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Mangano K, Marks J, Klepacki D, Saha CK, Atkinson GC, Vázquez-Laslop N, Mankin AS. Context-based sensing of orthosomycin antibiotics by the translating ribosome. Nat Chem Biol 2022; 18:1277-1286. [PMID: 36138139 DOI: 10.1038/s41589-022-01138-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 08/10/2022] [Indexed: 11/09/2022]
Abstract
Orthosomycin antibiotics inhibit protein synthesis by binding to the large ribosomal subunit in the tRNA accommodation corridor, which is traversed by incoming aminoacyl-tRNAs. Structural and biochemical studies suggested that orthosomycins block accommodation of any aminoacyl-tRNAs in the ribosomal A-site. However, the mode of action of orthosomycins in vivo remained unknown. Here, by carrying out genome-wide analysis of antibiotic action in bacterial cells, we discovered that orthosomycins primarily inhibit the ribosomes engaged in translation of specific amino acid sequences. Our results reveal that the predominant sites of orthosomycin-induced translation arrest are defined by the nature of the incoming aminoacyl-tRNA and likely by the identity of the two C-terminal amino acid residues of the nascent protein. We show that nature exploits this antibiotic-sensing mechanism for directing programmed ribosome stalling within the regulatory open reading frame, which may control expression of an orthosomycin-resistance gene in a variety of bacterial species.
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Affiliation(s)
- Kyle Mangano
- Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL, USA.,Amgen Research, Thousand Oaks, CA, USA
| | - James Marks
- Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL, USA.,National Institute of Arthritis and Musculoskeletal and Skin Disease, Bethesda, MD, USA
| | - Dorota Klepacki
- Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, IL, USA.,Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Chayan Kumar Saha
- Department of Experimental Medicine, Lund University, Lund, Sweden.,Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Gemma C Atkinson
- Department of Experimental Medicine, Lund University, Lund, Sweden
| | - Nora Vázquez-Laslop
- Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, IL, USA. .,Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL, USA.
| | - Alexander S Mankin
- Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, IL, USA. .,Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL, USA.
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2
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Yan S, Zeng M, Wang H, Zhang H. Micromonospora: A Prolific Source of Bioactive Secondary Metabolites with Therapeutic Potential. J Med Chem 2022; 65:8735-8771. [PMID: 35766919 DOI: 10.1021/acs.jmedchem.2c00626] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Micromonospora, one of the most important actinomycetes genera, is well-known as the treasure trove of bioactive secondary metabolites (SMs). Herein, together with an in-depth genomic analysis of the reported Micromonospora strains, all SMs from this genus are comprehensively summarized, containing structural features, bioactive properties, and mode of actions as well as their biosynthetic and chemical synthesis pathways. The perspective enables a detailed view of Micromonospora-derived SMs, which will enrich the chemical diversity of natural products and inspire new drug discovery in the pharmaceutical industry.
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Affiliation(s)
- Suqi Yan
- School of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Mingyuan Zeng
- School of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Hong Wang
- School of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Huawei Zhang
- School of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
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3
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Huang A, Luo X, Xu Z, Huang L, Wang X, Xie S, Pan Y, Fang S, Liu Z, Yuan Z, Hao H. Optimal Regimens and Clinical Breakpoint of Avilamycin Against Clostridium perfringens in Swine Based on PK-PD Study. Front Pharmacol 2022; 13:769539. [PMID: 35281904 PMCID: PMC8908370 DOI: 10.3389/fphar.2022.769539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/14/2022] [Indexed: 11/21/2022] Open
Abstract
Clostridium perfringens causes significant morbidity and mortality in swine worldwide. Avilamycin showed no cross resistance and good activity for treatment of C. perfringens. The aim of this study was to formulate optimal regimens of avilamycin treatment for C. perfringens infection based on the clinical breakpoint (CBP). The wild-type cutoff value (COWT) was defined as 0.25 μg/ml, which was developed based on the minimum inhibitory concentration (MIC) distributions of 120 C. perfringens isolates and calculated using ECOFFinder. Pharmacokinetics–pharmacodynamics (PK-PD) of avilamycin in ileal content were analyzed based on the high-performance liquid chromatography method and WinNonlin software to set up the target of PK/PD index (AUC0–24h/MIC)ex based on sigmoid Emax modeling. The PK parameters of AUC0–24h, Cmax, and Tmax in the intestinal tract were 428.62 ± 14.23 h μg/mL, 146.30 ± 13.41 μg/ml,, and 4 h, respectively. The target of (AUC0–24h/MIC)ex for bactericidal activity in intestinal content was 36.15 h. The PK-PD cutoff value (COPD) was defined as 8 μg/ml and calculated by Monte Carlo simulation. The dose regimen designed from the PK-PD study was 5.2 mg/kg mixed feeding and administrated for the treatment of C. perfringens infection. Five respective strains with different MICs were selected as the infection pathogens, and the clinical cutoff value was defined as 0.125 μg/ml based on the relationship between MIC and the possibility of cure (POC) following nonlinear regression analysis, CART, and “Window” approach. The CBP was set to be 0.25 μg/ml and selected by the integrated decision tree recommended by the Clinical Laboratory of Standard Institute. The formulation of the optimal regimens and CBP is good for clinical treatment and to control drug resistance.
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Affiliation(s)
- Anxiong Huang
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Xun Luo
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Zihui Xu
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Lingli Huang
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Xu Wang
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Shuyu Xie
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Yuanhu Pan
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Shiwei Fang
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Zhenli Liu
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Zonghui Yuan
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
| | - Haihong Hao
- National Reference Laboratory of Veterinary Drug Residues (HZAU) and MOA (Ministry of Agriculture) Key Laboratory for Detection of Veterinary Drug Residues, Wuhan, China.,MOA Laboratory for Risk Assessment of Quality and Safety of Livestock and Poultry Products, Wuhan, China
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4
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Schwaid AG, Cornella-Taracido I. Causes and Significance of Increased Compound Potency in Cellular or Physiological Contexts. J Med Chem 2017; 61:1767-1773. [DOI: 10.1021/acs.jmedchem.7b00762] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Adam G. Schwaid
- Merck & Co., Inc., Boston, Massachusetts 02115, United States
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5
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A brief history of antibiotics and select advances in their synthesis. J Antibiot (Tokyo) 2017; 71:153-184. [DOI: 10.1038/ja.2017.62] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/17/2017] [Accepted: 04/23/2017] [Indexed: 12/20/2022]
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6
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Waldman AJ, Ng TL, Wang P, Balskus EP. Heteroatom-Heteroatom Bond Formation in Natural Product Biosynthesis. Chem Rev 2017; 117:5784-5863. [PMID: 28375000 PMCID: PMC5534343 DOI: 10.1021/acs.chemrev.6b00621] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Natural products that contain functional groups with heteroatom-heteroatom linkages (X-X, where X = N, O, S, and P) are a small yet intriguing group of metabolites. The reactivity and diversity of these structural motifs has captured the interest of synthetic and biological chemists alike. Functional groups containing X-X bonds are found in all major classes of natural products and often impart significant biological activity. This review presents our current understanding of the biosynthetic logic and enzymatic chemistry involved in the construction of X-X bond containing functional groups within natural products. Elucidating and characterizing biosynthetic pathways that generate X-X bonds could both provide tools for biocatalysis and synthetic biology, as well as guide efforts to uncover new natural products containing these structural features.
