1051
|
Rodrigues Coutinho AP, de Moraes LAB, Barata LES, de Souza AO. Effects of the antimycobacterial compound 2-phenoxy-1-phenylethanone on rat hepatocytes and formation of metabolites. PHARMACEUTICAL BIOLOGY 2012; 50:1317-1325. [PMID: 22857008 DOI: 10.3109/13880209.2012.674949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
CONTEXT Neolignans are usually dimers formed by oxidative coupling of allyl and propenyl phenols, and the neolignan analogue, 2-phenoxy-1-phenylethanone (LS-2) is a promising antimycobacterial compound showing very weak cytotoxicity in mammalian cells and lack of acute toxicity in murine models. OBJECTIVES To investigate the mechanism of action of LS-2 in rat hepatocytes by evaluating the activity levels of enzymes related to oxidation status and drug-metabolizing activity. MATERIALS AND METHODS Hepatocytes were treated with LS-2 from 0.05 up to 1 mM, for 24 and 48 h, and reduced glutathione (GSH), lipid peroxidation and cytochrome P450 enzyme (CYP450) activity were assayed. A homologous series of phenoxazone ethers were used as substrates to measure the enzymatic profile. The biotransformation of LS-2 was studied in hepatocytes by gas chromatography-mass spectrometry (GC-MS) for detection and analysis of possible metabolites. RESULTS Hepatocytes treated with LS-2 up to 1 mM for 24 or 48 h did not induce the formation of GSH and lipid peroxidation. O-Dealkylation activities of the isoenzymes CYP4501A1, CYP4501A2, CYP4502B1 and CYP4502B2 were also not detected in the hepatocytes treated with LS-2 for 24 or 48 h. DISCUSSION AND CONCLUSION The results indicate that LS-2 or its two detected metabolites, 2-phenoxy-1-phenylethanol and 2,4-(2-hydroxy-2-phenylethoxy)phenol, are not cytotoxic to rat hepatocytes. These compounds maintain a balance between the production of pro-oxidant agents and their respective antioxidant systems. The data show that enzymes related to oxidation status and drug-metabolizing activities are not involved in the mechanism of action of LS-2.
Collapse
|
1052
|
Affiliation(s)
- Gerard D Wright
- Department of Biochemistry and Biomedical Sciences, M.G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada.
| |
Collapse
|
1053
|
Bald D, Koul A. Advances and strategies in discovery of new antibacterials for combating metabolically resting bacteria. Drug Discov Today 2012; 18:250-5. [PMID: 23032727 DOI: 10.1016/j.drudis.2012.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 08/27/2012] [Accepted: 09/24/2012] [Indexed: 12/01/2022]
Abstract
Discovery of new antibacterial agents is crucial to counter the challenge of drug-resistant bacterial infections. In this review we discuss the issue of bacterial metabolic resting states, observed for a variety of pathogenic bacteria, which display low susceptibility for most antibacterials. We present examples of how bacterial metabolic states may be controlled, target pathways may be validated and screening on metabolically resting bacteria can be designed. A deeper understanding of bacterial metabolic states may provide valuable input for the design of efficient screening approaches in the discovery of new antibacterial agents.
Collapse
Affiliation(s)
- Dirk Bald
- Department of Molecular Cell Biology, Faculty of Earth- and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
| | | |
Collapse
|
1054
|
Synthetic biotechnology to study and engineer ribosomal bottromycin biosynthesis. ACTA ACUST UNITED AC 2012; 19:1278-87. [PMID: 23021914 DOI: 10.1016/j.chembiol.2012.08.013] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/03/2012] [Accepted: 08/09/2012] [Indexed: 12/23/2022]
Abstract
Bottromycins represent a promising class of antibiotics binding to the therapeutically unexploited A-site of the bacterial ribosome. By inhibiting translation they are active against clinically important pathogens, such as vancomycin-resistant Enterococci. Structurally, bottromycins are heavily modified peptides exhibiting various unusual biosynthetic features. To set the stage for compound modification and yield optimization, we identified the biosynthetic gene cluster, used synthetic biotechnology approaches to establish and improve heterologous production, and generated analogs by pathway genetic engineering. We unambiguously identified three radical SAM methyltransferase-encoding genes required for various methylations at unactivated carbons yielding tert-butyl valine, methyl-proline, and β-methyl-phenylalanine residues, plus a gene involved in aspartate methyl-ester formation. Evidence for the formation of the exo-thiazole unit and for a macrocyclodehydration mechanism leading to amidine ring formation is provided.
Collapse
|
1055
|
Bielecki P, Lukat P, Hüsecken K, Dötsch A, Steinmetz H, Hartmann RW, Müller R, Häussler S. Mutation in Elongation Factor G Confers Resistance to the Antibiotic Argyrin in the Opportunistic PathogenPseudomonas aeruginosa. Chembiochem 2012; 13:2339-45. [DOI: 10.1002/cbic.201200479] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Indexed: 11/12/2022]
|
1056
|
McAllister LA, Montgomery JI, Abramite JA, Reilly U, Brown MF, Chen JM, Barham RA, Che Y, Chung SW, Menard CA, Mitton-Fry M, Mullins LM, Noe MC, O'Donnell JP, Oliver RM, Penzien JB, Plummer M, Price LM, Shanmugasundaram V, Tomaras AP, Uccello DP. Heterocyclic methylsulfone hydroxamic acid LpxC inhibitors as Gram-negative antibacterial agents. Bioorg Med Chem Lett 2012; 22:6832-8. [PMID: 23046961 DOI: 10.1016/j.bmcl.2012.09.058] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/04/2012] [Accepted: 09/17/2012] [Indexed: 11/19/2022]
Abstract
The synthesis and antibacterial activity of heterocyclic methylsulfone hydroxamates is presented. Compounds in this series are potent inhibitors of the LpxC enzyme, a key enzyme involved in the production of lipopolysaccharide (LPS) found in the outer membrane of Gram-negative bacteria. SAR evaluation of compounds in this series revealed analogs with potent antibacterial activity against challenging Gram-negative species such as Pseudomonas aeruginosa and Klebsiella pneumoniae.
Collapse
Affiliation(s)
- Laura A McAllister
- Pfizer Worldwide Research and Development, 445 Eastern Point Road, Groton, CT 06340, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
1057
|
Aqeel Y, Iqbal J, Siddiqui R, Gilani AH, Khan NA. Anti-Acanthamoebic properties of resveratrol and demethoxycurcumin. Exp Parasitol 2012; 132:519-23. [PMID: 23010569 DOI: 10.1016/j.exppara.2012.09.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 04/16/2012] [Accepted: 09/12/2012] [Indexed: 12/24/2022]
Abstract
Acanthamoeba is an opportunist protist pathogen that is known to infect the cornea to produce eye keratitis and the central nervous system to produce fatal granulomatous encephalitis. Early diagnosis, followed by aggressive treatment using a combination of drugs is a prerequisite in successful treatment but even then, prognosis remains poor due to lack of effective drugs. The overall aim of the present study was to determine the anti-Acanthamoebic potential of natural compounds, resveratrol and curcuminoids. Adhesion and cytotoxicity assays were performed using primary human brain microvascular endothelial cells, which constitute the blood-brain barrier. Pre-exposure of organisms to 100 μg resveratrol and demethoxy curcumin prevented amoeba binding by 57% and 73%, respectively, while cytotoxicity of host cells was inhibited by 86%. In an assay for viability of amoebae in the absence of host cells, resveratrol and de-methoxy curcumin exhibited significant amoebicidal effects (23% and 25%, respectively) at 100 μg concentrations (P<0.01). Neither resveratrol nor demethoxycurcumin had any effect on the proteolytic activities of Acanthamoeba castellanii. Of both compounds, resveratrol is of most interest for further investigation, because of the selective toxicity of resveratrol on A. castellanii but not the human brain microvascular endothelial cells.
