstract:The chromosomally encoded Qnr homolog protein from Enterococcus faecalis (EfsQnr), when expressed, confers to its host a decreased susceptibility to quinolones and consists mainly of tandem repeats, which is consistent with belonging to the pentapeptide repeat family of proteins (PRPs). EfsQnr was cloned with an N-terminal 6× His tag and purified to homogeneity. EfsQnr partially protected DNA Gyrase from fluoroquinolone inhibition at concentrations as low as 20 nM. EfsQnr inhibited the ATP-dependent supercoiling activity of DNA Gyrase with a 50% Inhibitory concentration (IC(50)) of 1.2 μM, while no significant inhibition of ATP-independent relaxation activity was observed. EfsQnr was cytotoxic when overexpressed in Escherichia coli, resulting in the clumping of cells and a loss of viability. The X-ray crystal structure of EfsQnr was determined to 1.6-A resolution. EfsQnr exhibits the right-handed quadrilateral beta-helical fold typical of PRPs, with features more analogous to MfpA (mycobacterium fluoroquinolone resistance pentapeptide) than to the PRPs commonly found in cyanobacteria.
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Coupling of the biosynthesis and export of the DNA Gyrase Inhibitor simocyclinone in Streptomyces antibioticus
Molecular Microbiology, 2009Co-Authors: Hans-peter Fiedler, Chris D. Den Hengst, Sang Kyun Ahn, Anthony Maxwell, Mark J. ButtnerAbstract:Because most antibiotics are potentially lethal to the producing organism, there must be mechanisms to ensure that the machinery responsible for export of the mature antibiotic is in place at the time of biosynthesis. Simocyclinone D8 is a potent DNA Gyrase Inhibitor produced by Streptomyces antibioticus Tu 6040. Within the simocyclinone biosynthetic cluster are two divergently transcribed genes, simR and simX, encoding proteins that resemble the TetR/TetA repressor-efflux pump pair that cause widespread resistance to clinically important tetracyclines. Engineered expression of simX from a strong, heterologous promoter conferred high level simocyclinone D8 resistance on Streptomyces lividans, showing that simX encodes a simocyclinone efflux pump. Transcription of simX is controlled by SimR, which directly represses the simX and simR promoters by binding to two operator sites in the simX-simR intergenic region. Simocyclinone D8 abolishes DNA binding by SimR, providing a mechanism that couples the biosynthesis of simocyclinone to its export. In addition, an intermediate in the biosynthetic pathway, simocyclinone C4, which is essentially inactive as a DNA Gyrase Inhibitor, also induces simX expression in vivo and relieves simX repression by SimR in vitro.
Michael D. Huband - One of the best experts on this subject based on the ideXlab platform.
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Determination of MIC Quality Control Ranges for the Novel Gyrase Inhibitor Zoliflodacin.
Journal of Clinical Microbiology, 2019Co-Authors: Alita A. Miller, Maria M. Traczewski, Michael D. Huband, Patricia A. Bradford, John P. MuellerAbstract:ABSTRACT This report describes the results of two different, multilaboratory quality control (QC) studies that were used to establish QC ranges for the novel Gyrase Inhibitor zoliflodacin against the ATCC strains recommended by the Clinical and Laboratory Standards Institute (CLSI). Following the completion of an eight-laboratory, CLSI document M23-defined tier 2 study, the agar dilution MIC QC range for zoliflodacin against the Neisseria gonorrhoeae QC strain ATCC 49226 was defined as 0.06 to 0.5 μg/ml and was approved by the CLSI Subcommittee on Antimicrobial Susceptibility Testing. This QC range will be used for in vitro susceptibility testing of zoliflodacin during phase 3 human clinical trials and surveillance studies, and eventually it will be implemented in clinical labs. In a separate study, broth microdilution MIC quality control ranges for zoliflodacin against additional QC strains were determined to be 0.12 to 0.5 μg/ml for Staphylococcus aureus ATCC 29213, 0.25 to 2 μg/ml for Enterococcus faecalis ATCC 29212, 1 to 4 μg/ml for Escherichia coli ATCC 25922, 0.12 to 0.5 μg/ml for Streptococcus pneumoniae ATCC 49619, and 0.12 to 1 μg/ml for Haemophilus influenzae ATCC 49247. These MIC QC ranges were also approved by CLSI for use in future in vitro susceptibility testing studies against organisms other than N. gonorrhoeae.