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Affiliation(s)
- Abraham J. Waldman
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Tai L. Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Peng Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Emily P. Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
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7
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Purification, identification, and functional analysis of polysomes from the human pathogen Staphylococcus aureus. Methods 2017; 117:59-66. [DOI: 10.1016/j.ymeth.2016.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/21/2016] [Accepted: 10/06/2016] [Indexed: 12/14/2022] Open
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8
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Avilamycin and evernimicin induce structural changes in rProteins uL16 and CTC that enhance the inhibition of A-site tRNA binding. Proc Natl Acad Sci U S A 2016; 113:E6796-E6805. [PMID: 27791159 DOI: 10.1073/pnas.1614297113] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Two structurally unique ribosomal antibiotics belonging to the orthosomycin family, avilamycin and evernimicin, possess activity against Enterococci, Staphylococci, and Streptococci, and other Gram-positive bacteria. Here, we describe the high-resolution crystal structures of the eubacterial large ribosomal subunit in complex with them. Their extended binding sites span the A-tRNA entrance corridor, thus inhibiting protein biosynthesis by blocking the binding site of the A-tRNA elbow, a mechanism not shared with other known antibiotics. Along with using the ribosomal components that bind and discriminate the A-tRNA-namely, ribosomal RNA (rRNA) helices H89, H91, and ribosomal proteins (rProtein) uL16-these structures revealed novel interactions with domain 2 of the CTC protein, a feature typical to various Gram-positive bacteria. Furthermore, analysis of these structures explained how single nucleotide mutations and methylations in helices H89 and H91 confer resistance to orthosomycins and revealed the sequence variations in 23S rRNA nucleotides alongside the difference in the lengths of the eukaryotic and prokaryotic α1 helix of protein uL16 that play a key role in the selectivity of those drugs. The accurate interpretation of the crystal structures that could be performed beyond that recently reported in cryo-EM models provide structural insights that may be useful for the design of novel pathogen-specific antibiotics, and for improving the potency of orthosomycins. Because both drugs are extensively metabolized in vivo, their environmental toxicity is very low, thus placing them at the frontline of drugs with reduced ecological hazards.
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9
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Abstract
The sheer molecular scale of the ribosome is intimidating to the traditional drug designer. By analyzing the ribosome as a series of 12 key target sites, this review seeks to make the ribosome ligand design process more manageable. Analysis of recently evaluated ribosomal structures, particularly those with bound antibiotics, indicates where the ligand target sites are located. This review employs current research data to map antibiotic binding across the ribosome. A number of neighboring ligand-binding sites are often contiguous and can be combined. Ligands that bind in close proximity can be combined into hybrid structures. The different ways antibiotics disrupt ribosomal function are also discussed. Antibiotics tend to inhibit conformational changes that are essential to the ribosomal mechanism.
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10
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Removal of both zinc oxide and avilamycin from the post-weaning piglet diet: consequences for performance through to slaughter. ACTA ACUST UNITED AC 2016. [DOI: 10.1017/s1357729800053674] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractAvilamycin (AGP) and zinc oxide (ZnO) are both frequently included in the post-weaning piglet diet to enhance growth performance and prevent diarrhoea. This study investigated what effect removing these compounds from the post-weaning diet would have on the growth performance and faecal microbiota of weaned piglets. Fifty-two crossbred piglets (JSR Healthbred) were allocated, at weaning, to one of two dietary treatments on the basis of weight, litter origin and gender. The diets were (i) control (no supplemented ZnO or AGP); (ii) ZnO + AGP (supplemented with 3100 mg ZnO per kg food and 40 mg avilamycin per kg food). These diets were offered ad libitum for 20 days post weaning. Thereafter, the pigs received the same non-supplemented grower and finisher diets ad libitum. All piglets were individually weighed, and faecal samples were obtained from pre-selected piglets, at various time points throughout the trial period. Ten-fold serial dilutions of faecal material were cultured on specific media to enumerate aerobes, anaerobes, Lactobacillus spp. and Escherichia coli. ZnO + AGP supplementation enhanced weaned piglet average daily food intake (ADFI) (P < 0·001), average daily live-weight gain (ADG) (P < 0·001) and food conversion ratio (FCR) (P < 0·01) during the initial 20 days post weaning. Piglets previously supplemented with ZnO + AGP gained more weight per day during the non-supplemented grower phase (days 21 to 60) than their control counterparts (741·5 v. 672·5 g per pig per day) (P < 0·01). The bacteriological data showed that ZnO + AGP piglets had lower counts of anaerobic bacteria in their faeces than control piglets (P < 0·01). These findings indicate that dietary AGP + ZnO may enhance growth by reducing gastro-intestinal bacterial populations, and that their removal from the post-weaning diet will increase days to slaughter.
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11
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Structures of the orthosomycin antibiotics avilamycin and evernimicin in complex with the bacterial 70S ribosome. Proc Natl Acad Sci U S A 2016; 113:7527-32. [PMID: 27330110 DOI: 10.1073/pnas.1604790113] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ribosome is one of the major targets for therapeutic antibiotics; however, the rise in multidrug resistance is a growing threat to the utility of our current arsenal. The orthosomycin antibiotics evernimicin (EVN) and avilamycin (AVI) target the ribosome and do not display cross-resistance with any other classes of antibiotics, suggesting that they bind to a unique site on the ribosome and may therefore represent an avenue for development of new antimicrobial agents. Here we present cryo-EM structures of EVN and AVI in complex with the Escherichia coli ribosome at 3.6- to 3.9-Å resolution. The structures reveal that EVN and AVI bind to a single site on the large subunit that is distinct from other known antibiotic binding sites on the ribosome. Both antibiotics adopt an extended conformation spanning the minor grooves of helices 89 and 91 of the 23S rRNA and interacting with arginine residues of ribosomal protein L16. This binding site overlaps with the elbow region of A-site bound tRNA. Consistent with this finding, single-molecule FRET (smFRET) experiments show that both antibiotics interfere with late steps in the accommodation process, wherein aminoacyl-tRNA enters the peptidyltransferase center of the large ribosomal subunit. These data provide a structural and mechanistic rationale for how these antibiotics inhibit the elongation phase of protein synthesis.
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12
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Elshahawi SI, Shaaban KA, Kharel MK, Thorson JS. A comprehensive review of glycosylated bacterial natural products. Chem Soc Rev 2015; 44:7591-697. [PMID: 25735878 PMCID: PMC4560691 DOI: 10.1039/c4cs00426d] [Citation(s) in RCA: 299] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15 940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.
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Affiliation(s)
- Sherif I Elshahawi
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Khaled A Shaaban
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Madan K Kharel
- School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, Maryland, USA
| | - Jon S Thorson
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
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13
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Stokes JM, Davis JH, Mangat CS, Williamson JR, Brown ED. Discovery of a small molecule that inhibits bacterial ribosome biogenesis. eLife 2014; 3:e03574. [PMID: 25233066 PMCID: PMC4371806 DOI: 10.7554/elife.03574] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 09/17/2014] [Indexed: 11/29/2022] Open
Abstract
While small molecule inhibitors of the bacterial ribosome have been instrumental in
understanding protein translation, no such probes exist to study ribosome biogenesis.