Collapse
Affiliation(s)
- Yousuf Aqeel
- Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan
| | | | | | | | | |
Collapse
|
1058
|
Dosselli R, Millioni R, Puricelli L, Tessari P, Arrigoni G, Franchin C, Segalla A, Teardo E, Reddi E. Molecular targets of antimicrobial photodynamic therapy identified by a proteomic approach. J Proteomics 2012; 77:329-43. [PMID: 23000218 DOI: 10.1016/j.jprot.2012.09.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 06/19/2012] [Accepted: 09/08/2012] [Indexed: 12/24/2022]
Abstract
Antimicrobial photodynamic therapy (PDT) is a promising tool to combat antibiotic-resistant bacterial infections. During PDT, bacteria are killed by reactive oxygen species generated by a visible light absorbing photosensitizer (PS). We used a classical proteomic approach that included two-dimensional gel electrophoresis and mass spectrometry analysis, to identify some proteins of Staphylococcus aureus that are damaged during PDT with the cationic PS meso-tetra-4-N-methyl pyridyl porphine (T4). Suspensions of S. aureus cells were incubated with selected T4 concentrations and irradiated with doses of blue light that reduced the survival to about 60% or 1%. Proteomics analyses of a membrane proteins enriched fraction revealed that these sub-lethal PDT treatments affected the expression of several functional classes of proteins, and that this damage is selective. Most of these proteins were found to be involved in metabolic activities, in oxidative stress response, in cell division and in the uptake of sugar. Subsequent analyses revealed that PDT treatments delayed the growth and considerably reduced the glucose consumption capacity of S. aureus cells. This investigation provides new insights towards the characterization of PDT induced damage and mechanism of bacterial killing using, for the first time, a proteomic approach.
Collapse
Affiliation(s)
- Ryan Dosselli
- Department of Biology, University of Padova, Via U. Bassi 58/B, 35128 Padova, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
1059
|
Hartkoorn RC, Sala C, Neres J, Pojer F, Magnet S, Mukherjee R, Uplekar S, Boy-Röttger S, Altmann KH, Cole ST. Towards a new tuberculosis drug: pyridomycin - nature's isoniazid. EMBO Mol Med 2012; 4:1032-42. [PMID: 22987724 PMCID: PMC3491834 DOI: 10.1002/emmm.201201689] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 07/26/2012] [Accepted: 07/30/2012] [Indexed: 01/27/2023] Open
Abstract
Tuberculosis, a global threat to public health, is becoming untreatable due to widespread drug resistance to frontline drugs such as the InhA-inhibitor isoniazid. Historically, by inhibiting highly vulnerable targets, natural products have been an important source of antibiotics including potent anti-tuberculosis agents. Here, we describe pyridomycin, a compound produced by Dactylosporangium fulvum with specific cidal activity against mycobacteria. By selecting pyridomycin-resistant mutants of Mycobacterium tuberculosis, whole-genome sequencing and genetic validation, we identified the NADH-dependent enoyl- (Acyl-Carrier-Protein) reductase InhA as the principal target and demonstrate that pyridomycin inhibits mycolic acid synthesis in M. tuberculosis. Furthermore, biochemical and structural studies show that pyridomycin inhibits InhA directly as a competitive inhibitor of the NADH-binding site, thereby identifying a new, druggable pocket in InhA. Importantly, the most frequently encountered isoniazid-resistant clinical isolates remain fully susceptible to pyridomycin, thus opening new avenues for drug development.
Collapse
Affiliation(s)
- Ruben C Hartkoorn
- Ecole Polytechnique Fédérale de Lausanne, Global Health Institute, Lausanne, Switzerland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
1060
|
Schiebel J, Chang A, Lu H, Baxter MV, Tonge PJ, Kisker C. Staphylococcus aureus FabI: inhibition, substrate recognition, and potential implications for in vivo essentiality. Structure 2012; 20:802-13. [PMID: 22579249 DOI: 10.1016/j.str.2012.03.013] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 03/01/2012] [Accepted: 03/03/2012] [Indexed: 12/11/2022]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infections constitute a serious health threat worldwide, and novel antibiotics are therefore urgently needed. The enoyl-ACP reductase (saFabI) is essential for the S. aureus fatty acid biosynthesis and, hence, serves as an attractive drug target. We have obtained a series of snapshots of this enzyme that provide a mechanistic picture of ligand and inhibitor binding, including a dimer-tetramer transition combined with extensive conformational changes. Significantly, our results reveal key differences in ligand binding and recognition compared to orthologous proteins. The remarkable observed protein flexibility rationalizes our finding that saFabI is capable of efficiently reducing branched-chain fatty acid precursors. Importantly, branched-chain fatty acids represent a major fraction of the S. aureus cell membrane and are crucial for its in vivo fitness. Our discovery thus addresses a long-standing controversy regarding the essentiality of the fatty acid biosynthesis pathway in S. aureus rationalizing saFabI as a drug target.
Collapse
Affiliation(s)
- Johannes Schiebel
- Rudolf Virchow Center for Experimental Biomedicine, Institute for Structural Biology, University of Würzburg, D-97080 Würzburg, Germany
| | | | | | | | | | | |
Collapse
|
1061
|
Shih HW, Chang YF, Li WJ, Meng FC, Huang CY, Ma C, Cheng TJR, Wong CH, Cheng WC. Effect of the Peptide Moiety of Lipid II on Bacterial Transglycosylase. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201204038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
1062
|
Shih HW, Chang YF, Li WJ, Meng FC, Huang CY, Ma C, Cheng TJR, Wong CH, Cheng WC. Effect of the peptide moiety of Lipid II on bacterial transglycosylase. Angew Chem Int Ed Engl 2012; 51:10123-6. [PMID: 22952114 DOI: 10.1002/anie.201204038] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Hao-Wei Shih
- Genomics Research Center, Academia Sinica, 128 Academia Road, Sec. 2, Taipei 115, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
1063
|
Halpenny GM, Heilman B, Mascharak PK. Nitric oxide (NO)-induced death of gram-negative bacteria from a light-controlled NO-releasing platform. Chem Biodivers 2012; 9:1829-39. [PMID: 22976973 PMCID: PMC3517148 DOI: 10.1002/cbdv.201100320] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A NO-delivery platform has been fabricated from polydimethylsiloxane (PDMS) and Pluronic(®) F127 gel that contains the light-sensitive NO donor, [Mn(PaPy(3))(NO)]ClO(4). The material was assembled layer-by-layer. First, a thin PDMS membrane was cast. It was then layered with cold 25% (w/v) Pluronic(®) F127 gel mixed with [Mn(PaPy(3))(NO)]ClO(4). Finally, it was covered with a thick layer (nearly impermeable to NO) of PDMS (=polydimethoxysiloxane) to allow release of NO only from the thinner side upon exposure to light. Light-induced NO release from this layered material has been confirmed via NO-specific electrode and by a modified soft Griess-agar assay. Incorporation of ca. 8 mg/g of [Mn(PaPy(3))(NO)]ClO(4) in the Pluronic gel layer affords a material that drastically reduces the microbial loads of Acinetobacter baumannii and Pseudomonas aeruginosa via the antibiotic effects of the photoreleased NO. Application of this flexible layered NO-donating composite as bandage material has been proposed.
Collapse
Affiliation(s)
| | | | - Pradip K. Mascharak
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95062
| |
Collapse
|
1064
|
de Lima Procópio RE, da Silva IR, Martins MK, de Azevedo JL, de Araújo JM. Antibiotics produced by Streptomyces. Braz J Infect Dis 2012; 16:466-71. [DOI: 10.1016/j.bjid.2012.08.014] [Citation(s) in RCA: 350] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/06/2012] [Indexed: 10/27/2022] Open
|
1065
|
Wang L, Pulk A, Wasserman MR, Feldman MB, Altman RB, Cate JHD, Blanchard SC. Allosteric control of the ribosome by small-molecule antibiotics. Nat Struct Mol Biol 2012; 19:957-63. [PMID: 22902368 PMCID: PMC3645490 DOI: 10.1038/nsmb.2360] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 07/13/2012] [Indexed: 12/15/2022]
Abstract
Protein synthesis is targeted by numerous, chemically distinct antibiotics that bind and inhibit key functional centers of the ribosome. Using single-molecule imaging and X-ray crystallography, we show that the aminoglycoside neomycin blocks aminoacyl-transfer RNA (aa-tRNA) selection and translocation as well as ribosome recycling by binding to helix 69 (H69) of 23S ribosomal RNA within the large subunit of the Escherichia coli ribosome. There, neomycin prevents the remodeling of intersubunit bridges that normally accompanies the process of subunit rotation to stabilize a partially rotated ribosome configuration in which peptidyl (P)-site tRNA is constrained in a previously unidentified hybrid position. Direct measurements show that this neomycin-stabilized intermediate is incompatible with the translation factor binding that is required for distinct protein synthesis reactions. These findings reveal the functional importance of reversible intersubunit rotation to the translation mechanism and shed new light on the allosteric control of ribosome functions by small-molecule antibiotics.