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in vitro activity of azd0914 a novel bacterial dna Gyrase topoisomerase iv Inhibitor against clinically relevant gram positive and fastidious gram negative pathogens
Antimicrobial Agents and Chemotherapy, 2015Co-Authors: Douglas J Biedenbach, Michael D. Huband, Meredith Hackel, Boudewijn L M De Jonge, Daniel F Sahm, Patricia A. BradfordAbstract:AZD0914, a new spiropyrimidinetrione bacterial DNA Gyrase Inhibitor with a novel mode of inhibition, has activity against bacterial species commonly cultured from patient infection specimens, including fluoroquinolone-resistant isolates. This study assessed the in vitro activity of AZD0914 against key Gram-positive and fastidious Gram-negative clinical isolates collected globally in 2013. AZD0914 demonstrated potent activity, with MIC90s for AZD0914 of 0.25 mg/liter against Staphylococcus aureus (n = 11,680), coagulase-negative staphylococci (n = 1,923), streptococci (n = 4,380), and Moraxella catarrhalis (n = 145), 0.5 mg/liter against Staphylococcus lugdunensis (n = 120) and Haemophilus influenzae (n = 352), 1 mg/liter against Enterococcus faecalis (n = 1,241), and 2 mg/liter against Haemophilus parainfluenzae (n = 70). The activity against Enterococcus faecium was more limited (MIC90, 8 mg/liter). The spectrum and potency of AZD0914 included fluoroquinolone-resistant isolates in each species group, including methicillin-resistant staphylococci, penicillin-resistant streptococci, vancomycin-resistant enterococci, β-lactamase-producing Haemophilus spp., and M. catarrhalis. Based on these in vitro findings, AZD0914 warrants further investigation for its utility against a variety of Gram-positive and fastidious Gram-negative bacterial species.
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Characterization of the Novel DNA Gyrase Inhibitor AZD0914: Low Resistance Potential and Lack of Cross-Resistance in Neisseria gonorrhoeae
Antimicrobial Agents and Chemotherapy, 2014Co-Authors: Richard A. Alm, Michael D. Huband, Sushmita D. Lahiri, Amy Kutschke, Linda G. Otterson, Robert E. Mclaughlin, James D. Whiteaker, Lisa A. Lewis, Humphrey GardnerAbstract:The unmet medical need for novel intervention strategies to treat Neisseria gonorrhoeae infections is significant and increasing, as rapidly emerging resistance in this pathogen is threatening to eliminate the currently available treatment options. AZD0914 is a novel bacterial Gyrase Inhibitor that possesses potent in vitro activities against isolates with high-level resistance to ciprofloxacin and extended-spectrum cephalosporins, and it is currently in clinical development for the treatment of N. gonorrhoeae infections. The propensity to develop resistance against AZD0914 was examined in N. gonorrhoeae and found to be extremely low, a finding supported by similar studies with Staphylococcus aureus. The genetic characterization of both first-step and second-step mutants that exhibited decreased susceptibilities to AZD0914 identified substitutions in the conserved GyrB TOPRIM domain, confirming DNA Gyrase as the primary target of AZD0914 and providing differentiation from fluoroquinolones. The analysis of available bacterial Gyrase and topoisomerase IV structures, including those bound to fluoroquinolone and nonfluoroquinolone Inhibitors, has allowed the rationalization of the lack of cross-resistance that AZD0914 shares with fluoroquinolones. Microbiological susceptibility data also indicate that the topoisomerase inhibition mechanisms are subtly different between N. gonorrhoeae and other bacterial species. Taken together, these data support the progression of AZD0914 as a novel treatment option for the oral treatment of N. gonorrhoeae infections.
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in vitro activity of azd0914 a novel dna Gyrase Inhibitor against chlamydia trachomatis and chlamydia pneumoniae
Antimicrobial Agents and Chemotherapy, 2014Co-Authors: Stephan Kohlhoff, Michael D. Huband, Margaret R HammerschlagAbstract:The in vitro activities of AZD0914, levofloxacin, azithromycin, and doxycycline against 10 isolates each of Chlamydia trachomatis and Chlamydia pneumoniae were tested. For AZD0914, the MIC90s for C. trachomatis and C. pneumoniae were 0.25 μg/ml (range, 0.06 to 0.5 μg/ml) and 1 μg/ml (range, 0.25 to 1 μg/ml), respectively, and the minimal bactericidal concentrations at which 90% of the isolates were killed (MBC90s) were 0.5 μg/ml for C. trachomatis (range, 0.125 to 1 μg/ml) and 2 μg/ml for C. pneumoniae (range, 0.5 to 2 μg/ml).