We screened a diverse chemical collection that included previously approved drugs for
compounds that induced cold sensitive growth inhibition in the model bacterium
Escherichia coli. Among the most cold sensitive was lamotrigine,
an anticonvulsant drug. Lamotrigine treatment resulted in the rapid accumulation of
immature 30S and 50S ribosomal subunits at 15°C. Importantly, this was not the result
of translation inhibition, as lamotrigine was incapable of perturbing protein
synthesis in vivo or in vitro. Spontaneous suppressor mutations blocking lamotrigine
activity mapped solely to the poorly characterized domain II of translation
initiation factor IF2 and prevented the binding of lamotrigine to IF2 in vitro. This
work establishes lamotrigine as a widely available chemical probe of bacterial
ribosome biogenesis and suggests a role for E. coli IF2 in ribosome
assembly. DOI:http://dx.doi.org/10.7554/eLife.03574.001 Inside cells, molecular machines called ribosomes make proteins from instructions
that are provided by genes. The ribosomes themselves are made up of about 50 proteins
and three RNA molecules that need to be assembled like a 3-D jigsaw. In bacteria, a
group of proteins called ribosome biogenesis factors help to assemble these pieces
correctly. To study how a biological process works, scientists often look at what happens when a
component is missing or not working properly. However, this approach cannot be used
to study how ribosomes are made because stopping protein production entirely will
kill the cell. Another approach is to use chemicals to temporarily stop or slow down
a biological process, but researchers are yet to find a chemical that can do this for
ribosome assembly. To address this problem, Stokes et al. ‘screened’ 30,000 chemicals in an effort to
find one or more that could affect ribosome assembly in bacteria. The screen revealed
that a drug called lamotrigine—which is used to treat epilepsy and other conditions
in humans—could stop the assembly of ribosomes, but did not affect the production of
proteins by completed ribosomes. The experiments also suggest that initiation factor 2, a protein that is involved in
the production of other proteins, may also have a role in ribosome assembly. Another
recent study found that the equivalent of initiation factor 2 in yeast acts as a
quality control checkpoint during ribosome assembly, so the bacterial version may
also perform a similar role. It is also be possible that lamotrigine might be used to help develop a novel
mechanistic class of antibiotics. DOI:http://dx.doi.org/10.7554/eLife.03574.002
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Affiliation(s)
- Jonathan M Stokes
- Michael G DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Joseph H Davis
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Chand S Mangat
- Michael G DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - James R Williamson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, United States
| | - Eric D Brown
- Michael G DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
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14
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Abstract
Covering up to December 2013. Oligosaccharide natural products target a wide spectrum of biological processes including disruption of cell wall biosynthesis, interference of bacterial translation, and inhibition of human α-amylase. Correspondingly, oligosaccharides possess the potential for development as treatments of such diverse diseases as bacterial infections and type II diabetes. Despite their potent and selective activities and potential clinical relevance, isolated bioactive secondary metabolic oligosaccharides are less prevalent than other classes of natural products and their biosynthesis has received comparatively less attention. This review highlights the unique modes of action and biosynthesis of four classes of bioactive oligosaccharides: the orthosomycins, moenomycins, saccharomicins, and acarviostatins.
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Affiliation(s)
- Emilianne K McCranie
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, USA.
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15
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Determination of avilamycin as dichloroisoeverninic acid in poultry and porcine muscles by isotope dilution liquid chromatography-tandem mass spectrometry. Anal Bioanal Chem 2013; 405:8633-43. [PMID: 23975084 DOI: 10.1007/s00216-013-7262-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 07/04/2013] [Accepted: 07/15/2013] [Indexed: 10/26/2022]
Abstract
Avilamycin residue in food is regulated as its marker residue dichloroisoeverninic acid (DIA). An isotope dilution liquid chromatography-tandem mass spectrometry method is established for the accurate determination of DIA in animal muscles without any pre-extraction and preconcentration prior to alkaline hydrolysis. Optimization of the sample cleanup procedures such as liquid-liquid extraction and solid phase extraction was performed by fine-tuning several critical parameters to reduce the matrix effects. Quantification of DIA in edible muscle was accomplished by using matrix-matched calibration with dichloroisoeverninic acid-d6 as internal standard. The method was validated with DIA and avilamycin-fortified poultry and porcine muscles at three different levels (25, 50, and 100 μg/kg). Conversion of avilamycin to DIA by alkaline hydrolysis was ≥92%. The recoveries of DIA in both muscles at three fortification levels ranged from 94 to 106% and RSDs were ≤11% in all cases. The estimated limit of detection values in poultry and porcine muscles were 2.7 and 0.7 μg/kg, respectively. The estimated limit of quantitation values in poultry and porcine muscles were 8.3 and 2.4 μg/kg, respectively. This method is suitable for routine monitoring of avilamycin residue in food safety surveillance programs.
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16
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Schitter G, Wrodnigg TM. Update on carbohydrate-containing antibacterial agents. Expert Opin Drug Discov 2013; 4:315-56. [PMID: 23489128 DOI: 10.1517/17460440902778725] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Since the first known use of antibiotics > 2,500 years ago, a research field with immense importance for the welfare of mankind has been developed. After a decrease in interest in this topic by the end of the 20th century the occurrence of (poly-)resistant strains of bacteria induced a revival of antibiotics research. Health systems have been seeking viable and reliable solutions to this dangerous and expansive threat. OBJECTIVE This review will focus on carbohydrate-containing antibiotics and will give an outline of recently published novel isolated, semisynthetic as well as synthetic structures, their mechanism of action, if known, and the strategies for the design of compounds with potential by improved antibacterial properties. METHODS The literature between 2000 and 2008 was screened with main focus on recent examples of novel structures and strategies for the lead finding of exclusively antibacterial agents. RESULTS/CONCLUSION With the explanation of the role of the carbohydrate moieties in the respective antibacterial agents together with better synthetic strategies in carbohydrate chemistry as well as improvements in assay development for high throughput screening methods, carbohydrate-containing antibiotics can be used for the finding of potential drug leads that contribute to the fight against infections and diseases caused by (resistant) bacterial pathogens.
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Affiliation(s)
- Georg Schitter
- Technical University Graz, Institute of Organic Chemistry, Univ.-Doz. TMW, Dip.-Ing. GS, Glycogroup, A-8010 Graz, Austria +43 316 873 8744 ; +43 316 873 8740 ;
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17
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Mikolajka A, Liu H, Chen Y, Starosta AL, Márquez V, Ivanova M, Cooperman BS, Wilson DN. Differential effects of thiopeptide and orthosomycin antibiotics on translational GTPases. ACTA ACUST UNITED AC 2011; 18:589-600. [PMID: 21609840 DOI: 10.1016/j.chembiol.2011.03.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 03/07/2011] [Accepted: 03/14/2011] [Indexed: 11/18/2022]
Abstract
The ribosome is a major target in the bacterial cell for antibiotics. Here, we dissect the effects that the thiopeptide antibiotics thiostrepton (ThS) and micrococcin (MiC) as well as the orthosomycin antibiotic evernimicin (Evn) have on translational GTPases. We demonstrate that, like ThS, MiC is a translocation inhibitor, and that the activation by MiC of the ribosome-dependent GTPase activity of EF-G is dependent on the presence of the ribosomal proteins L7/L12 as well as the G' subdomain of EF-G. In contrast, Evn does not inhibit translocation but is a potent inhibitor of back-translocation as well as IF2-dependent 70S-initiation complex formation. Collectively, these results shed insight not only into fundamental aspects of translation but also into the unappreciated specificities of these classes of translational inhibitors.
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18
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Affiliation(s)
- Jonas J. Forsman
- Laboratory of Organic Chemistry, Åbo Akademi University, FI-20500 Åbo, Finland
| | - Reko Leino
- Laboratory of Organic Chemistry, Åbo Akademi University, FI-20500 Åbo, Finland
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19
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Vey JL, Al-Mestarihi A, Hu Y, Funk MA, Bachmann BO, Iverson TM. Structure and mechanism of ORF36, an amino sugar oxidizing enzyme in everninomicin biosynthesis . Biochemistry 2010; 49:9306-17. [PMID: 20866105 DOI: 10.1021/bi101336u] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Everninomicin is a highly modified octasaccharide that belongs to the orthosomycin family of antibiotics and possesses potent Gram-positive antibiotic activity, including broad-spectrum efficacy against multidrug resistant enterococci and Staphylococcus aureus. Among its distinctive structural features is a nitro sugar, l-evernitrose, analogues of which decorate a variety of natural products. Recently, we identified a nitrososynthase enzyme encoded by orf36 from Micromonospora carbonacea var. africana that mediates the flavin-dependent double oxidation of synthetically generated thymidine diphosphate (TDP)-l-epi-vancosamine to the corresponding nitroso sugar. Herein, we utilize a five-enzyme in vitro pathway both to verify that ORF36 catalyzes oxidation of biogenic TDP-l-epi-vancosamine and to determine whether ORF36 exhibits catalytic competence for any of its biosynthetic progenitors, which are candidate substrates for nitrososynthases in vivo. Progenitors solely undergo single-oxidation reactions and terminate in the hydroxylamine oxidation state. Performing the in vitro reactions in the presence of (18)O(2) establishes that molecular oxygen, rather than oxygen from water, is incorporated into ORF36-generated intermediates and products and identifies an off-pathway product that correlates with the oxidation product of a progenitor substrate. The 3.15 Å resolution X-ray crystal structure of ORF36 reveals a tetrameric enzyme that shares a fold with acyl-CoA dehydrogenases and class D flavin-containing monooxygenases, including the nitrososynthase KijD3. However, ORF36 and KijD3 have unusually open active sites in comparison to these related enzymes. Taken together, these studies map substrate determinants and allow the proposal of a minimal monooxygenase mechanism for amino sugar oxidation by ORF36.