Collapse
MESH Headings
- Anti-Bacterial Agents/chemistry
- Anti-Bacterial Agents/pharmacology
- Crystallography, X-Ray
- Escherichia coli/chemistry
- Escherichia coli/drug effects
- Escherichia coli/metabolism
- Escherichia coli Proteins/metabolism
- Models, Molecular
- Neomycin/chemistry
- Neomycin/pharmacology
- Protein Biosynthesis/drug effects
- RNA, Bacterial/chemistry
- RNA, Bacterial/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/metabolism
- RNA, Transfer, Amino Acyl/metabolism
- Ribosome Subunits, Large, Bacterial/chemistry
- Ribosome Subunits, Large, Bacterial/drug effects
- Ribosome Subunits, Large, Bacterial/metabolism
- Ribosome Subunits, Small, Bacterial/chemistry
- Ribosome Subunits, Small, Bacterial/drug effects
- Ribosome Subunits, Small, Bacterial/metabolism
Collapse
Affiliation(s)
- Leyi Wang
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York, USA
| | | | | | | | | | | | | |
Collapse
|
1066
|
Doménech R, Martínez-Rodríguez S, Velázquez-Campoy A, Neira JL. Peptides as Inhibitors of the First Phosphorylation Step of the Streptomyces coelicolor Phosphoenolpyruvate: Sugar Phosphotransferase System. Biochemistry 2012; 51:7393-402. [DOI: 10.1021/bi3010494] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Rosa Doménech
- Instituto de Biología
Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
| | - Sergio Martínez-Rodríguez
- Departamento de Química-Física,
Bioquímica y Química Inorgánica, Universidad de Almería, Almería, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación
y Física de Sistemas Complejos (BIFI), Unidad Asociada IQFR-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Fundación ARAID, Diputación General de Aragón, Zaragoza,
Spain
- Departamento de Bioquímica
y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - José L. Neira
- Instituto de Biología
Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
- Instituto de Biocomputación
y Física de Sistemas Complejos (BIFI), Unidad Asociada IQFR-BIFI, Universidad de Zaragoza, Zaragoza, Spain
| |
Collapse
|
1067
|
Ballester PJ, Mangold M, Howard NI, Robinson RLM, Abell C, Blumberger J, Mitchell JBO. Hierarchical virtual screening for the discovery of new molecular scaffolds in antibacterial hit identification. J R Soc Interface 2012; 9:3196-207. [PMID: 22933186 PMCID: PMC3481598 DOI: 10.1098/rsif.2012.0569] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
One of the initial steps of modern drug discovery is the identification of small organic molecules able to inhibit a target macromolecule of therapeutic interest. A small proportion of these hits are further developed into lead compounds, which in turn may ultimately lead to a marketed drug. A commonly used screening protocol used for this task is high-throughput screening (HTS). However, the performance of HTS against antibacterial targets has generally been unsatisfactory, with high costs and low rates of hit identification. Here, we present a novel computational methodology that is able to identify a high proportion of structurally diverse inhibitors by searching unusually large molecular databases in a time-, cost- and resource-efficient manner. This virtual screening methodology was tested prospectively on two versions of an antibacterial target (type II dehydroquinase from Mycobacterium tuberculosis and Streptomyces coelicolor), for which HTS has not provided satisfactory results and consequently practically all known inhibitors are derivatives of the same core scaffold. Overall, our protocols identified 100 new inhibitors, with calculated Ki ranging from 4 to 250 μM (confirmed hit rates are 60% and 62% against each version of the target). Most importantly, over 50 new active molecular scaffolds were discovered that underscore the benefits that a wide application of prospectively validated in silico screening tools is likely to bring to antibacterial hit identification.
Collapse
Affiliation(s)
- Pedro J Ballester
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK.
| | | | | | | | | | | | | |
Collapse
|
1068
|
Nammalwar B, Bourne CR, Bunce RA, Wakeham N, Bourne PC, Ramnarayan K, Mylvaganam S, Berlin KD, Barrow EW, Barrow WW. Inhibition of bacterial dihydrofolate reductase by 6-alkyl-2,4-diaminopyrimidines. ChemMedChem 2012; 7:1974-82. [PMID: 22930550 DOI: 10.1002/cmdc.201200291] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Indexed: 11/09/2022]
Abstract
(±)-6-Alkyl-2,4-diaminopyrimidine-based inhibitors of bacterial dihydrofolate reductase (DHFR) have been prepared and evaluated for biological potency against Bacillus anthracis and Staphylococcus aureus. Biological studies revealed attenuated activity relative to earlier structures lacking substitution at C6 of the diaminopyrimidine moiety, though minimum inhibitory concentration (MIC) values are in the 0.125-8 μg mL(-1) range for both organisms. This effect was rationalized from three- dimensional X-ray structure studies that indicate the presence of a side pocket containing two water molecules adjacent to the main binding pocket. Because of the hydrophobic nature of the substitutions at C6, the main interactions are with protein residues Leu 20 and Leu 28. These interactions lead to a minor conformational change in the protein, which opens the pocket containing these water molecules such that it becomes continuous with the main binding pocket. These water molecules are reported to play a critical role in the catalytic reaction, highlighting a new area for inhibitor expansion within the limited architectural variation at the catalytic site of bacterial DHFR.
Collapse
Affiliation(s)
- Baskar Nammalwar
- Department of Chemistry, Oklahoma State University, Stillwater, OK 74078 (USA)
| | | | | | | | | | | | | | | | | | | |
Collapse
|
1069
|
LaBauve AE, Wargo MJ. Growth and laboratory maintenance of Pseudomonas aeruginosa. ACTA ACUST UNITED AC 2012; Chapter 6:Unit 6E.1.. [PMID: 22549165 DOI: 10.1002/9780471729259.mc06e01s25] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Pseudomonas aeruginosa is a common, free-living, Gram-negative bacterium that can cause significant disease as an opportunistic pathogen. Rapid growth, facile genetics, and a large suite of virulence-related phenotypes make P. aeruginosa a common model organism to study Gram-negative opportunistic pathogens and basic microbiology. This unit describes the basic laboratory growth and maintenance of P. aeruginosa.
Collapse
Affiliation(s)
- Annette E LaBauve
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, USA
| | | |
Collapse
|
1070
|
Abstract
A renewed interest in the development of new antimicrobial agents is urgently needed to combat the increasing number of antibiotic-resistant strains of pathogenic microorganisms. Actinomycetes continue to be the mainstream supplier of antibiotics used in industry. The likelihood of discovering a new compound with novel chemical structure can be increased with intensive efforts in isolating and screening of rare genera of microorganisms to include in natural-product-screening collections. An unexpected variety of rare actinomycetes is now being isolated worldwide from previously uninvestigated diverse natural habitats, using different selective isolation methods. These isolation efforts include methods to enhance growth (enrichment) of rare actinomycetes, and eliminate unwanted microorganisms (pretreatment). To speed up the strain isolation process, knowledge about the distribution of such unexploited groups of microorganisms must also be augmented. This is a summary of using these microorganisms as new potential biological resources, and a review of almost all of the selective isolation methods, including pretreatment and enrichment techniques that have been developed to date for the isolation of rare actinomycetes.
Collapse
Affiliation(s)
- Kavita Tiwari
- School of Biotechnology, Guru Gobind Singh Indraprastha University, Delhi, India
| | | |
Collapse
|
1071
|
Bremner JB, Keller PA, Pyne SG, Robertson MJ, Sakthivel K, Somphol K, Baylis D, Coates JA, Deadman J, Jeevarajah D, Rhodes DI. Binaphthyl-anchored antibacterial tripeptide derivatives with hydrophobic C-terminal amino acid variations. Beilstein J Org Chem 2012; 8:1265-70. [PMID: 23019457 PMCID: PMC3458747 DOI: 10.3762/bjoc.8.142] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 07/12/2012] [Indexed: 11/23/2022] Open
Abstract
The facile synthesis of seven new dicationic tripeptide benzyl ester derivatives, with hydrophobic group variations in the C-terminal amino acid component, is described. Moderate to good activity was seen against Gram-positive bacteria in vitro. One cyclohexyl-substituted compound 2c was tested more widely and showed good potency (MIC values ranging from 2-4 μg/mL) against antibiotic-resistant strains of Staphylococcus aureus and Enterococci (VRE, VSE), and against Staphylococcus epidermidis.