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high in vitro activity of the novel spiropyrimidinetrione azd0914 a dna Gyrase Inhibitor against multidrug resistant neisseria gonorrhoeae isolates suggests a new effective option for oral treatment of gonorrhea
Antimicrobial Agents and Chemotherapy, 2014Co-Authors: Susanne Jacobsson, Michael D. Huband, John P. Mueller, Daniel Golparian, Jorgen Skov Jensen, Makoto Ohnishi, Magnus UnemoAbstract:We evaluated the activity of the novel spiropyrimidinetrione AZD0914 (DNA Gyrase Inhibitor) against clinical gonococcal isolates and international reference strains (n = 250), including strains with diverse multidrug resistance and extensive drug resistance. The AZD0914 MICs were substantially lower than those of most other currently or previously recommended antimicrobials. AZD0914 should be further evaluated, including in vitro selection, in vivo emergence and mechanisms of resistance, pharmacokinetics/pharmacodynamics in humans, optimal dosing, and performance, in appropriate randomized and controlled clinical trials.
Stephane Cociancich - One of the best experts on this subject based on the ideXlab platform.
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what makes xanthomonas albilineans unique amongst xanthomonads
Frontiers in Plant Science, 2015Co-Authors: Isabelle Pieretti, Alexander Pesic, Daniel Petras, Monique Royer, Roderich D. Süssmuth, Stephane CociancichAbstract:Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. Compared to other species of Xanthomonas, X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy. Its genome, which has experienced significant erosion, has unique genomic features. It lacks two loci required for pathogenicity in other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis and the Hrp-T3SS (hypersensitive response and pathogenicity-type three secretion system) gene clusters. Instead, X. albilineans harbors in its genome an SPI-1 (Salmonella pathogenicity island-1) T3SS gene cluster usually found in animal pathogens. X. albilineans produces a potent DNA Gyrase Inhibitor called albicidin, which blocks chloroplast differentiation, resulting in the characteristic white foliar stripe symptoms. The antibacterial activity of albicidin also confers on X. albilineans a competitive advantage against rival bacteria during sugarcane colonization. Recent chemical studies have uncovered the unique structure of albicidin and allowed us to partially elucidate its fascinating biosynthesis apparatus, which involves an enigmatic hybrid PKS/NRPS (polyketide synthase/non-ribosomal peptide synthetase) machinery.
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The Gyrase Inhibitor albicidin consists of p-aminobenzoic acids and cyanoalanine
Nature Chemical Biology, 2015Co-Authors: Stephane Cociancich, Alexander Pesic, Daniel Petras, Julian Kretz, Vivien Schubert, Melanie Marguerettaz, Sandrine Duplan, Stefanie Uhlmann, Laura Vieweg, Julie NoellAbstract:Albicidin is a potent DNA Gyrase Inhibitor produced by the sugarcane pathogenic bacterium Xanthomonas albilineans. Here we report the elucidation of the hitherto unknown structure of albicidin, revealing a unique polyaromatic oligopeptide mainly composed of p-aminobenzoic acids. In vitro studies provide further insights into the biosynthetic machinery of albicidin. These findings will enable structural investigations on the inhibition mechanism of albicidin and its assessment as a highly effective antibacterial drug.