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Affiliation(s)
- Jessica L Vey
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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20
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Aarestrup FM, Tvede M. Susceptibility of Clostridium difficile toward antimicrobial agents used as feed additives for food animals. Microb Drug Resist 2010; 17:125-7. [PMID: 20950192 DOI: 10.1089/mdr.2010.0068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A total of 65 toxigenic Clostridium difficile strains isolated from patients with antibiotic-associated diarrhea were tested for susceptibility to avilamycin, flavomycin, monensin, and salinomycin. Except for flavomycin the substances showed in vitro efficacy comparable to reports of the currently most commonly used drugs for treatment of C. difficile. This indicates that these old compounds may be useful for the treatment of C. difficile infections in man and perhaps for other bacterial causes of diarrhea.
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Affiliation(s)
- Frank M Aarestrup
- EU Reference Laboratory for Antimicrobial Resistance, WHO Collaborating Centre for Antimicrobial Resistance in Foodborne Pathogens, National Food Institute, Technical University of Denmark, Lyngby, Denmark.
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21
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Abstract
Protein synthesis is one of the major targets in the cell for antibiotics. This review endeavors to provide a comprehensive "post-ribosome structure" A-Z of the huge diversity of antibiotics that target the bacterial translation apparatus, with an emphasis on correlating the vast wealth of biochemical data with more recently available ribosome structures, in order to understand function. The binding site, mechanism of action, and modes of resistance for 26 different classes of protein synthesis inhibitors are presented, ranging from ABT-773 to Zyvox. In addition to improving our understanding of the process of translation, insight into the mechanism of action of antibiotics is essential to the development of novel and more effective antimicrobial agents to combat emerging bacterial resistance to many clinically-relevant drugs.
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Affiliation(s)
- Daniel N Wilson
- Gene Center and Department of Chemistry and Biochemistry, University of Munich, LMU, Munich, Germany.
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22
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Llano-Sotelo B, Hickerson RP, Lancaster L, Noller HF, Mankin AS. Fluorescently labeled ribosomes as a tool for analyzing antibiotic binding. RNA (NEW YORK, N.Y.) 2009; 15:1597-1604. [PMID: 19553343 PMCID: PMC2714759 DOI: 10.1261/rna.1681609] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 05/14/2009] [Indexed: 05/28/2023]
Abstract
Measuring the binding of antibiotics and other small-molecular-weight ligands to the 2.5 MDa ribosome often presents formidable challenges. Here, we describe a general method for studying binding of ligands to ribosomes that carry a site-specific fluorescent label covalently attached to one of the ribosomal proteins. As a proof of principle, an environment-sensitive fluorescent group was placed at several specific sites within the ribosomal protein S12. Small ribosomal subunits were reconstituted from native 16S rRNA, individually purified small subunit proteins, and fluorescently labeled S12. The fluorescence characteristics of the reconstituted subunits were affected by several antibiotics, including streptomycin and neomycin, which bind in the vicinity of protein S12. The equilibrium dissociation constants of the drugs obtained using a conventional fluorometer were in good agreement with those observed using previously published methods and with measurements based on the use of radiolabeled streptomycin. The newly developed method is rapid and sensitive, and can be used for determining thermodynamic and kinetic binding characteristics of antibiotics and other small ribosomal ligands. The method can readily be adapted for use in high-throughput screening assays.
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Affiliation(s)
- Beatriz Llano-Sotelo
- Center for Pharmaceutical Biotechnology, University of Illinois, Chicago, Illinois 60607, USA
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23
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Stereoselective synthesis of 1,1′-linked α-l-lyxopyranosyl β-d-glucopyranoside, the proposed biosynthetic precursor of the FG ring system of avilamycins. Carbohydr Res 2008; 343:1612-23. [DOI: 10.1016/j.carres.2008.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 04/29/2008] [Accepted: 05/04/2008] [Indexed: 11/22/2022]
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24
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Brandi L, Fabbretti A, Pon CL, Dahlberg AE, Gualerzi CO. Initiation of protein synthesis: a target for antimicrobials. Expert Opin Ther Targets 2008; 12:519-34. [PMID: 18410237 DOI: 10.1517/14728222.12.5.519] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Translation initiation is a basic and universal biological process that employs significantly different components and displays substantially different mechanisms in bacterial, archaeal and eukaryotic cells. A large amount of detailed mechanistic and structural information on the bacterial translation initiation apparatus has been uncovered in recent years. OBJECTIVE to understand which translation initiation steps could represent a novel or underexploited target for the discovery of new and specific antibacterial drugs. METHODS Brief descriptions of the properties and mechanism of action of the major antibiotics that have a documented direct inhibitory effect on bacterial translation initiation are presented. RESULTS/CONCLUSIONS Considerations and predictions concerning a future scenario for research and identification of bacterial translation initiation inhibitors are presented.
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25
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Interaction of the cyanobacterial toxin cylindrospermopsin with the eukaryotic protein synthesis system. Toxicon 2008; 51:191-8. [DOI: 10.1016/j.toxicon.2007.09.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 08/31/2007] [Accepted: 09/03/2007] [Indexed: 11/22/2022]
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26
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Weidlich M, Klammt C, Bernhard F, Karas M, Stein T. Differential activity profiles of translation inhibitors in whole-cell and cell-free approaches. Lett Appl Microbiol 2007; 46:155-9. [DOI: 10.1111/j.1472-765x.2007.02281.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Boll R, Hofmann C, Heitmann B, Hauser G, Glaser S, Koslowski T, Friedrich T, Bechthold A. The Active Conformation of Avilamycin A Is Conferred by AviX12, a Radical AdoMet Enzyme. J Biol Chem 2006; 281:14756-63. [PMID: 16537546 DOI: 10.1074/jbc.m601508200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The antibiotic avilamycin A is produced by Streptomyces viridochromogenes Tü57. Avilamycin belongs to the family of orthosomycins with a linear heptasaccharide chain linked to a terminal dichloroisoeverninic acid as aglycone. The gene cluster for avilamycin biosynthesis contains 54 open reading frames. Inactivation of one of these genes, namely aviX12, led to the formation of a novel avilamycin derivative named gavibamycin N1. The structure of the new metabolite was confirmed by mass spectrometry (MS) and NMR analysis. It harbors glucose as a component of the heptasaccharide chain instead of a mannose moiety in avilamycin A. Antibacterial activity tests against a spectrum of Gram-positive organisms showed that the new derivative possesses drastically decreased biological activity in comparison to avilamycin A. Thus, AviX12 seems to be implicated in converting avilamycin to its bioactive conformation by catalyzing an unusual epimerization reaction. Sequence comparisons grouped AviX12 in the radical S-adenosylmethionine protein family. AviX12 engineered with a His tag was overexpressed in Escherichia coli and purified by affinity chromatography. The iron sulfur cluster [Fe-S] present in radical AdoMet enzymes was detected in purified AviX12 by means of electron paramagnetic resonance spectroscopy.
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Affiliation(s)
- Raija Boll
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie und Biotechnologie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, D-79104 Freiburg, Germany
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28
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Abstract
Many clinically useful antibiotics exert their antimicrobial effects by blocking protein synthesis on the bacterial ribosome. The structure of the ribosome has recently been determined by X-ray crystallography, revealing the molecular details of the antibiotic-binding sites. The crystal data explain many earlier biochemical and genetic observations, including how drugs exercise their inhibitory effects, how some drugs in combination enhance or impede each other's binding, and how alterations to ribosomal components confer resistance. The crystal structures also provide insight as to how existing drugs might be derivatized (or novel drugs created) to improve binding and circumvent resistance.