Collapse
Affiliation(s)
- John B Bremner
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
1072
|
Li P, Zhou C, Rayatpisheh S, Ye K, Poon YF, Hammond PT, Duan H, Chan-Park MB. Cationic peptidopolysaccharides show excellent broad-spectrum antimicrobial activities and high selectivity. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:4130-7. [PMID: 22434584 DOI: 10.1002/adma.201104186] [Citation(s) in RCA: 208] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 11/26/2011] [Indexed: 05/22/2023]
Affiliation(s)
- Peng Li
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
| | | | | | | | | | | | | | | |
Collapse
|
1073
|
Novel rapidly diversifiable antimicrobial RNA polymerase switch region inhibitors with confirmed mode of action in Haemophilus influenzae. J Bacteriol 2012; 194:5504-12. [PMID: 22843845 DOI: 10.1128/jb.01103-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A series of inhibitors with a squaramide core was synthesized following its discovery in a high-throughput screen for novel inhibitors of a transcription-coupled translation assay using Escherichia coli S30 extracts. The inhibitors were inactive when the plasmid substrate was replaced with mRNA, suggesting they interfered with transcription. This was confirmed by their inhibition of purified E. coli RNA polymerase. The series had antimicrobial activity against efflux-negative strains of E. coli and Haemophilus influenzae. Like rifampin, the squaramides preferentially inhibited synthesis of RNA and protein over fatty acids, peptidoglycan, and DNA. However, squaramide-resistant mutants were not cross-resistant to rifampin. Nine different mutations were found in parts of rpoB or rpoC that together encode the so-called switch region of RNA polymerase. This is the binding site of the natural antibiotics myxopyronin, corallopyronin, and ripostatin and the drug fidaxomicin. Computational modeling using the X-ray crystal structure of the myxopyronin-bound RNA polymerase of Thermus thermophilus suggests a binding mode of these inhibitors that is consistent with the resistance mutations. The squaramides are the first reported non-natural-product-related, rapidly diversifiable antibacterial inhibitors acting via the switch region of RNA polymerase.
Collapse
|
1074
|
Li SA, Lee WH, Zhang Y. Two bacterial infection models in tree shrew for evaluating the efficacy of antimicrobial agents. DONG WU XUE YAN JIU = ZOOLOGICAL RESEARCH 2012; 33:1-6. [PMID: 22345001 DOI: 10.3724/sp.j.1141.2012.01001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Animal models are essential for the development of new anti-infectious drugs. Although some bacterial infection models have been established in rodents, small primate models are rare. Here, we report on two bacterial infection models established in tree shrew (Tupaia belangeri chinensis). A burnt skin infection model was induced by dropping 5×10(6) CFU of Staphylococcus aureus on the surface of a wound after a third degree burn. This dose of S. aureus caused persistent infection for 7 days and obvious inflammatory response was observed 4 days after inoculation. A Dacron graft infection model, 2×10(6) CFU of Pseudomonas aeruginosa also caused persistent infection for 6 days, with large amounts of pus observed 3 days after inoculation. These models were used to evaluate the efficacy of levofloxacin (LEV) and cefoperazone (CPZ), which reduced the viable bacteria in skin to 4log10 and 5log10 CFU/100 mg tissue, respectively. The number of bacteria in graft was significantly reduced by 4log10 CFU/mL treatment compared to the untreated group (P<0.05). These results suggest that two bacterial infection models were successfully established in tree shrew using P. aeruginosa and S. aureus. In addition, tree shrew was susceptible to P. aeruginosa and S. aureus, thus making it an ideal bacterial infection animal model for the evaluation of new antimicrobials.
Collapse
Affiliation(s)
- Sheng-An Li
- Chinese Academy of Sciences, Kunming Yunnan, China
| | | | | |
Collapse
|
1075
|
Characterization of a rifampin-inactivating glycosyltransferase from a screen of environmental actinomycetes. Antimicrob Agents Chemother 2012; 56:5061-9. [PMID: 22802246 DOI: 10.1128/aac.01166-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Identifying and understanding the collection of all antibiotic resistance determinants presented in the global microbiota, the antibiotic resistome, provides insight into the evolution of antibiotic resistance and critical information for the development of future antimicrobials. The rifamycins are broad-spectrum antibiotics that target bacterial transcription by inhibition of RNA polymerase. Although mutational alteration of the drug target is the predominant mechanism of resistance to this family of antibiotics in the clinic, a number of diverse inactivation mechanisms have also been reported. In this report, we investigate a subset of environmental rifampin-resistant actinomycete isolates and identify a diverse collection of rifampin inactivation mechanisms. We describe a single isolate, WAC1438, capable of inactivating rifampin by glycosylation. A draft genome sequence of WAC1438 (most closely related to Streptomyces speibonae, according to a 16S rRNA gene comparison) was assembled, and the associated rifampin glycosyltransferase open reading frame, rgt1438, was identified. The role of rgt1438 in rifampin resistance was confirmed by its disruption in the bacterial chromosome, resulting in a loss of antibiotic inactivation and a 4-fold decrease in MIC. Interestingly, examination of the RNA polymerase β-subunit sequence of WAC1438 suggests that it harbors a resistant target and thus possesses dual mechanisms of rifamycin resistance. Using an in vitro assay with purified enzyme, Rgt1438 could inactivate a variety of rifamycin antibiotics with comparable steady-state kinetics constants. Our results identify rgt1438 as a rifampin resistance determinant from WAC1438 capable of inactivating an assortment of rifamycins, adding a new element to the rifampin resistome.
Collapse
|
1076
|
Kottakota SK, Evangelopoulos D, Alnimr A, Bhakta S, McHugh TD, Gray M, Groundwater PW, Marrs ECL, Perry JD, Spilling CD, Harburn JJ. Synthesis and biological evaluation of purpurealidin E-derived marine sponge metabolites: aplysamine-2, aplyzanzine A, and suberedamines A and B. JOURNAL OF NATURAL PRODUCTS 2012; 75:1090-101. [PMID: 22620987 DOI: 10.1021/np300102z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Five purpurealidin-derived marine secondary sponge metabolies have been synthesized through the carbodiimide coupling of an appropriate bromotyrosine unit. The structure elucidations have been confirmed through direct comparison with spectroscopic data of isolated natural products. Aplyzanzine A has been shown to be the most active product against a broad bacterial and fungal screen, demonstrating MIC values 2 to 4 times lower than the other metabolites in this study. Compounds 2, 3, 4a, and 5-7 exhibit a modest inhibition against slow growing mycobacteria (MIC 25-50 μg/mL), including Mycobacterium tuberculosis. iso-Anomoian A and suberedamine B showed antitumor activity in the NCI-DTP60 cell line screen at single-digit micromolar concentrations, with iso-anomoian A inhibiting 53 cell lines. These molecules present novel scaffolds for further optimization.
Collapse
Affiliation(s)
- Suresh K Kottakota
- Sunderland Pharmacy School, Department of Pharmacy, Health and Well-Being, University of Sunderland, Wharncliffe Street, Sunderland, SR1 3SD, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
1077
|
Evaluating the suitability of essential genes as targets for antibiotic screening assays using proteomics. Protein Cell 2012; 3:5-7. [PMID: 22246580 DOI: 10.1007/s13238-011-1135-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
|
1078
|
Violante IMP, Hamerski L, Garcez WS, Batista AL, Chang MR, Pott VJ, Garcez FR. Antimicrobial activity of some medicinal plants from the cerrado of the centralwestern region of Brazil. Braz J Microbiol 2012; 43:1302-8. [PMID: 24031956 PMCID: PMC3769025 DOI: 10.1590/s1517-83822012000400009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 01/17/2012] [Accepted: 06/07/2012] [Indexed: 11/21/2022] Open
Abstract
Ethanol extracts from six selected species from the Cerrado of the Central-Western region of Brazil, which are used in traditional medicine for the treatment of infectious diseases and other medical conditions, namely Erythroxylum suberosum St. Hil. (Erythroxylaceae), Hyptis crenata Pohl. ex Benth. (Lamiaceae), Roupala brasiliensis Klotz. (Proteaceae), Simarouba versicolor St. Hil. (Simaroubaceae), Guazuma ulmifolia Lam. (Sterculiaceae) and Protium heptaphyllum (Aubl.) March. (Burseraceae), as well as fractions resulting from partition of these crude extracts, were screened in vitro for their antifungal and antibacterial properties. The antimicrobial activities were assessed by the broth microdilution assay against six control fungal strains, Candida albicans, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis and Cryptococcus neoformans, and five control Gram-positive and negative bacterial strains, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. Toxicity of the extracts and fractions against Artemia salina was also evaluated in this work. All plants investigated showed antimicrobial properties against at least one microorganism and two species were also significantly toxic to brine shrimp larvae. The results tend to support the traditional use of these plants for the treatment of respiratory and gastrointestinal disorders and/or skin diseases, opening the possibility of finding new antimicrobial agents from these natural sources. Among the species investigated, Hyptis crenata, Erythroxylum suberosum and Roupala brasiliensis were considered the most promising candidates for developing of future bioactivity-guided phytochemical investigations.