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full elucidation of the hitherto unknown structure of albicidin a potent antibiotic produced by xanthomonas albilineans
2015Co-Authors: Stephane Cociancich, Alexander Pesic, Daniel Petras, Julian Kretz, Vivien Schubert, Melanie Marguerettaz, Sandrine Duplan, Stefanie Uhlmann, Laura Vieweg, Julie NoellAbstract:Albicidin is a potent DNA Gyrase Inhibitor produced by the sugarcane pathogenic bacterium Xanthomonas albilineans. As such, this molecule blocks the differentiation of chloroplasts, resulting in appearance of narrow white stripes on sugarcane leaves that are characteristic of leaf scald disease. Albicidin targets the bacterial Gyrase by a mechanism that is different from the one of other DNA Gyrases Inhibitors like coumarins or quinolones [1]. It also exhibits antibacterial activity at nanomolar concentrations against Escherichia coli and to a lower extent against numerous Gram-negative and -positive human pathogenic bacteria [2].A decade of intense work was necessary to decipher albicidin's biosynthetic pathway and to elucidate its astonishing never-seen-before structure. Albicidin is produced by a hybrid PKS/NRPS (polyketide synthase/non ribosomal peptide synthetase) system. Such ribosome-independent systems consist of modular megasynthetases which operate in an assembly-line fashion to activate, modify and link mostly unusual aminoacid building blocks, finally resulting in complex bioactive peptide-like molecules. The structure of albicidin, which was predicted by former in silico sequence analyses of its PKS/NRPS gene cluster [3], was ascertained by means of mass spectrometry and nuclear magnetic resonance spectroscopy. We were able to demonstrate that albicidin exhibits a linear polyaromatic penta-peptidic structure containing the rare aminoacids para-aminobenzoate and cyanoalanine [4]. The determination of the structure of albicidin allowed the development of a protocol for the chemical synthesis of this complex molecule. Consequently, new research, such as structure-activity relationship studies, will now be possible [5].New insights into biosynthesis pathway and structural determination for albicidin will be presented. (Texte integral)
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heterologous production of albicidin a promising approach to overproducing and characterizing this potent Inhibitor of dna Gyrase
Antimicrobial Agents and Chemotherapy, 2007Co-Authors: Eric Vivien, Isabelle Pieretti, Stephane Cociancich, Delphine Pitorre, Dean W Gabriel, Philippe Rott, Monique RoyerAbstract:The phytotoxin and polyketide antibiotic albicidin produced by Xanthomonas albilineans is a highly potent DNA Gyrase Inhibitor. Low yields of albicidin production have slowed studies of its chemical structure. Heterologous expression of albicidin biosynthetic genes in X. axonopodis pv. vesicatoria resulted in a sixfold increase in albicidin production, offering promising strategies for engineering overproduction.
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heterologous production and characterization of albicidin a potent dna Gyrase Inhibitor
3rd European Conference on Prokaryotics Genomics (ProkaGENOMICS 2007) Göttingen Germany 07-10 October 2007, 2007Co-Authors: Stephane Cociancich, Isabelle Pieretti, Sandrine Duplan, Roderich D. Süssmuth, Philippe Rott, Kathrin Schneider, Gabriel Dean, Monique RoyerAbstract:Albicidin is a toxin and an antibiotic produced by the slow-growing bacterium Xanthomonas albilineans, the causal agent of sugarcane leaf scald. Albicidin is involved in the pathogenicity of X. albilineans and inhibits the replication of chloroplastic DNA. It also inhibits DNA replication in Escherichia coli at nanomolar concentrations, whereas mammalian cells are unaffected at 8 ?g/ml. Albicidin targets DNA Gyrase with features of inhibition that differ from those of other known antibiotics. It is synthesized by a unique hybrid polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) pathway that does not resemble any other pathway described to date. The antibiotic activity of albicidin against a wide range of gram-positive and gram-negative pathogenic bacteria (Enterobacter aerogenes, E. coli, Haemophilus influenzae, Klebsiella pneumoniae, Shigella sonnei, and Staphylococcus aureus) is of interest for the development of new antibacterial drugs. Low yields of albicidin production in slow-growing X. albilineans have slowed studies of its chemical structure and potential therapeutic applications. Therefore, we have developed a heterologous system for albicidin overproduction using a Xanthomonas axonopodis pv. vesicatoria strain transformed with two plasmids harbouring the complete albicidin biosynthetic gene set. A sixty-fold increase in albicidin production was obtained when compared to albicidin production by the native host, X. albilineans. Heterologous production of albicidin was confirmed by FTICR-MS (high resolving Fournier Transform Ion Cyclotron Resonance Mass Spectrometry). (Texte integral)
Brian S. J. Blagg - One of the best experts on this subject based on the ideXlab platform.
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engineering an antibiotic to fight cancer optimization of the novobiocin scaffold to produce anti proliferative agents
Journal of Medicinal Chemistry, 2011Co-Authors: Huiping Zhao, Alison C Donnelly, George Vielhauer, Jeffrey M Holzbeierlein, Bhaskar Reddy Kusuma, Gary E L Brandt, Douglas Brown, Roger A Rajewski, Mark S Cohen, Brian S. J. BlaggAbstract:Development of the DNA Gyrase Inhibitor, novobiocin, into a selective Hsp90 Inhibitor was accomplished through structural modifications to the amide side chain, coumarin ring, and sugar moiety. These species exhibit ∼700-fold improved anti-proliferative activity versus the natural product as evaluated by cellular efficacies against breast, colon, prostate, lung, and other cancer cell lines. Utilization of structure–activity relationships established for three novobiocin synthons produced optimized scaffolds, which manifest midnanomolar activity against a panel of cancer cell lines and serve as lead compounds that manifest their activities through Hsp90 inhibition.