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Affiliation(s)
- Jacob Poehlsgaard
- Department of Biochemistry & Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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29
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Hofmann C, Boll R, Heitmann B, Hauser G, Dürr C, Frerich A, Weitnauer G, Glaser SJ, Bechthold A. Genes Encoding Enzymes Responsible for Biosynthesis of L-Lyxose and Attachment of Eurekanate during Avilamycin Biosynthesis. ACTA ACUST UNITED AC 2005; 12:1137-43. [PMID: 16242656 DOI: 10.1016/j.chembiol.2005.08.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 08/01/2005] [Accepted: 08/08/2005] [Indexed: 10/25/2022]
Abstract
The oligosaccharide antibiotic avilamycin A is composed of a polyketide-derived dichloroisoeverninic acid moiety attached to a heptasaccharide chain consisting of six hexoses and one unusual pentose moiety. We describe the generation of mutant strains of the avilamycin producer defective in different sugar biosynthetic genes. Inactivation of two genes (aviD and aviE2) resulted in the breakdown of the avilamycin biosynthesis. In contrast, avilamycin production was not influenced in an aviP mutant. Inactivation of aviGT4 resulted in a mutant that accumulated a novel avilamycin derivative lacking the terminal eurekanate residue. Finally, AviE2 was expressed in Escherichia coli and the gene product was characterized biochemically. AviE2 was shown to convert UDP-D-glucuronic acid to UDP-D-xylose, indicating that the pentose residue of avilamycin A is derived from D-glucose and not from D-ribose. Here we report a UDP-D-glucuronic acid decarboxylase in actinomycetes.
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Affiliation(s)
- Carsten Hofmann
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie und Biotechnologie, Albert-Ludwigs-Universität Freiburg, Germany
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30
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Hermann T. Drugs targeting the ribosome. Curr Opin Struct Biol 2005; 15:355-66. [PMID: 15919197 DOI: 10.1016/j.sbi.2005.05.001] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 01/31/2005] [Accepted: 05/04/2005] [Indexed: 11/30/2022]
Abstract
Several classes of clinically important antibiotics target the bacterial ribosome, where they interfere with microbial protein synthesis. Structural studies of the interaction of antibiotics with the ribosome have revealed that these small molecules recognize predominantly the rRNA components. Over the past two years, three-dimensional structures of ribosome-antibiotic complexes have been determined, providing a detailed picture of the binding sites and mechanism of action of antibacterials, including 'blockbuster' drugs such as the macrolides. Structure-based approaches have come to fruition that comprise the design and crystal structure analysis of novel semi-synthetic antibiotics that target the ribosome decoding site.
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Affiliation(s)
- Thomas Hermann
- Department of Structural Chemistry, Anadys Pharmaceuticals Inc, 3115 Merryfield Row, San Diego, CA 92121, USA.
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31
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Treede I, Hauser G, Mühlenweg A, Hofmann C, Schmidt M, Weitnauer G, Glaser S, Bechthold A. Genes involved in formation and attachment of a two-carbon chain as a component of eurekanate, a branched-chain sugar moiety of avilamycin A. Appl Environ Microbiol 2005; 71:400-6. [PMID: 15640214 PMCID: PMC544256 DOI: 10.1128/aem.71.1.400-406.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eurekanate belongs to the important class of branched-chain carbohydrates present in a wide variety of natural sources. It is a component of avilamycin A, a potent inhibitor of bacterial protein synthesis targeting the 50S ribosomal subunit. The present work provides experimental proof for the function of two genes of the avilamycin biosynthetic gene cluster, aviB1 and aviO2, that are both involved in avilamycin structure modification. The functions of both genes were identified by gene inactivation experiments and nuclear magnetic resonance analyses of extracts produced by the mutants. We suggest that both AviO2 and AviB1 are involved in the biosynthesis of eurekanate within avilamycin biosynthesis. Moreover, two other genes (aviO1 and aviO3) have been inactivated, resulting in a breakdown of avilamycin production in the mutants ITO1 and ITO3, which clearly shows the essential role of both enzymes in avilamycin biosynthesis. The exact functions of both aviO1 and aviO3 remained unknown.
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Affiliation(s)
- Irina Treede
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie und Biotechnologie, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
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32
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Weitnauer G, Hauser G, Hofmann C, Linder U, Boll R, Pelz K, Glaser SJ, Bechthold A. Novel avilamycin derivatives with improved polarity generated by targeted gene disruption. ACTA ACUST UNITED AC 2005; 11:1403-11. [PMID: 15489167 DOI: 10.1016/j.chembiol.2004.08.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Revised: 07/22/2004] [Accepted: 08/04/2004] [Indexed: 10/26/2022]
Abstract
The oligosaccharide antibiotics avilamycin A and C are produced by Streptomyces viridochromogenes Tu57. Both consist of a heptasaccharide chain, which is attached to a polyketide-derived dichloroisoeverninic acid moiety. They show excellent antibiotic activity against Gram-positive bacteria. Both molecules are modified by O-methylation at different positions, which contributes to poor water solubility and difficulties in galenical drug development. In order to generate novel avilamycin derivatives with improved polarity and improved pharmacokinetic properties, we generated a series of mutants with one, two, or three mutated methyltransferase genes. Based on the structure of the novel avilamycin derivatives, the exact function of three methyltransferases, AviG2, AviG5, and AviG6, involved in avilamycin biosynthesis could be assigned.
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Affiliation(s)
- Gabriele Weitnauer
- Pharmazeutische Biologie und Biotechnologie, Institut für Pharmazeutische Wissenschaften, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
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33
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Xiong L, Korkhin Y, Mankin AS. Binding site of the bridged macrolides in the Escherichia coli ribosome. Antimicrob Agents Chemother 2005; 49:281-8. [PMID: 15616307 PMCID: PMC538896 DOI: 10.1128/aac.49.1.281-288.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ketolides represent the latest group of macrolide antibiotics. Tight binding of ketolides to the ribosome appears to correlate with the presence of an extended alkyl-aryl side chain. Recently developed 6,11-bridged bicyclic ketolides extend the spectrum of platforms used to generate new potent macrolides with extended alkyl-aryl side chains. The purpose of the present study was to characterize the site of binding and the action of bridged macrolides in the ribosomes of Escherichia coli. All the bridged macrolides investigated efficiently protected A2058 and A2059 in domain V of 23S rRNA from modification by dimethyl sulfate and U2609 from modification by carbodiimide. In addition, bridged macrolides that carry extended alkyl-aryl side chains protruding from the 6,11 bridge protected A752 in helix 35 of domain II of 23S rRNA from modification by dimethyl sulfate. Bridged macrolides efficiently displaced erythromycin from the ribosome in a competition binding assay. The A2058G mutation in 23S rRNA conferred resistance to the bridged macrolides. The U2609C mutation, which renders E. coli resistant to the previously studied ketolides telithromycin and cethromycin, barely affected cell susceptibility to the bridged macrolides used in this study. The results of the biochemical and genetic studies indicate that in the E. coli ribosome, bridged macrolides bind in the nascent peptide exit tunnel at the site previously described for other macrolide antibiotics. The presence of the side chain promotes the formation of specific interactions with the helix 35 of 23S rRNA.