Collapse
Affiliation(s)
- Ivana Maria Póvoa Violante
- Departamento de Química, Universidade Federal de Mato Grosso do Sul , Campo Grande, MS , Brasil ; Departamento de Farmácia, Universidade de Cuiabá , Cuiabá, MT , Brasil
| | | | | | | | | | | | | |
Collapse
|
1079
|
Abstract
Infectious diseases can be difficult to cure, especially if the pathogen forms a biofilm. After decades of extensive research into the morphology, physiology and genomics of biofilm formation, attention has recently been directed toward the analysis of the cellular metabolome in order to understand the transformation of a planktonic cell to a biofilm. Metabolomics can play an invaluable role in enhancing our understanding of the underlying biological processes related to the structure, formation and antibiotic resistance of biofilms. A systematic view of metabolic pathways or processes responsible for regulating this 'social structure' of microorganisms may provide critical insights into biofilm-related drug resistance and lead to novel treatments. This review will discuss the development of NMR-based metabolomics as a technology to study medically relevant biofilms. Recent advancements from case studies reviewed in this manuscript have shown the potential of metabolomics to shed light on numerous biological problems related to biofilms.
Collapse
Affiliation(s)
- Bo Zhang
- Department of Chemistry, University of Nebraska-Lincoln, 722 Hamilton Hall, Lincoln, NE 68588-0304, USA
| | - Robert Powers
- Department of Chemistry, University of Nebraska-Lincoln, 722 Hamilton Hall, Lincoln, NE 68588-0304, USA
| |
Collapse
|
1080
|
Koluman A, Dikici A. Antimicrobial resistance of emerging foodborne pathogens: status quo and global trends. Crit Rev Microbiol 2012; 39:57-69. [PMID: 22639875 DOI: 10.3109/1040841x.2012.691458] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Emerging foodborne pathogens are challenging subjects of food microbiology with their antibiotic resistance and their impact on public health. Campylobacter jejuni, Salmonella spp. and Verotoxigenic Escherichia coli (VTEC) are significant emerging food pathogens, globally. The decrease in supply and increase in demand lead developed countries to produce animal products with a higher efficiency. The massive production has caused the increase of the significant foodborne diseases. The strict control of food starting from farm to fork has been held by different regulations. Official measures have been applied to combat these pathogens. In 2005 EU declared that, an EU-wide ban on the use of antibiotics as growth promoters in animal feed would be applied on 1 January 2006. The ban is the final step in the phasing out of antibiotics used for non-medical purposes. It is a part of the Commission's strategy to tackle the emergence of bacteria and other microbes resistant to antibiotics, due to their overexploitation or misuse. As the awareness raises more countries banned application of antibiotics as growth promoter, but the resistance of the emerging foodborne pathogens do not represent decrease. Currently, the main concern of food safety is counter measures against resistant bugs.
Collapse
Affiliation(s)
- Ahmet Koluman
- Department of Microbiology, National Food Reference Laboratory, Fatih Sultan Mehmet Bulv., Tarim Kampusu, Yenimahalle, Ankara, Turkey.
| | | |
Collapse
|
1081
|
Gonzalez DJ, Xu Y, Yang YL, Esquenazi E, Liu WT, Edlund A, Duong T, Du L, Molnár I, Gerwick WH, Jensen PR, Fischbach M, Liaw CC, Straight P, Nizet V, Dorrestein PC. Observing the invisible through imaging mass spectrometry, a window into the metabolic exchange patterns of microbes. J Proteomics 2012; 75:5069-5076. [PMID: 22641157 DOI: 10.1016/j.jprot.2012.05.036] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 05/17/2012] [Accepted: 05/19/2012] [Indexed: 01/20/2023]
Abstract
Many microbes can be cultured as single-species communities. Often, these colonies are controlled and maintained via the secretion of metabolites. Such metabolites have been an invaluable resource for the discovery of therapeutics (e.g. penicillin, taxol, rapamycin, epothilone). In this article, written for a special issue on imaging mass spectrometry, we show that MALDI-imaging mass spectrometry can be adapted to observe, in a spatial manner, the metabolic exchange patterns of a diverse array of microbes, including thermophilic and mesophilic fungi, cyanobacteria, marine and terrestrial actinobacteria, and pathogenic bacteria. Dependent on media conditions, on average and based on manual analysis, we observed 11.3 molecules associated with each microbial IMS experiment, which was split nearly 50:50 between secreted and colony-associated molecules. The spatial distributions of these metabolic exchange factors are related to the biological and ecological functions of the organisms. This work establishes that MALDI-based IMS can be used as a general tool to study a diverse array of microbes. Furthermore the article forwards the notion of the IMS platform as a window to discover previously unreported molecules by monitoring the metabolic exchange patterns of organisms when grown on agar substrates.
Collapse
Affiliation(s)
- David J Gonzalez
- Department of Pediatrics, University of California, San Diego, United States
| | - Yuquan Xu
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, United States
| | - Yu-Liang Yang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, United States
| | - Eduardo Esquenazi
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, United States; Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, United States
| | - Wei-Ting Liu
- Department of Chemistry and Biochemistry, University of California, San Diego, United States
| | - Anna Edlund
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, United States
| | - Tram Duong
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, United States
| | - Liangcheng Du
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, United States
| | - István Molnár
- Natural Products Center, School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, United States
| | - William H Gerwick
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, United States
| | - Paul R Jensen
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, United States
| | - Michael Fischbach
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, United States
| | - Chih-Chuang Liaw
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung 804, Taiwan
| | - Paul Straight
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States
| | - Victor Nizet
- Department of Pediatrics, University of California, San Diego, United States
| | - Pieter C Dorrestein
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, United States; Department of Chemistry and Biochemistry, University of California, San Diego, United States; Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, United States.
| |
Collapse
|
1082
|
Novel antibiotics targeting respiratory ATP synthesis in Gram-positive pathogenic bacteria. Antimicrob Agents Chemother 2012; 56:4131-9. [PMID: 22615276 DOI: 10.1128/aac.00273-12] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Emergence of drug-resistant bacteria represents a high, unmet medical need, and discovery of new antibacterials acting on new bacterial targets is strongly needed. ATP synthase has been validated as an antibacterial target in Mycobacterium tuberculosis, where its activity can be specifically blocked by the diarylquinoline TMC207. However, potency of TMC207 is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify diarylquinolines with activity against key Gram-positive pathogens, significantly extending the antibacterial spectrum of the diarylquinoline class of drugs. These compounds inhibited growth of Staphylococcus aureus in planktonic state as well as in metabolically resting bacteria grown in a biofilm culture. Furthermore, time-kill experiments showed that the selected hits are rapidly bactericidal. Drug-resistant mutations were mapped to the ATP synthase enzyme, and biochemical analysis as well as drug-target interaction studies reveal ATP synthase as a target for these compounds. Moreover, knockdown of the ATP synthase expression strongly suppressed growth of S. aureus, revealing a crucial role of this target in bacterial growth and metabolism. Our data represent a proof of principle for using the diarylquinoline class of antibacterials in key Gram-positive pathogens. Our results suggest that broadening the antibacterial spectrum for this chemical class is possible without drifting off from the target. Development of the diarylquinolines class may represent a promising strategy for combating Gram-positive pathogens.