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synthesis and evaluation of noviose replacements on novobiocin that manifest anti proliferative activity
ACS Medicinal Chemistry Letters, 2010Co-Authors: Huiping Zhao, Bhaskar Reddy Kusuma, Brian S. J. BlaggAbstract:Structural modifications to the coumarin core and benzamide side chain of novobiocin have successfully transformed the natural product from a selective DNA Gyrase Inhibitor into a potent Inhibitor of the Hsp90 C-terminus. However, no structure−activity relationship studies have been conducted on the noviose appendage, which represents the rate-limiting synthon in the preparation of analogues. Therefore, a series of sugar mimics and nonsugar derivatives were synthesized and evaluated to identify simplified compounds that exhibit Hsp90 inhibition. Evaluation against two breast cancer cell lines demonstrated that replacement of the stereochemical complex noviose with simplified alkyl amines increased antiproliferative activity, resulting in novobiocin analogues that manifest IC50 values in the midnanomolar range.
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the design synthesis and evaluation of coumarin ring derivatives of the novobiocin scaffold that exhibit antiproliferative activity
Journal of Organic Chemistry, 2008Co-Authors: Alison C Donnelly, Jared R Mays, Joseph A Burlison, John T Nelson, George Vielhauer, Jeffrey M Holzbeierlein, Brian S. J. BlaggAbstract:Novobiocin, a known DNA Gyrase Inhibitor, binds to a nucleotide-binding site located on the Hsp90 C-terminus and induces degradation of Hsp90-dependent client proteins at ∼700 μM in breast cancer cells (SKBr3). Although many analogues of novobiocin have been synthesized, it was only recently demonstrated that monomeric species exhibit antiproliferative activity against various cancer cell lines. To further refine the essential elements of the coumarin core, a series of modified coumarin derivatives was synthesized and evaluated to elucidate structure−activity relationships for novobiocin as an anticancer agent. Results obtained from these studies have produced novobiocin analogues that manifest low micromolar activity against several cancer cell lines.
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development of novobiocin analogues that manifest anti proliferative activity against several cancer cell lines
Journal of Organic Chemistry, 2008Co-Authors: Joseph A Burlison, George Vielhauer, Jeffrey M Holzbeierlein, Christopher Avila, Donna J Lubbers, Brian S. J. BlaggAbstract:Recent studies have shown that the DNA Gyrase Inhibitor, novobiocin, binds to a previously unrecognized ATP-binding site located at the C-terminus of Hsp90 and induces degradation of Hsp90-dependent client proteins at ∼700 μM. As a result of these studies, several analogues of the coumarin family of antibiotics have been reported and shown to exhibit increased Hsp90 Inhibitory activity; however, the monomeric species lacked the ability to manifest anti-proliferative activity against cancer cell lines at concentrations tested. In an effort to develop more efficacious compounds that produce growth Inhibitory activity against cancer cell lines, structure−activity relationships were investigated surrounding the prenylated benzamide side chain of the natural product. Results obtained from these studies have produced the first novobiocin analogues that manifest anti-proliferative activity against several cancer cell lines.
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novobiocin redesigning a dna Gyrase Inhibitor for selective inhibition of hsp90
Journal of the American Chemical Society, 2006Co-Authors: Joseph A Burlison, Len Neckers, Andrew B Smith, And Anthony Maxwell, Brian S. J. BlaggAbstract:Novobiocin is a member of the coumermycin family of antibiotics and is a well-established Inhibitor of DNA Gyrase. Recent studies have shown that novobiocin binds to a previously unrecognized ATP-binding site at the C-terminus of Hsp90 and induces degradation of Hsp90-dependent client proteins at ∼700 μM. In an effort to develop more efficacious Inhibitors of the C-terminal binding site, a library of novobiocin analogues was prepared and initial structure−activity relationships revealed. These data suggested that the 4-hydroxy moiety of the coumarin ring and the 3‘-carbamate of the noviose appendage were detrimental to Hsp90 Inhibitory activity. In an effort to confirm these findings, 4-deshydroxy novobiocin (DHN1) and 3‘-descarbamoyl-4-deshydroxynovobiocin (DHN2) were prepared and evaluated against Hsp90. Both compounds were significantly more potent than the natural product, and DHN2 proved to be more active than DHN1. In an effort to determine whether these moieties are important for DNA Gyrase inhibit...