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Affiliation(s)
- Liqun Xiong
- Center for Pharmaceutical Biotechnology, University of Illinois, 900 S. Ashland Ave., Chicago, IL 60607, USA
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34
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Nishimura M, Yoshida T, Shirouzu M, Terada T, Kuramitsu S, Yokoyama S, Ohkubo T, Kobayashi Y. Solution Structure of Ribosomal Protein L16 from Thermus thermophilus HB8. J Mol Biol 2004; 344:1369-83. [PMID: 15561149 DOI: 10.1016/j.jmb.2004.10.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Revised: 10/06/2004] [Accepted: 10/11/2004] [Indexed: 12/01/2022]
Abstract
Ribosomal protein L16 is an essential component of the bacterial ribosome. It organizes the architecture of aminoacyl tRNA binding site in the ribosome 50S subunit. The three-dimensional structure of L16 from Thermus thermophilus HB8 was determined by NMR. In solution, L16 forms an alpha+beta sandwich structure combined with two additional beta sheets located at the loop regions connecting the two layers. The terminal regions and a central loop region did not show any specific secondary structure. The structured part of L16 could be superimposed well on the C(alpha) model of L16 determined in the crystal structure of the ribosome 50S subunit. By overlaying the L16 solution structure onto the coordinates of the ribosome crystal structure, we constructed the combined model that represents the ribosome-bound state of L16 in the detailed structure. The model showed that L16 possesses residues in contact with helices 38, 39, 42, 43 and 89 of 23S rRNA and helix 4 of 5S rRNA. This suggests its broad effect on the ribosome architecture. Comparison of L16 with the L10e protein, which is the archaeal counterpart, showed that they share a common fold, but differ in some regions of functional importance, especially in the N-terminal region. All known mutation sites in L16 that confer resistance to avilamycin and evernimicin were positioned so that their side-chains were exposed to solvent in the internal cavity of the ribosome. This suggests the direct participation of L16 as a part of the binding site for antibiotics.
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Affiliation(s)
- Mitsuhiro Nishimura
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
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35
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Sunderland J, Lovering AM, Tobin CM, MacGowan AP, Roe JM, Delsol AA. Determination of avilamycin A and B in pig faeces by solid phase extraction and reverse-phase HPLC assay. Int J Antimicrob Agents 2004; 24:511-4. [PMID: 15519487 DOI: 10.1016/j.ijantimicag.2004.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Accepted: 06/02/2004] [Indexed: 11/23/2022]
Abstract
A HPLC method is described for the simultaneous determination of avilamycin A and B in pig faeces, following extraction using acetonitrile and normal-phase solid phase extraction. The HPLC stationary phase was Kromosil 5 micro C-18 with a mobile phase of 48% acetonitrile and 52% 0.01N ammonium acetate buffer, pumped at a flow rate of 1 ml/min. Detection was by UV absorbance at 295 nm and an injection volume of 50 microl was used. Recovery from faeces was >98% and intra-assay precision (CV) was <9.0% for both compounds. The lowest limit of quantification was 0.9 mg/kg (avilamycin A) and 0.2 mg/kg (avilamycin B) with an accuracy of <15% error. No interference was seen from endogenous materials in pig faeces and commonly used veterinary antibiotics.
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Affiliation(s)
- Julie Sunderland
- Bristol Centre for Antimicrobial Research and Evaluation, North Bristol NHS Trust, Southmead Hospital, Bristol, BS105NB, UK.
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36
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Brown JM, Shaw KJ. A novel family of Escherichia coli toxin-antitoxin gene pairs. J Bacteriol 2003; 185:6600-8. [PMID: 14594833 PMCID: PMC262102 DOI: 10.1128/jb.185.22.6600-6608.2003] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2003] [Accepted: 08/25/2003] [Indexed: 11/20/2022] Open
Abstract
Bacterial toxin-antitoxin protein pairs (TA pairs) encode a toxin protein, which poisons cells by binding and inhibiting an essential enzyme, and an antitoxin protein, which binds the toxin and restores viability. We took an approach that did not rely on sequence homology to search for unidentified TA pairs in the genome of Escherichia coli K-12. Of 32 candidate genes tested, ectopic expression of 6 caused growth inhibition. In this report, we focus on the initial characterization of yeeV, ykfI, and ypjF, a novel family of toxin proteins. Coexpression of the gene upstream of each toxin restored the growth rate to that of the uninduced strain. Unexpectedly, we could not detect in vivo protein-protein interactions between the new toxin and antitoxin pairs. Instead, the antitoxins appeared to function by causing a large reduction in the level of cellular toxin protein.
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Affiliation(s)
- Jason M Brown
- Johnson & Johnson Pharmaceutical Research and Development, LLC, La Jolla, California 92121, USA
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37
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Treede I, Jakobsen L, Kirpekar F, Vester B, Weitnauer G, Bechthold A, Douthwaite S. The avilamycin resistance determinants AviRa and AviRb methylate 23S rRNA at the guanosine 2535 base and the uridine 2479 ribose. Mol Microbiol 2003; 49:309-18. [PMID: 12828631 DOI: 10.1046/j.1365-2958.2003.03558.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Avilamycin is an orthosomycin antibiotic that has shown considerable potential for clinical use, although it is presently used as a growth promoter in animal feed. Avilamycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. The ribosomes of the producer strain, Streptomyces viridochromogenes Tü57, are protected from the drug by the action of three resistance factors located in the avilamycin biosynthetic gene cluster. Two of the resistance factors, aviRa and aviRb, encode rRNA methyltransferases that specifically target 23S rRNA. Recombinant AviRa and AviRb proteins retain their activity after purification, and both specifically methylate in vitro transcripts of 23S rRNA domain V. Reverse transcriptase primer extension indicated that AviRa is an N-methyltransferase that targets G2535 within helix 91 of the rRNA, whereas AviRb modified the 2'-O-ribose position of nucleotide U2479 within helix 89. MALDI mass spectrometry confirmed the exact positions of each of these modifications, and additionally established that a single methyl group is added at each nucleotide. Neither of these two nucleotides have previously been described as a target for enzymatic methylation. Molecular models of the 50S subunit crystal structure show that the N-1 of the G2535 base and the 2'-hydroxyl of U2479 are separated by approximately 10 A, a distance that can be spanned by avilamycin. In addition to defining new resistance mechanisms, these data refine our understanding of the probable ribosome contacts made by orthosomycins and of how these antibiotics inhibit protein synthesis.
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Affiliation(s)
- Irina Treede
- Department of Pharmaceutical Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany
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38
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Abstract
The availability of genome sequences is revolutionizing the field of microbiology. Genetic methods are being modified to facilitate rapid analysis at a genome-wide level and are blossoming for human pathogens that were previously considered intractable. This revolution coincided with a growing concern about the emergence of microbial drug resistance, compelling the pharmaceutical industry to search for new antimicrobial agents. The availability of the new technologies, combined with many genetic strategies, has changed the way that researchers approach antibacterial drug discovery.
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Affiliation(s)
- Lynn Miesel
- Department of Antimicrobial Therapy, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, New Jersey 07033-0530, USA.
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39
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Mosbacher TG, Bechthold A, Schulz GE. Crystal structure of the avilamycin resistance-conferring methyltransferase AviRa from Streptomyces viridochromogenes. J Mol Biol 2003; 329:147-57. [PMID: 12742024 DOI: 10.1016/s0022-2836(03)00407-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The emergence of antibiotic-resistant bacterial strains is a widespread problem in contemporary medical practice and drug design. It is therefore important to elucidate the underlying mechanism in each case. The methyltransferase AviRa from Streptomyces viridochromogenes mediates resistance to the antibiotic avilamycin, which is closely related to evernimicin, an oligosaccharide antibiotic that has been used in medical studies. The structure of AviRa was determined by X-ray diffraction at 1.5A resolution. Phases were obtained from one selenomethionine residue introduced by site-directed mutagenesis. The chain-fold is similar to that of most methyltransferases, although AviRa contains two additional helices as a specific feature. A putative-binding site for the cofactor S-adenosyl-L-methionine was derived from homologous structures. It agrees with the conserved pattern of interacting amino acid residues. AviRa methylates a specific guanine base within the peptidyltransferase loop of the 23S ribosomal RNA. Guided by the target, the enzyme was docked to the cognate ribosomal surface, where it fit well into a deep cleft without contacting any ribosomal protein. The two additional alpha-helices of AviRa filled a depression in the surface. Since the transferred methyl group of the cofactor is in a pocket beneath the enzyme surface, the targeted guanine base has to flip out for methylation.
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Affiliation(s)
- Tanja G Mosbacher
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstr. 21, Freiburg im Breisgau, 79104, Germany
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40
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Butaye P, Devriese LA, Haesebrouck F. Antimicrobial growth promoters used in animal feed: effects of less well known antibiotics on gram-positive bacteria. Clin Microbiol Rev 2003; 16:175-88. [PMID: 12692092 PMCID: PMC153145 DOI: 10.1128/cmr.16.2.175-188.2003] [Citation(s) in RCA: 406] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented.