Collapse
|
1083
|
Rogers GB, Carroll MP, Bruce KD. Enhancing the utility of existing antibiotics by targeting bacterial behaviour? Br J Pharmacol 2012; 165:845-57. [PMID: 21864314 DOI: 10.1111/j.1476-5381.2011.01643.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The discovery of novel classes of antibiotics has slowed dramatically. This has occurred during a time when the appearance of resistant strains of bacteria has shown a substantial increase. Concern is therefore mounting over our ability to continue to treat infections in an effective manner using the antibiotics that are currently available. While ongoing efforts to discover new antibiotics are important, these must be coupled with strategies that aim to maintain as far as possible the spectrum of activity of existing antibiotics. In many instances, the resistance to antibiotics exhibited by bacteria in chronic infections is mediated not by direct resistance mechanisms, but by the adoption of modes of growth that confer reduced susceptibility. These include the formation of biofilms and the occurrence of subpopulations of 'persister' cells. As our understanding of these processes has increased, a number of new potential drug targets have been revealed. Here, advances in our ability to disrupt these systems that confer reduced susceptibility, and in turn increase the efficacy of antibiotic therapy, are discussed.
Collapse
Affiliation(s)
- Geraint B Rogers
- Molecular Microbiology Research Laboratory, Institute of Pharmaceutical Sciences, King's College London, London, UK.
| | | | | |
Collapse
|
1084
|
Gelin M, Poncet-Montange G, Assairi L, Morellato L, Huteau V, Dugué L, Dussurget O, Pochet S, Labesse G. Screening and in situ synthesis using crystals of a NAD kinase lead to a potent antistaphylococcal compound. Structure 2012; 20:1107-17. [PMID: 22608967 DOI: 10.1016/j.str.2012.03.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 03/09/2012] [Accepted: 03/30/2012] [Indexed: 11/18/2022]
Abstract
Making new ligands for a given protein by in situ ligation of building blocks (or fragments) is an attractive method. However, it suffers from inherent limitations, such as the limited number of available chemical reactions and the low information content of usual chemical library deconvolution. Here, we describe a focused screening of adenosine derivatives using X-ray crystallography. We discovered an unexpected and biocompatible chemical reactivity and have simultaneously identified the mode of binding of the resulting products. We observed that the NAD kinase from Listeria monocytogenes (LmNADK1) can promote amide formation between 5'-amino-5'-deoxyadenosine and carboxylic acid groups. This unexpected reactivity allowed us to bridge in situ two adenosine derivatives to fully occupy the active NAD site. This guided the design of a close analog showing micromolar inhibition of two human pathogenic NAD kinases and potent bactericidal activity against Staphylococcus aureus in vitro.
Collapse
Affiliation(s)
- Muriel Gelin
- Atelier de Bio- et Chimie Informatique Structurale, Centre de Biochimie Structurale, CNRS, UMR5048, Universités Montpellier 1 et 2, F-34090 Montpellier, France
| | | | | | | | | | | | | | | | | |
Collapse
|
1085
|
Bionda N, Stawikowski M, Stawikowska R, Cudic M, López-Vallejo F, Treitl D, Medina-Franco J, Cudic P. Effects of cyclic lipodepsipeptide structural modulation on stability, antibacterial activity, and human cell toxicity. ChemMedChem 2012; 7:871-82. [PMID: 22392790 PMCID: PMC3500847 DOI: 10.1002/cmdc.201200016] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 02/09/2012] [Indexed: 11/07/2022]
Abstract
Bacterial infections are becoming increasingly difficult to treat due to the development and spread of antibiotic resistance. Therefore, identifying novel antibacterial targets and new antibacterial agents capable of treating infections by drug-resistant bacteria is of vital importance. The structurally simple yet potent fusaricidin or LI-F class of natural products represents a particularly attractive source of candidates for the development of new antibacterial agents. We synthesized 18 fusaricidin/LI-F analogues and investigated the effects of structure modification on their conformation, serum stability, antibacterial activity, and toxicity toward human cells. Our findings show that substitution of an ester bond in depsipeptides with an amide bond may afford equally potent analogues with improved stability and greatly decreased cytotoxicity. The lower overall hydrophobicity/amphiphilicity of amide analogues in comparison with their parent depsipeptides, as indicated by HPLC retention times, may explain the dissociation of antibacterial activity and human cell cytotoxicity. These results indicate that amide analogues may have significant advantages over fusaricidin/LI-F natural products and their depsipeptide analogues as lead structures for the development of new antibacterial agents.
Collapse
Affiliation(s)
- Nina Bionda
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
- Department of Chemistry and BIochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 (USA)
| | - Maciej Stawikowski
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
| | - Roma Stawikowska
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
| | - Maré Cudic
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
| | - Fabian López-Vallejo
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
| | - Daniela Treitl
- Department of Chemistry and BIochemistry, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431 (USA)
| | - José Medina-Franco
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
| | - Predrag Cudic
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St. Lucie, Florida 34987 (USA), Fax: (+1) 772-345-3649
| |
Collapse
|
1086
|
JOYNER MICHELEL. MODELING THE DIFFERENCES IN THE DEVELOPMENT OF A NEW ANTIBIOTIC CLASS VERSUS THE DEVELOPMENT OF A NEXT GENERATION ANTIBIOTIC ON THE TOTAL RESISTANCE IN A HOSPITAL SETTING. J BIOL SYST 2012. [DOI: 10.1142/s0218339012500039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The increase in antibiotic resistance continues to pose a major public health risk leading to a more intense focus on ways to limit and even reduce this threat. One such effort is the push for twenty new classes of antibiotics by the year 2020. Most of the current antibiotics used today are derivations of antibiotics first introduced forty to fifty years ago. In this paper, we develop mathematical models to simulate the difference between implementing a next generation antibiotic versus a new class antibiotic within a hospital setting. Using these models, we simulate the short term and long term effects of using the new antibiotic to combat existing levels of antimicrobial resistance. In addition to analyzing the difference in antibiotic classes, we also analyze the effects of the method of administration of the new antibiotic. Simulations suggest a need in the long term for the development of new classes of antibiotics administered in a very structured, targeted manner.
Collapse
Affiliation(s)
- MICHELE L. JOYNER
- Department of Mathematics and Statistics, Institute for Quantitative Biology, East Tennesse State University, PO Box 70663, Johnson City, Tennessee 37614, United States
| |
Collapse
|
1087
|
Efficacy of OH-CATH30 and its analogs against drug-resistant bacteria in vitro and in mouse models. Antimicrob Agents Chemother 2012; 56:3309-17. [PMID: 22491685 DOI: 10.1128/aac.06304-11] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Antimicrobial peptides (AMPs) have been considered alternatives to conventional antibiotics for drug-resistant bacterial infections. However, their comparatively high toxicity toward eukaryotic cells and poor efficacy in vivo hamper their clinical application. OH-CATH30, a novel cathelicidin peptide deduced from the king cobra, possesses potent antibacterial activity in vitro. The objective of this study is to evaluate the efficacy of OH-CATH30 and its analog OH-CM6 against drug-resistant bacteria in vitro and in vivo. The MICs of OH-CATH30 and OH-CM6 ranged from 1.56 to 12.5 μg/ml against drug-resistant clinical isolates of several pathogenic species, including Escherichia coli, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus. The MICs of OH-CATH30 and OH-CM6 were slightly altered in the presence of 25% human serum. OH-CATH30 and OH-CM6 killed E. coli quickly (within 60 min) by disrupting the bacterial cytoplasmic membrane. Importantly, the 50% lethal doses (LD(50)) of OH-CATH30 and OH-CM6 in mice following intraperitoneal (i.p.) injection were 120 mg/kg of body weight and 100 mg/kg, respectively, and no death was observed at any dose up to 160 mg/kg following subcutaneous (s.c.) injection. Moreover, 10 mg/kg OH-CATH30 or OH-CM6 significantly decreased the bacterial counts as well as the inflammatory response in a mouse thigh infection model and rescued infected mice in a bacteremia model induced by drug-resistant E. coli. Taken together, our findings demonstrate that the natural cathelicidin peptide OH-CATH30 and its analogs exhibit relatively low toxicity and potent efficacy in mouse models, indicating that they may have therapeutic potential against the systemic infections caused by drug-resistant bacteria.
