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Structure-based pharmacophore modeling and virtual screening to identify novel inhibitors for anthrax lethal factor. Med Chem Res 2014. [DOI: 10.1007/s00044-014-0947-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Pandey P, Packiyaraj MS, Nigam H, Agarwal GS, Singh B, Patra MK. Antimicrobial properties of CuO nanorods and multi-armed nanoparticles against B. anthracis vegetative cells and endospores. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:789-800. [PMID: 24991516 PMCID: PMC4077429 DOI: 10.3762/bjnano.5.91] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 05/06/2014] [Indexed: 05/21/2023]
Abstract
Two different kinds of CuO nanoparticles (NPs) namely CuO nanorods (PS2) and multi-armed nanoparticles (P5) were synthesized by wet and electrochemical routes, respectively. Their structure, morphology, size and compositions were characterized by SEM, EDX and XRD. The NPs demonstrated strong bactericidal potential against Bacillus anthracis cells and endospores. PS2 killed 92.17% of 4.5 × 10(4) CFU/mL B. anthracis cells within 1 h at a dose of 1 mg/mL. Whereas P5 showed a higher efficacy by killing 99.92% of 7 × 10(5) CFU/mL B. anthracis cells within 30 min at a dose of 0.5 mg/mL and 99.6% of 1.25 × 10(4) CFU/mL B. anthracis cells within 5 min at a dose of 2 mg/mL. More than 99% of spores were killed within 8 h with 2 mg/mL PS2 in LB media.
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Affiliation(s)
- Pratibha Pandey
- Electron Microscopy Division Defence R&D Establishment, New Campus, Jhansi Road, Gwalior, India
| | - Merwyn S Packiyaraj
- Microbiology Division Defence R&D Establishment, New Campus, Jhansi Road, Gwalior, India
| | - Himangini Nigam
- Microbiology Division Defence R&D Establishment, New Campus, Jhansi Road, Gwalior, India
| | - Gauri S Agarwal
- Microbiology Division Defence R&D Establishment, New Campus, Jhansi Road, Gwalior, India
| | - Beer Singh
- Electron Microscopy Division Defence R&D Establishment, New Campus, Jhansi Road, Gwalior, India
- Protective Devices Division Defence R&D Establishment, New Campus, Jhansi Road, Gwalior, India
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Ganguly J, Low LY, Kamal N, Saile E, Forsberg LS, Gutierrez-Sanchez G, Hoffmaster AR, Liddington R, Quinn CP, Carlson RW, Kannenberg EL. The secondary cell wall polysaccharide of Bacillus anthracis provides the specific binding ligand for the C-terminal cell wall-binding domain of two phage endolysins, PlyL and PlyG. Glycobiology 2013; 23:820-32. [PMID: 23493680 DOI: 10.1093/glycob/cwt019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Endolysins are bacteriophage enzymes that lyse their bacterial host for phage progeny release. They commonly contain an N-terminal catalytic domain that hydrolyzes bacterial peptidoglycan (PG) and a C-terminal cell wall-binding domain (CBD) that confers enzyme localization to the PG substrate. Two endolysins, phage lysin L (PlyL) and phage lysin G (PlyG), are specific for Bacillus anthracis. To date, the cell wall ligands for their C-terminal CBD have not been identified. We recently described structures for a number of secondary cell wall polysaccharides (SCWPs) from B. anthracis and B. cereus strains. They are covalently bound to the PG and are comprised of a -ManNAc-GlcNAc-HexNAc- backbone with various galactosyl or glucosyl substitutions. Surface plasmon resonance (SPR) showed that the endolysins PlyL and PlyG bind to the SCWP from B. anthracis (SCWPBa) with high affinity (i.e. in the μM range with dissociation constants ranging from 0.81 × 10(-6) to 7.51 × 10(-6) M). In addition, the PlyL and PlyG SCWPBa binding sites reside with their C-terminal domains. The dissociation constants for the interactions of these endolysins and their derived C-terminal domains with the SCWPBa were in the range reported for other protein-carbohydrate interactions. Our findings show that the SCWPBa is the ligand that confers PlyL and PlyG lysin binding and localization to the PG. PlyL and PlyG also bound the SCWP from B. cereus G9241 with comparable affinities to SCWPBa. No detectable binding was found to the SCWPs from B. cereus ATCC (American Type Culture Collection) 10987 and ATCC 14579, thus demonstrating specificity of lysin binding to SCWPs.