Isabelle Pieretti - One of the best experts on this subject based on the ideXlab platform.
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what makes xanthomonas albilineans unique amongst xanthomonads
Frontiers in Plant Science, 2015Co-Authors: Isabelle Pieretti, Alexander Pesic, Daniel Petras, Monique Royer, Roderich D. Süssmuth, Stephane CociancichAbstract:Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. Compared to other species of Xanthomonas, X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy. Its genome, which has experienced significant erosion, has unique genomic features. It lacks two loci required for pathogenicity in other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis and the Hrp-T3SS (hypersensitive response and pathogenicity-type three secretion system) gene clusters. Instead, X. albilineans harbors in its genome an SPI-1 (Salmonella pathogenicity island-1) T3SS gene cluster usually found in animal pathogens. X. albilineans produces a potent DNA Gyrase Inhibitor called albicidin, which blocks chloroplast differentiation, resulting in the characteristic white foliar stripe symptoms. The antibacterial activity of albicidin also confers on X. albilineans a competitive advantage against rival bacteria during sugarcane colonization. Recent chemical studies have uncovered the unique structure of albicidin and allowed us to partially elucidate its fascinating biosynthesis apparatus, which involves an enigmatic hybrid PKS/NRPS (polyketide synthase/non-ribosomal peptide synthetase) machinery.
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genomic insights into strategies used by xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels
BMC Genomics, 2012Co-Authors: Isabelle Pieretti, Monique Royer, Valerie Barbe, Sebastien Carrere, Ralf Koebnik, Armelle Darrasse, Jerome Gouzy, Marieagnes Jacques, Arnaud Couloux, Emmanuelle LauberAbstract:Background Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA Gyrase Inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa—another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH), genomic features of two strains differing in pathogenicity.
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heterologous production of albicidin a promising approach to overproducing and characterizing this potent Inhibitor of dna Gyrase
Antimicrobial Agents and Chemotherapy, 2007Co-Authors: Eric Vivien, Isabelle Pieretti, Stephane Cociancich, Delphine Pitorre, Dean W Gabriel, Philippe Rott, Monique RoyerAbstract:The phytotoxin and polyketide antibiotic albicidin produced by Xanthomonas albilineans is a highly potent DNA Gyrase Inhibitor. Low yields of albicidin production have slowed studies of its chemical structure. Heterologous expression of albicidin biosynthetic genes in X. axonopodis pv. vesicatoria resulted in a sixfold increase in albicidin production, offering promising strategies for engineering overproduction.
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heterologous production and characterization of albicidin a potent dna Gyrase Inhibitor
3rd European Conference on Prokaryotics Genomics (ProkaGENOMICS 2007) Göttingen Germany 07-10 October 2007, 2007Co-Authors: Stephane Cociancich, Isabelle Pieretti, Sandrine Duplan, Roderich D. Süssmuth, Philippe Rott, Kathrin Schneider, Gabriel Dean, Monique RoyerAbstract:Albicidin is a toxin and an antibiotic produced by the slow-growing bacterium Xanthomonas albilineans, the causal agent of sugarcane leaf scald. Albicidin is involved in the pathogenicity of X. albilineans and inhibits the replication of chloroplastic DNA. It also inhibits DNA replication in Escherichia coli at nanomolar concentrations, whereas mammalian cells are unaffected at 8 ?g/ml. Albicidin targets DNA Gyrase with features of inhibition that differ from those of other known antibiotics. It is synthesized by a unique hybrid polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) pathway that does not resemble any other pathway described to date. The antibiotic activity of albicidin against a wide range of gram-positive and gram-negative pathogenic bacteria (Enterobacter aerogenes, E. coli, Haemophilus influenzae, Klebsiella pneumoniae, Shigella sonnei, and Staphylococcus aureus) is of interest for the development of new antibacterial drugs. Low yields of albicidin production in slow-growing X. albilineans have slowed studies of its chemical structure and potential therapeutic applications. Therefore, we have developed a heterologous system for albicidin overproduction using a Xanthomonas axonopodis pv. vesicatoria strain transformed with two plasmids harbouring the complete albicidin biosynthetic gene set. A sixty-fold increase in albicidin production was obtained when compared to albicidin production by the native host, X. albilineans. Heterologous production of albicidin was confirmed by FTICR-MS (high resolving Fournier Transform Ion Cyclotron Resonance Mass Spectrometry). (Texte integral)