Collapse
|
1088
|
Schultsz C, Geerlings S. Plasmid-mediated resistance in Enterobacteriaceae: changing landscape and implications for therapy. Drugs 2012; 72:1-16. [PMID: 22191792 DOI: 10.2165/11597960-000000000-00000] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Antimicrobial resistance is increasing worldwide, and pathogenic microorganisms that are resistant to all available antimicrobial agents are increasingly reported. Emerging plasmid-encoded extended-spectrum β-lactamases (ESBLs) and carbapenemases are increasingly reported worldwide. Carbapenemase production encoded by genes located on mobile genetic elements is typically accompanied by genes encoding resistance to other drug classes, often but not necessarily located on the same mobile element. Multiple plasmid-mediated mechanisms of resistance against the fluoroquinolones and aminoglycosides have been described, and the combination of plasmid-mediated resistance with chromosomally encoded resistance mechanisms of multiple drug classes now results in strains that are resistant to all of the main classes of commonly used antimicrobial drugs. Clinical studies of antimicrobial therapy and outcome of patients infected with ESBL- or carbapenemase-producing strains of Enterobacteriaceae compared with patients infected with susceptible strains are limited in their design but suggest a worse outcome after infection with resistant strains. Alternative options for the treatment of infections caused by carbapenem-resistant strains of Enterobacteriaceae are limited. Current strategies include colistin, fosfomycin, tigecycline and temocillin. Although in vitro testing suggests strong activity for each of these drugs against a large proportion of carbapenem-resistant strains of Enterobacteriaceae, clinical evaluations do not provide strong evidence for equivalent or improved outcome. Oral treatment with fosfomycin tromethamine is effective against lower urinary tract infections (UTIs) caused by ESBL-producing Escherichia coli. Intravenous fosfomycin may be beneficial and safe for patients when used as part of a combination therapy in the management of severe infections caused by carbapenem-resistant Klebsiella pneumoniae. Tigecycline is only indicated for the treatment of complicated skin and skin structure infections and complicated intra-abdominal infections in Europe, and is also approved for treatment of community-acquired pneumonia in the US. Clearly, further research on the clinical and safety outcomes in the treatment of multidrug-resistant Enterobacteriaceae with these existing alternative drugs, and the development of new and unrelated drugs, are urgently warranted.
Collapse
Affiliation(s)
- Constance Schultsz
- Department of Global Health, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | | |
Collapse
|
1089
|
Munsch-Alatossava P, Gauchi JP, Chamlagain B, Alatossava T. Trends of Antibiotic Resistance in Mesophilic and Psychrotrophic Bacterial Populations during Cold Storage of Raw Milk. ISRN MICROBIOLOGY 2012; 2012:918208. [PMID: 23724333 PMCID: PMC3658802 DOI: 10.5402/2012/918208] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 12/25/2011] [Indexed: 11/23/2022]
Abstract
Psychrotrophic bacteria in raw milk are most well known for their spoilage potential and cause significant economic losses in the dairy industry. Despite their ability to produce several exoenzyme types at low temperatures, psychrotrophs that dominate the microflora at the time of spoilage are generally considered benign bacteria. It was recently reported that raw milk-spoiling Gram-negative-psychrotrophs frequently carried antibiotic resistance (AR) features. The present study evaluated AR to four antibiotics (ABs) (gentamicin, ceftazidime, levofloxacin, and trimethoprim-sulfamethoxazole) in mesophilic and psychrotrophic bacterial populations recovered from 18 raw milk samples, after four days storage at 4°C or 6°C. Robust analysis of variance and non parametric statistics (e.g., REGW and NPS) revealed that AR prevalence among psychrotrophs, for milk samples stored at 4°C, often equalled the initial levels and equalled or increased during the cold storage at 6°C, depending on the AB. The study performed at 4°C with an intermediate sampling point at day 2 suggested that (1) different psychrotrophic communities with varying AR levels dominate over time and (2) that AR (determined from relative amounts) was most prevalent, transiently, after 2-day storage in psychrotrophic or mesophilic populations, most importantly at a stage where total counts were below or around 10(5) CFU/mL, at levels at which the milk is acceptable for industrial dairy industrial processes.
Collapse
Affiliation(s)
- Patricia Munsch-Alatossava
- Division of Food Technology, Department of Food and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Jean-Pierre Gauchi
- Unité de Mathématiques et Informatique Appliquées (UR 341), Centre de Jouy en Josas, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas, France
| | - Bhawani Chamlagain
- Division of Food Technology, Department of Food and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| | - Tapani Alatossava
- Division of Food Technology, Department of Food and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
| |
Collapse
|
1090
|
Rapireddy S, Nhon L, Meehan RE, Franks J, Stolz DB, Tran D, Selsted ME, Ly DH. RTD-1mimic containing γPNA scaffold exhibits broad-spectrum antibacterial activities. J Am Chem Soc 2012; 134:4041-4. [PMID: 22332599 PMCID: PMC4848027 DOI: 10.1021/ja211867j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Macrocyclic peptides with multiple disulfide cross-linkages, such as those produced by plants and those found in nonhuman primates, as components of the innate immunity, hold great promise for molecular therapy because of their broad biological activities and high chemical, thermal, and enzymatic stability. However, for some, because of their intricate spatial arrangement and elaborate interstrand cross-linkages, they are difficult to prepare de novo in large quantities and high purity, due to the nonselective nature of disulfide-bond formation. We show that the disulfide bridges of RTD-1, a member of the θ-defensin subfamily, could be replaced with noncovalent Watson-Crick hydrogen bonds without significantly affecting its biological activities. The work provides a general strategy for engineering conformationally rigid, cyclic peptides without the need for disulfide-bond reinforcement.
Collapse
Affiliation(s)
- Srinivas Rapireddy
- Department of Chemistry and Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213
| | - Linda Nhon
- Department of Chemistry and Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213
| | - Robert E. Meehan
- Department of Chemistry and Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213
| | - Jonathan Franks
- Department of Cell Biology & Physiology, University of Pittsburgh School of Medicine, S362 BST, 3500 Terrace Street, Pittsburgh, PA 15261
| | - Donna Beer Stolz
- Department of Cell Biology & Physiology, University of Pittsburgh School of Medicine, S362 BST, 3500 Terrace Street, Pittsburgh, PA 15261
| | - Dat Tran
- Department of Pathology & Laboratory Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089
| | - Michael E. Selsted
- Department of Pathology & Laboratory Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089
| | - Danith H. Ly
- Department of Chemistry and Center for Nucleic Acids Science and Technology (CNAST), Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213
| |
Collapse
|
1091
|
Sun J, Hu J, Peng H, Shi J, Dong Z. Molecular and physiological characterization of fluoroquinolone resistance in relation to uropathogenicity among Escherichia coli isolates isolated from Wenyu River, China. CHEMOSPHERE 2012; 87:37-42. [PMID: 22182707 DOI: 10.1016/j.chemosphere.2011.11.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Revised: 11/15/2011] [Accepted: 11/22/2011] [Indexed: 05/31/2023]
Abstract
Increasing antibacterial resistance and pathogenicity in the environment is of growing concern due to its potential human risk. In the present study, 236 Escherichia coli isolates were collected from Wenyu River in China on drugless (48 isolates) and quinolone-containing plates (189 isolates). Their minimum inhibitory concentrations (MICs) were determined ranging from 0.125 μg mL(-1) to 128 μg mL(-1). Mutation points related to fluoroquinolone resistance were observed at S83 to L and D87 to N or Y in the GyrA subunit and S80 to R or I and E84 to G in the ParC subunit. Generally, MICs of LEV and GAT are dependent on the patterns of these mutation points. The profile with three mutation points was related to LEV-resistant E. coli isolates, and the (S83L, D87N+S80I) mutation profile was most prevalent (65.7%) in LEV-resistant isolates, while a large proportion of isolates, even those with three mutation points, were susceptive to GAT. The incidence of virulence factors in LEV-resistant isolates (44.7%, 59/132) was much higher than in nonresistant isolates (23.1%, 24/104) (χ(2)=11.925, 1° of freedom, p<0.001) indicating that fluoroquinolone-resistant E. coli would pose a potential risk. A similar distribution was also found in isolates resistant to GAT (χ(2)=7.843, 1° of freedom, p=0.0079).
Collapse
Affiliation(s)
- Jianxian Sun
- College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | | | | | | | | |
Collapse
|
1092
|
Eidem TM, Roux CM, Dunman PM. RNA decay: a novel therapeutic target in bacteria. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:443-54. [PMID: 22374855 DOI: 10.1002/wrna.1110] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The need for novel antibiotics is greater now than perhaps any time since the pre-antibiotic era. Indeed, the recent collapse of most pharmaceutical antibacterial groups, combined with the emergence of hypervirulent and pan-antibiotic-resistant bacteria have, in effect, created a 'perfect storm' that has severely compromised infection treatment options and led to dramatic increases in the incidence and severity of bacterial infections. To put simply, it is imperative that we develop new classes of antibiotics for the therapeutic intervention of bacterial infections. In that regard, RNA degradation is an essential biological process that has not been exploited for antibiotic development. Herein we discuss the factors that govern bacterial RNA degradation, highlight members of this machinery that represent attractive antimicrobial drug development targets and describe the use of high-throughput screening as a means of developing antimicrobials that target these enzymes. Such agents would represent first-in-class antibiotics that would be less apt to inactivation by currently encountered enzymatic antibiotic-resistance determinants.