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Affiliation(s)
- Patrick Butaye
- Laboratory of Veterinary Bacteriology and Mycology, Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, University of Ghent, 9820 Merelbeke, Belgium.
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41
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Zarazaga M, Tenorio C, Del Campo R, Ruiz-Larrea F, Torres C. Mutations in ribosomal protein L16 and in 23S rRNA in Enterococcus strains for which evernimicin MICs differ. Antimicrob Agents Chemother 2002; 46:3657-9. [PMID: 12384386 PMCID: PMC128729 DOI: 10.1128/aac.46.11.3657-3659.2002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations in ribosomal protein L16 and in 23S rRNA were investigated in 22 Enterococcus strains of different species and for which the MICs of evernimicin differ (MICs, 0.023 to 16 micro g/ml). Amino acid changes (Arg56His, Ile52Thr, or Arg51His) in protein L16 were found in seven strains, and a nucleotide G2535A mutation in 23S rRNA was found in 1 strain among 13 for which the MICs are > or =1 micro g/ml.
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Affiliation(s)
- Myriam Zarazaga
- Area de Bioquímica y Biología Molecular, Universidad de La Rioja, Logroño, Spain
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42
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Aarestrup FM, McNicholas PM. Incidence of high-level evernimicin resistance in Enterococcus faecium among food animals and humans. Antimicrob Agents Chemother 2002; 46:3088-90. [PMID: 12183279 PMCID: PMC127414 DOI: 10.1128/aac.46.9.3088-3090.2002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Six high-level evernimicin-resistant Enterococcus faecium isolates were identified among 304 avilamycin-resistant E. faecium isolates from animals and 404 stool samples from humans with diarrhea. All four animal isolates, and one of the human isolates, were able to transfer resistance to a susceptible E. faecium strain. The resulting transconjugants all tested positive for the presence of emtA, a gene encoding a methyltransferase previously linked with high-level evernimicin resistance. The four transconjugants derived from animal isolates all carried the same plasmid, while a differently sized plasmid was found in the isolate from humans. This study demonstrated a low incidence of high-level evernimicin resistance mediated by the emtA gene in different E. faecium isolates of animal and human origin.
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43
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Zhong R, Hernandez A, Alton KB, Kishnani NS, Patrick JE. High-performance liquid chromatographic method for the quantification of unbound evernimicin in human plasma ultrafiltrate. J Chromatogr B Analyt Technol Biomed Life Sci 2002; 772:191-5. [PMID: 12016032 DOI: 10.1016/s1570-0232(02)00084-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A rapid HPLC method was developed for quantification of unbound evernimicin in human plasma. Protein-free samples prepared by ultrafiltration were injected directly onto a polymeric reversed-phase column and the eluent monitored at 302 nm. Evernimicin that eluted within 3.5 min was well resolved from endogenous components. Linearity was established between peak height and evernimicin concentration from 25 to 2500 ng/ml. Assay precision (C.V.) was within 5% while bias was no greater than 3%. This method has been used for the ex vivo assessment of evernimicin protein binding in human plasma from safety and tolerance as well as liver dysfunction and renal insufficiency studies.
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Affiliation(s)
- Ruyun Zhong
- Department of Drug Metabolism and Pharmacokinetics, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA.
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44
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Mann PA, Xiong L, Mankin AS, Chau AS, Mendrick CA, Najarian DJ, Cramer CA, Loebenberg D, Coates E, Murgolo NJ, Aarestrup FM, Goering RV, Black TA, Hare RS, McNicholas PM. EmtA, a rRNA methyltransferase conferring high-level evernimicin resistance. Mol Microbiol 2001; 41:1349-56. [PMID: 11580839 DOI: 10.1046/j.1365-2958.2001.02602.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Enterococcus faecium strain 9631355 was isolated from animal sources on the basis of its resistance to the growth promotant avilamycin. The strain also exhibited high-level resistance to evernimicin, a drug undergoing evaluation as a therapeutic agent in humans. Ribosomes from strain 9631355 exhibited a dramatic reduction in evernimicin binding, shown by both cell-free translation assays and direct-binding assays. The resistance determinant was cloned from strain 9631355; sequence alignments suggested it was a methyltransferase and therefore it was designated emtA for evernimicin methyltransferase. Evernimicin resistance was transmissible and emtA was localized to a plasmid-borne insertion element. Purified EmtA methylated 50S subunits from an evernimicin-sensitive strain 30-fold more efficiently than those from a resistant strain. Reverse transcription identified a pause site that was unique to the 23S rRNA extracted from resistant ribosomes. The pause corresponded to methylation of residue G2470 (Escherichia coli numbering). RNA footprinting revealed that G2470 is located within the evernimicin-binding site on the ribosome, thus providing an explanation for the reduced binding of the drug to methylated ribosomes.
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MESH Headings
- Aminoglycosides
- Animals
- Anti-Bacterial Agents/metabolism
- Anti-Bacterial Agents/pharmacology
- Base Sequence
- Binding Sites
- Cloning, Molecular
- DNA Transposable Elements/genetics
- DNA, Bacterial/genetics
- Drug Resistance, Bacterial/genetics
- Drug Resistance, Bacterial/physiology
- Enterococcus faecium/drug effects
- Enterococcus faecium/enzymology
- Enterococcus faecium/genetics
- Genes, Bacterial
- Humans
- Methyltransferases/genetics
- Methyltransferases/metabolism
- Molecular Sequence Data
- Nucleic Acid Conformation
- Plasmids/genetics
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Ribosomal/chemistry
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- Ribosomes/metabolism
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Affiliation(s)
- P A Mann
- Schering Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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45
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Belova L, Tenson T, Xiong L, McNicholas PM, Mankin AS. A novel site of antibiotic action in the ribosome: interaction of evernimicin with the large ribosomal subunit. Proc Natl Acad Sci U S A 2001; 98:3726-31. [PMID: 11259679 PMCID: PMC31120 DOI: 10.1073/pnas.071527498] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Evernimicin (Evn), an oligosaccharide antibiotic, interacts with the large ribosomal subunit and inhibits bacterial protein synthesis. RNA probing demonstrated that the drug protects a specific set of nucleotides in the loops of hairpins 89 and 91 of 23S rRNA in bacterial and archaeal ribosomes. Spontaneous Evn-resistant mutants of Halobacterium halobium contained mutations in hairpins 89 and 91 of 23S rRNA. In the ribosome tertiary structure, rRNA residues involved in interaction with the drug form a tight cluster that delineates the drug-binding site. Resistance mutations in the bacterial ribosomal protein L16, which is shown to be homologous to archaeal protein L10e, cluster to the same region as the rRNA mutations. The Evn-binding site overlaps with the binding site of initiation factor 2. Evn inhibits activity of initiation factor 2 in vitro, suggesting that the drug interferes with formation of the 70S initiation complex. The site of Evn binding and its mode of action are distinct from other ribosome-targeted antibiotics. This antibiotic target site can potentially be used for the development of new antibacterial drugs.