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Affiliation(s)
- Jhuma Ganguly
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
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Dias GB, Gomes VM, Pereira UZ, Ribeiro SFF, Carvalho AO, Rodrigues R, Machado OLT, Fernandes KVS, Ferreira ATS, Perales J, Da Cunha M. Isolation, Characterization and Antifungal Activity of Proteinase Inhibitors from Capsicum chinense Jacq. Seeds. Protein J 2012; 32:15-26. [DOI: 10.1007/s10930-012-9456-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Leoff C, Saile E, Rauvolfova J, Quinn CP, Hoffmaster AR, Zhong W, Mehta AS, Boons GJ, Carlson RW, Kannenberg EL. Secondary cell wall polysaccharides of Bacillus anthracis are antigens that contain specific epitopes which cross-react with three pathogenic Bacillus cereus strains that caused severe disease, and other epitopes common to all the Bacillus cereus strains tested. Glycobiology 2009; 19:665-73. [PMID: 19270075 PMCID: PMC2682610 DOI: 10.1093/glycob/cwp036] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 02/27/2009] [Accepted: 02/27/2009] [Indexed: 11/12/2022] Open
Abstract
The immunoreactivities of hydrogen fluoride (HF)-released cell wall polysaccharides (HF-PSs) from selected Bacillus anthracis and Bacillus cereus strains were compared using antisera against live and killed B. anthracis spores. These antisera bound to the HF-PSs from B. anthracis and from three clinical B. cereus isolates (G9241, 03BB87, and 03BB102) obtained from cases of severe or fatal human pneumonia but did not bind to the HF-PSs from the closely related B. cereus ATCC 10987 or from B. cereus type strain ATCC 14579. Antiserum against a keyhole limpet hemocyanin conjugate of the B. anthracis HF-PS (HF-PS-KLH) also bound to HF-PSs and cell walls from B. anthracis and the three clinical B. cereus isolates, and B. anthracis spores. These results indicate that the B. anthracis HF-PS is an antigen in both B. anthracis cell walls and spores, and that it shares cross-reactive, and possibly pathogenicity-related, epitopes with three clinical B. cereus isolates that caused severe disease. The anti-HF-PS-KLH antiserum cross-reacted with the bovine serum albumin (BSA)-conjugates of all B. anthracis and all B. cereus HF-PSs tested, including those from nonclinical B. cereus ATCC 10987 and ATCC 14579 strains. Finally, the serum of vaccinated (anthrax vaccine adsorbed (AVA)) Rhesus macaques that survived inhalation anthrax contained IgG antibodies that bound the B. anthracis HF-PS-KLH conjugate. These data indicate that HF-PSs from the cell walls of the bacilli tested here are (i) antigens that contain (ii) a potentially virulence-associated carbohydrate antigen motif, and (iii) another antigenic determinant that is common to B. cereus strains.
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Affiliation(s)
| | | | - Jana Rauvolfova
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
| | - Conrad P Quinn
- Centers for Disease Control and Prevention, 1600 Clifton Rd., MS D-11, Atlanta, GA 30333, USA
| | - Alex R Hoffmaster
- Centers for Disease Control and Prevention, 1600 Clifton Rd., MS D-11, Atlanta, GA 30333, USA
| | - Wei Zhong
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
| | - Alok S Mehta
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
| | - Geert-Jan Boons
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
| | - Russell W Carlson
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
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Sequential B-cell epitopes of Bacillus anthracis lethal factor bind lethal toxin-neutralizing antibodies. Infect Immun 2008; 77:162-9. [PMID: 18981257 DOI: 10.1128/iai.00788-08] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bipartite anthrax lethal toxin (LeTx) consisting of protective antigen (PA) and lethal factor (LF) is a major virulence factor contributing to death from systemic Bacillus anthracis infection. The current vaccine elicits antibodies directed primarily to PA; however, in experimental settings serologic responses to LF can neutralize LeTx and contribute to protection against infection. The goals of the present study were to identify sequential B-cell epitopes of LF and to determine the capacity of these determinants to bind neutralizing antibodies. Sera of recombinant LF-immunized A/J mice exhibited high titers of immunoglobulin G anti-LF reactivity that neutralized LeTx in vitro 78 days after the final booster immunization and protected the mice from in vivo challenge with 3 50% lethal doses of LeTx. These sera bound multiple discontinuous epitopes, and there were major clusters of reactivity on native LF. Strikingly, all three neutralizing, LF-specific monoclonal antibodies tested bound specific peptide sequences that coincided with sequential epitopes identified in polyclonal antisera from recombinant LF-immunized mice. This study confirms that LF induces high-titer protective antibodies in vitro and in vivo. Moreover, the binding of short LF peptides by LF-specific neutralizing monoclonal antibodies suggests that generation of protective antibodies by peptide vaccination may be feasible for this antigen. This study paves the way for a more effective anthrax vaccine by identifying discontinuous peptide epitopes of LF.