Collapse
Affiliation(s)
- Tess M Eidem
- Department of Microbiology and Pathology, University of Nebraska Medical Center, Omaha, NE, USA
| | | | | |
Collapse
|
1093
|
Eibergen NR, Im I, Patel NY, Hergenrother PJ. Identification of a novel protein synthesis inhibitor active against gram-positive bacteria. Chembiochem 2012; 13:574-83, 490. [PMID: 22362659 DOI: 10.1002/cbic.201100727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Indexed: 11/12/2022]
Abstract
In an effort to identify novel antibacterial chemotypes, we performed a whole-cell screen for inhibitors of Staphylococcus aureus growth and pursued those compounds with previously uncharacterized antibacterial activity. This process resulted in the identification of a benzothiazolium salt, ABTZ-1, that displayed potent antibacterial activity against Gram-positive pathogens. Several clinically desirable qualities were demonstrated for ABTZ-1 including potent activity against multidrug-resistant clinical isolates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE), retention of this activity in human serum, and low hemolytic activity. The antibacterial activity of ABTZ-1 was attributed to its inhibition of bacterial translation, as this compound prevented the incorporation of [³⁵S]methionine into S. aureus proteins, and ABTZ-1-resistant strains were cross-resistant to known inhibitors of bacterial translation. ABTZ-1 represents a promising new class of antibacterial agents.
Collapse
Affiliation(s)
- Nora R Eibergen
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | | | | | | |
Collapse
|
1094
|
LiF Reduces MICs of Antibiotics against Clinical Isolates of Gram-Positive and Gram-Negative Bacteria. Int J Microbiol 2012; 2012:454065. [PMID: 22518143 PMCID: PMC3299231 DOI: 10.1155/2012/454065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/16/2011] [Indexed: 11/22/2022] Open
Abstract
Antibiotic resistance is an ever-growing problem yet the development of new antibiotics has slowed to a trickle, giving rise to the use of combination therapy to eradicate infections. The purpose of this study was to evaluate the combined inhibitory effect of lithium fluoride (LiF) and commonly used antimicrobials on the growth of the following bacteria: Enterococcus faecalis, Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, and Streptococcus pneumoniae. The in vitro activities of ceftazidime, sulfamethoxazole-trimethoprim, streptomycin, erythromycin, amoxicillin, and ciprofloxacin, doxycycline, alone or combined with LiF were performed by microdilution method. MICs were determined visually following 18–20 h of incubation at 37°C. We observed reduced MICs of antibiotics associated with LiF ranging from two-fold to sixteen-fold. The strongest decreases of MICs observed were for streptomycin and erythromycin associated with LiF against Acinetobacter baumannii and Streptococcus pneumoniae. An eight-fold reduction was recorded for streptomycin against S. pneumoniae whereas an eight-fold and a sixteen-fold reduction were obtained for erythromycin against A. baumannii and S. pneumoniae. This suggests that LiF exhibits a synergistic effect with a wide range of antibiotics and is indicative of its potential as an adjuvant in antibiotic therapy.
Collapse
|
1095
|
Ymele-Leki P, Cao S, Sharp J, Lambert KG, McAdam AJ, Husson RN, Tamayo G, Clardy J, Watnick PI. A high-throughput screen identifies a new natural product with broad-spectrum antibacterial activity. PLoS One 2012; 7:e31307. [PMID: 22359585 PMCID: PMC3281070 DOI: 10.1371/journal.pone.0031307] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 11/18/2022] Open
Abstract
Due to the inexorable invasion of our hospitals and communities by drug-resistant bacteria, there is a pressing need for novel antibacterial agents. Here we report the development of a sensitive and robust but low-tech and inexpensive high-throughput metabolic screen for novel antibiotics. This screen is based on a colorimetric assay of pH that identifies inhibitors of bacterial sugar fermentation. After validation of the method, we screened over 39,000 crude extracts derived from organisms that grow in the diverse ecosystems of Costa Rica and identified 49 with reproducible antibacterial effects. An extract from an endophytic fungus was further characterized, and this led to the discovery of three novel natural products. One of these, which we named mirandamycin, has broad-spectrum antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Vibrio cholerae, methicillin-resistant Staphylococcus aureus, and Mycobacterium tuberculosis. This demonstrates the power of simple high throughput screens for rapid identification of new antibacterial agents from environmental samples.
Collapse
Affiliation(s)
- Patrick Ymele-Leki
- Division of Infectious Diseases, Children's Hospital, Boston, Boston, Massachusetts, United States of America
| | | | | | | | | | | | | | | | | |
Collapse
|
1096
|
|
1097
|
Green OM, McKenzie AR, Shapiro AB, Otterbein L, Ni H, Patten A, Stokes S, Albert R, Kawatkar S, Breed J. Inhibitors of acetyltransferase domain of N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). Part 1: Hit to lead evaluation of a novel arylsulfonamide series. Bioorg Med Chem Lett 2012; 22:1510-9. [DOI: 10.1016/j.bmcl.2012.01.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 01/05/2012] [Accepted: 01/09/2012] [Indexed: 11/30/2022]
|
1098
|
Deciphering the magainin resistance process of Escherichia coli strains in light of the cytosolic proteome. Antimicrob Agents Chemother 2012; 56:1714-24. [PMID: 22290970 DOI: 10.1128/aac.05558-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Antimicrobial peptides (AMPs) are effective antibiotic agents commonly found in plants, animals, and microorganisms, and they have been suggested as the future of antimicrobial chemotherapies. It is vital to understand the molecular details that define the mechanism of action of resistance to AMPs for a rational planning of the next antibiotic generation and also to shed some light on the complex AMP mechanism of action. Here, the antibiotic resistance of Escherichia coli ATCC 8739 to magainin I was evaluated in the cytosolic subproteome. Magainin-resistant strains were selected after 10 subsequent spreads at subinhibitory concentrations of magainin I (37.5 mg · liter⁻¹), and their cytosolic proteomes were further compared to those of magainin-susceptible strains through two-dimensional electrophoresis analysis. As a result, 41 differentially expressed proteins were detected by in silico analysis and further identified by tandem mass spectrometry de novo sequencing. Functional categorization indicated an intense metabolic response mainly in energy and nitrogen uptake, stress response, amino acid conversion, and cell wall thickness. Indeed, data reported here show that resistance to cationic antimicrobial peptides possesses a greater molecular complexity than previously supposed, resulting in cell commitment to several metabolic pathways.
Collapse
|
1099
|
Lin FY, Zhang Y, Hensler M, Liu YL, Chow OA, Zhu W, Wang K, Pang R, Thienphrapa W, Nizet V, Oldfield E. Dual dehydrosqualene/squalene synthase inhibitors: leads for innate immune system-based therapeutics. ChemMedChem 2012; 7:561-4. [PMID: 22290830 DOI: 10.1002/cmdc.201100589] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Fu-Yang Lin
- Center for Biophysics & Computational Biology, University of Illinois at Urbana-Champaign, 607 South Mathews Avenue, Urbana, IL 61801, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
1100
|
Killer peptide: a novel paradigm of antimicrobial, antiviral and immunomodulatory auto-delivering drugs. Future Med Chem 2012; 3:1209-31. [PMID: 21806382 DOI: 10.4155/fmc.11.71] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The incidence of life-threatening viral and microbial infections has dramatically increased over recent decades. Despite significant developments in anti-infective chemotherapy, many issues have increasingly narrowed the therapeutic options, making it imperative to discover new effective molecules. Among them, small peptides are arousing great interest. This review will focus in particular on a killer peptide, engineered from an anti-idiotypic recombinant antibody that mimics the activity of a wide-spectrum antimicrobial yeast killer toxin targeting β-glucan cell-wall receptors. The in vitro and in vivo antimicrobial, antiviral and immunomodulatory activities of killer peptide and its ability to spontaneously and reversibly self-assemble and slowly release its active dimeric form over time will be discussed as a novel paradigm of targeted auto-delivering drugs.
Collapse
|