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MESH Headings
- Aminoglycosides
- Anti-Bacterial Agents/pharmacology
- Binding Sites
- Drug Resistance, Microbial/genetics
- Halobacterium salinarum/chemistry
- Halobacterium salinarum/genetics
- Halobacterium salinarum/isolation & purification
- Models, Molecular
- Mutagenesis, Site-Directed
- Nucleic Acid Conformation
- RNA, Archaeal/chemistry
- RNA, Archaeal/drug effects
- RNA, Bacterial/chemistry
- RNA, Bacterial/drug effects
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/drug effects
- RNA, Ribosomal, 23S/genetics
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Affiliation(s)
- L Belova
- Center for Pharmaceutical Biotechnology, M/C 870, University of Illinois, 900 South Ashland Avenue, Chicago, IL 60607, USA
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46
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Weitnauer G, Gaisser S, Trefzer A, Stockert S, Westrich L, Quiros LM, Mendez C, Salas JA, Bechthold A. An ATP-binding cassette transporter and two rRNA methyltransferases are involved in resistance to avilamycin in the producer organism Streptomyces viridochromogenes Tü57. Antimicrob Agents Chemother 2001; 45:690-5. [PMID: 11181344 PMCID: PMC90357 DOI: 10.1128/aac.45.3.690-695.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three different resistance factors from the avilamycin biosynthetic gene cluster of Streptomyces viridochromogenes Tü57, which confer avilamycin resistance when expressed in Streptomyces lividans TK66, were isolated. Analysis of the deduced amino acid sequences showed that AviABC1 is similar to a large family of ATP-binding transporter proteins and that AviABC2 resembles hydrophobic transmembrane proteins known to act jointly with the ATP-binding proteins. The deduced amino acid sequence of aviRb showed similarity to those of other rRNA methyltransferases, and AviRa did not resemble any protein in the databases. Independent expression in S. lividans TK66 of aviABC1 plus aviABC2, aviRa, or aviRb conferred different levels of resistance to avilamycin: 5, 10, or 250 microg/ml, respectively. When either aviRa plus aviRb or aviRa plus aviRb plus aviABC1 plus aviABC2 was coexpressed in S. lividans TK66, avilamycin resistance levels reached more than 250 microg/ml. Avilamycin A inhibited poly(U)-directed polyphenylalanine synthesis in an in vitro system using ribosomes of S. lividans TK66(pUWL201) (GWO), S. lividans TK66(pUWL201-Ra) (GWRa), or S. lividans TK66(pUWL201-Rb) (GWRb), whereas ribosomes of S. lividans TK66 containing pUWL201-Ra+Rb (GWRaRb) were highly resistant. aviRa and aviRb were expressed in Escherichia coli, and both enzymes were purified as fusion proteins to near homogeneity. Both enzymes showed rRNA methyltransferase activity using a mixture of 16S and 23S rRNAs from E. coli as the substrate. Coincubation experiments revealed that the enzymes methylate different positions of rRNA.
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Affiliation(s)
- G Weitnauer
- Pharmazeutische Biologie, Pharmazeutisches Institut, Christian Albrechts Universität zu Kiel, 24118 Kiel, Germany
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47
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McNicholas PM, Mann PA, Najarian DJ, Miesel L, Hare RS, Black TA. Effects of mutations in ribosomal protein L16 on susceptibility and accumulation of evernimicin. Antimicrob Agents Chemother 2001; 45:79-83. [PMID: 11120948 PMCID: PMC90243 DOI: 10.1128/aac.45.1.79-83.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemical mutagenesis of Staphylococcus aureus RN450 generated two strains that displayed a stable reduction (30- to 60-fold) in susceptibility to evernimicin. Cell-free translation reactions demonstrated that the resistance determinant was located in the ribosomal fraction. Compared to ribosomes isolated from a wild-type strain, ribosomes from the mutant strains displayed an 8- to 10-fold reduction in affinity for [(14)C]evernimicin. In contrast, the mutants displayed no alteration in either binding affinity or in vitro susceptibility to erythromycin. Exponential cultures of the mutant strains accumulated significantly less [(14)C]evernimicin than the wild-type strain, suggesting that accumulation is dependent on the high affinity that evernimicin displays for its binding site. Sequencing rplP (encodes ribosomal protein L16) in the mutant strains revealed a single base change in each strain, which resulted in a substitution of either cysteine or histidine for arginine at residue 51. Introduction of a multicopy plasmid carrying wild-type rplP into the mutant strains restored sensitivity to evernimicin, confirming that the alterations in rplP were responsible for the change in susceptibility. Overexpression of the mutant alleles in S. aureus RN450 had no effect on susceptibility to evernimicin, demonstrating that susceptibility is dominant over resistance.
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Affiliation(s)
- P M McNicholas
- Schering Plough Research Institute, Kenilworth, New Jersey 07033, USA.
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48
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Aarestrup FM, Jensen LB. Presence of variations in ribosomal protein L16 corresponding to susceptibility of enterococci to oligosaccharides (Avilamycin and evernimicin). Antimicrob Agents Chemother 2000; 44:3425-7. [PMID: 11083650 PMCID: PMC90215 DOI: 10.1128/aac.44.12.3425-3427.2000] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fragments (414 bp) of the gene-encoding ribosomal protein L16 from Enterococcus faecium and Enterococcus faecalis that were resistant and susceptible to the oligosaccharide antibiotics avilamycin and evernimicin (SCH 27899) were sequenced and compared. The susceptible E. faecalis and E. faecium isolates had sequences that were similar to those of the type strains. All resistant E. faecalis isolates contained the same base pair variation [CGT (Arg-56) --> CAT (His-56)]. The same variation and two additional variations [ATC (Ile-52) --> ACC (Thr-52) and ATC (Ile-52) --> AGC (Ser-52)] were found in the resistant E. faecium isolates. This study indicated that resistance to the oligosaccharides in enterococci is associated with variations in the ribosomal protein L16.
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Affiliation(s)
- F M Aarestrup
- Danish Veterinary Laboratory, DK-1790 Copenhagen V, Denmark.
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49
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Adrian PV, Mendrick C, Loebenberg D, McNicholas P, Shaw KJ, Klugman KP, Hare RS, Black TA. Evernimicin (SCH27899) inhibits a novel ribosome target site: analysis of 23S ribosomal DNA mutants. Antimicrob Agents Chemother 2000; 44:3101-6. [PMID: 11036030 PMCID: PMC101610 DOI: 10.1128/aac.44.11.3101-3106.2000] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2000] [Accepted: 08/21/2000] [Indexed: 11/20/2022] Open
Abstract
Spontaneous mutants of susceptible clinical and laboratory isolates of Streptococcus pneumoniae exhibiting reduced susceptibility to evernimicin (SCH27899; MIC, 0.5 to 4.0 mg/liter) were selected on plates containing evernimicin. Four isolates that did not harbor mutations in rplP (which encodes ribosomal protein L16) were further analyzed. Whole chromosomal DNA or PCR products of the 23S ribosomal DNA (rDNA) operons from these mutants could be used to transform the susceptible S. pneumoniae strain R6 to resistance at frequencies of 10(-5) and 10(-4), respectively, rates 10- to 100-fold lower than that for a single-allele chromosomal marker. The transformants appeared slowly (48 to 72 h) on selective medium, and primary transformants passaged on nonselective medium produced single colonies that displayed heterogeneous susceptibilities to evernimicin. A single passage on selective medium of colonies derived from a single primary transformant homogenized the resistance phenotype. Sequence analysis of the 23S rDNA and rRNA from the resistant mutants revealed single, unique mutations in each isolate at the equivalent Escherichia coli positions 2469 (A --> C), 2480 (C --> T), 2535 (G --> A), and 2536 (G --> C). The mutations map within two different stems of the peptidyltransferase region of domain V. Because multiple copies of rDNA are present in the chromosome, gene conversion between mutant and wild-type 23S rDNA alleles may be necessary for stable resistance. Additionally, none of the characterized mutants showed cross-resistance to any of a spectrum of protein synthesis inhibitors, suggesting that the target site of evernimicin may be unique.
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MESH Headings
- Alleles
- Aminoglycosides
- Anti-Bacterial Agents/pharmacology
- Bacterial Proteins/genetics
- Base Sequence
- DNA, Bacterial/genetics
- Drug Resistance, Microbial
- Humans
- Microbial Sensitivity Tests
- Molecular Sequence Data
- Mutation
- Nucleic Acid Conformation
- RNA, Bacterial/analysis
- RNA, Bacterial/genetics
- RNA, Ribosomal, 23S/chemistry
- RNA, Ribosomal, 23S/drug effects
- RNA, Ribosomal, 23S/genetics
- Streptococcus pneumoniae/drug effects
- Streptococcus pneumoniae/genetics
- Transformation, Bacterial
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Affiliation(s)
- P V Adrian
- Pneumococcal Diseases Research Unit, South African Institute for Medical Research, University of the Witwatersrand, and the Medical Research Council, Johannesburg, South Africa.
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