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Aslan K, Zhang Y, Hibbs S, Baillie L, Previte MJR, Geddes CD. Microwave-accelerated metal-enhanced fluorescence: application to detection of genomic and exosporium anthrax DNA in <30 seconds. Analyst 2007; 132:1130-8. [PMID: 17955147 DOI: 10.1039/b707876e] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe the ultra-fast and sensitive detection of the gene encoding the protective antigen of Bacillus anthracis the causative agent of anthrax. Our approach employs a highly novel platform technology, Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF), which combines the use of Metal-Enhanced Fluorescence to enhance assay sensitivity and focused microwave heating to spatially and kinetically accelerate DNA hybridization. Genomic and exosporium target DNA of Bacillus anthracis spores was detected within a minute in the nanograms per microliter concentration range using low-power focused microwave heating. The MAMEF technology was able to distinguish between B. anthracis and B. cereus, a non-virulent close relative. We believe that this study has set the stage and indeed provides an opportunity for the ultra-fast and specific detection of B. anthracis spores with minimal pre-processing steps using a relatively simple but cost-effective technology that could minimize casualties in the event of another anthrax attack.
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Affiliation(s)
- Kadir Aslan
- Institute of Fluorescence, Laboratory for Advanced Medical Plasmonics, Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, MD 21201, USA
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Kedar GC, Brown-Driver V, Reyes DR, Hilgers MT, Stidham MA, Shaw KJ, Finn J, Haselbeck RJ. Evaluation of the metS and murB loci for antibiotic discovery using targeted antisense RNA expression analysis in Bacillus anthracis. Antimicrob Agents Chemother 2007; 51:1708-18. [PMID: 17339372 PMCID: PMC1855544 DOI: 10.1128/aac.01180-06] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The biowarfare-relevant bacterial pathogen Bacillus anthracis contains two paralogs each of the metS and murB genes, which encode the important antibiotic target functions methionyl-tRNA synthetase and UDP-N-acetylenolpyruvoylglucosamine reductase, respectively. Empirical screens were conducted to detect and characterize gene fragments of each of these four genes that could cause growth reduction of B. anthracis when inducibly expressed from a plasmid-borne promoter. Numerous such gene fragments that were overwhelmingly in the antisense orientation were identified for the metS1 and murB2 alleles, while no such orientation bias was seen for the metS2 and murB1 alleles. Gene replacement mutagenesis was used to confirm the essentiality of the metS1 and murB2 alleles, and the nonessentiality of the metS2 and murB1 alleles, for vegetative growth. Induced transcription of RNA from metS1 and murB2 antisense-oriented gene fragments resulted in specific reduction of mRNA of their cognate genes. Attenuation of MetS1 enzyme expression hypersensitized B. anthracis cells to a MetS-specific antimicrobial compound but not to other antibiotics that affect cell wall assembly, fatty acid biosynthesis, protein translation, or DNA replication. Antisense-dependent reduction of MurB2 enzyme expression caused hypersensitivity to beta-lactam antibiotics, a synergistic response that has also been noted for the MurA-specific antibiotic fosfomycin. These experiments form the basis of mode-of-action detection assays that can be used in the discovery of novel MetS- or MurB-specific antibiotic drugs that are effective against B. anthracis or other gram-positive bacterial pathogens.
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Affiliation(s)
- G C Kedar
- Trius Therapeutics Inc, San Diego, CA 92121, USA
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Schepetkin IA, Khlebnikov AI, Kirpotina LN, Quinn MT. Novel small-molecule inhibitors of anthrax lethal factor identified by high-throughput screening. J Med Chem 2006; 49:5232-44. [PMID: 16913712 DOI: 10.1021/jm0605132] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Anthrax lethal factor (LF) is a key virulence factor of anthrax lethal toxin. We screened a chemolibrary of 10,000 drug-like molecules for their ability to inhibit LF and identified 18 novel small molecules with potent LF inhibitory activity. Three additional LF inhibitors were identified through further structure-activity relationship (SAR) analysis. All 21 compounds inhibited LF with an IC50 range of 0.8 to 11 muM, utilizing mixed-mode competitive inhibition. An evaluation of inhibitory activity against a range of unrelated proteases showed relatively high specificity for LF. Furthermore, pharmacophore modeling of these compounds showed a high degree of similarity to the model published by Panchal et al. (Nat. Struct. Mol. Biol. 2004, 11, 67-72), indicating that the conformational features of these inhibitors are structurally compatible with the steric constraints of the substrate-binding pocket. These novel LF inhibitors and the structural scaffolds identified as important for inhibitory activity represent promising leads to pursue for further LF inhibitor development.
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Affiliation(s)
- Igor A Schepetkin
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana 59717, USA
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