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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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2
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Osterman IA, Dontsova OA, Sergiev PV. rRNA Methylation and Antibiotic Resistance. BIOCHEMISTRY (MOSCOW) 2021; 85:1335-1349. [PMID: 33280577 DOI: 10.1134/s000629792011005x] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Methylation of nucleotides in rRNA is one of the basic mechanisms of bacterial resistance to protein synthesis inhibitors. The genes for corresponding methyltransferases have been found in producer strains and clinical isolates of pathogenic bacteria. In some cases, rRNA methylation by housekeeping enzymes is, on the contrary, required for the action of antibiotics. The effects of rRNA modifications associated with antibiotic efficacy may be cooperative or mutually exclusive. Evolutionary relationships between the systems of rRNA modification by housekeeping enzymes and antibiotic resistance-related methyltransferases are of particular interest. In this review, we discuss the above topics in detail.
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Affiliation(s)
- I A Osterman
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 143028, Russia.,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - O A Dontsova
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 143028, Russia.,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.,Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - P V Sergiev
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 143028, Russia. .,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.,Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, 119991, Russia
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3
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Microbial Oligosaccharides with Biomedical Applications. Mar Drugs 2021; 19:md19060350. [PMID: 34205503 PMCID: PMC8234114 DOI: 10.3390/md19060350] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/09/2021] [Accepted: 06/16/2021] [Indexed: 11/17/2022] Open
Abstract
Microbial oligosaccharides have been regarded as one of the most appealing natural products attributable to their potent and selective bioactivities, such as antimicrobial activity, inhibition of α-glucosidases and lipase, interference of cellular recognition and signal transduction, and disruption of cell wall biosynthesis. Accordingly, a handful of bioactive oligosaccharides have been developed for the treatment of bacterial infections and type II diabetes mellitus. Given that naturally occurring oligosaccharides have increasingly gained recognition in recent years, a comprehensive review is needed. The current review highlights the chemical structures, biological activities and divergent biosynthetic origins of three subgroups of oligomers including the acarviosine-containing oligosaccharides, saccharomicins, and orthosomycins.
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4
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Abstract
During the past decades resistance to virtually all antimicrobial agents has been observed in bacteria of animal origin. This chapter describes in detail the mechanisms so far encountered for the various classes of antimicrobial agents. The main mechanisms include enzymatic inactivation by either disintegration or chemical modification of antimicrobial agents, reduced intracellular accumulation by either decreased influx or increased efflux of antimicrobial agents, and modifications at the cellular target sites (i.e., mutational changes, chemical modification, protection, or even replacement of the target sites). Often several mechanisms interact to enhance bacterial resistance to antimicrobial agents. This is a completely revised version of the corresponding chapter in the book Antimicrobial Resistance in Bacteria of Animal Origin published in 2006. New sections have been added for oxazolidinones, polypeptides, mupirocin, ansamycins, fosfomycin, fusidic acid, and streptomycins, and the chapters for the remaining classes of antimicrobial agents have been completely updated to cover the advances in knowledge gained since 2006.
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5
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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: 14] [Impact Index Per Article: 1.8] [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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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: 35] [Impact Index Per Article: 4.4] [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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7
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Cundliffe E, Demain AL. Avoidance of suicide in antibiotic-producing microbes. J Ind Microbiol Biotechnol 2010; 37:643-72. [PMID: 20446033 DOI: 10.1007/s10295-010-0721-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 03/30/2010] [Indexed: 11/29/2022]
Abstract
Many microbes synthesize potentially autotoxic antibiotics, mainly as secondary metabolites, against which they need to protect themselves. This is done in various ways, ranging from target-based strategies (i.e. modification of normal drug receptors or de novo synthesis of the latter in drug-resistant form) to the adoption of metabolic shielding and/or efflux strategies that prevent drug-target interactions. These self-defence mechanisms have been studied most intensively in antibiotic-producing prokaryotes, of which the most prolific are the actinomycetes. Only a few documented examples pertain to lower eukaryotes while higher organisms have hardly been addressed in this context. Thus, many plant alkaloids, variously described as herbivore repellents or nitrogen excretion devices, are truly antibiotics-even if toxic to humans. As just one example, bulbs of Narcissus spp. (including the King Alfred daffodil) accumulate narciclasine that binds to the larger subunit of the eukaryotic ribosome and inhibits peptide bond formation. However, ribosomes in the Amaryllidaceae have not been tested for possible resistance to narciclasine and other alkaloids. Clearly, the prevalence of suicide avoidance is likely to extend well beyond the remit of the present article.
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Affiliation(s)
- Eric Cundliffe
- Department of Biochemistry, University of Leicester, Leicester, LE1 9HN, UK.
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8
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Rebets Y, Boll R, Horbal L, Fedorenko V, Bechthold A. Production of avilamycin A is regulated by AviC1 and AviC2, two transcriptional activators. J Antibiot (Tokyo) 2009; 62:461-4. [PMID: 19609289 DOI: 10.1038/ja.2009.63] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yuriy Rebets
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie und Biotechnologie, Universität Freiburg, Freiburg im Breisgau, Germany
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9
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Abstract
Antibiotic resistance is a fundamental aspect of microbiology, but it is also a phenomenon of vital importance in the treatment of diseases caused by pathogenic microorganisms. A resistance mechanism can involve an inherent trait or the acquisition of a new characteristic through either mutation or horizontal gene transfer. The natural susceptibilities of bacteria to a certain drug vary significantly from one species of bacteria to another and even from one strain to another. Once inside the cell, most antibiotics affect all bacteria similarly. The ribosome is a major site of antibiotic action and is targeted by a large and chemically diverse group of antibiotics. A number of these antibiotics have important applications in human and veterinary medicine in the treatment of bacterial infections. The antibiotic binding sites are clustered at functional centers of the ribosome, such as the decoding center, the peptidyl transferase center, the GTPase center, the peptide exit tunnel, and the subunit interface spanning both subunits on the ribosome. Upon binding, the drugs interfere with the positioning and movement of substrates, products, and ribosomal components that are essential for protein synthesis. Ribosomal antibiotic resistance is due to the alteration of the antibiotic binding sites through either mutation or methylation. Our knowledge of antibiotic resistance mechanisms has increased, in particular due to the elucidation of the detailed structures of antibiotic-ribosome complexes and the components of the efflux systems. A number of mutations and methyltransferases conferring antibiotic resistance have been characterized. These developments are important for understanding and approaching the problems associated with antibiotic resistance, including design of antimicrobials that are impervious to known bacterial resistance mechanisms.
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10
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Zhu CH, Lu FP, He YN, Han ZL, Du LX. Regulation of avilamycin biosynthesis in Streptomyces viridochromogenes: effects of glucose, ammonium ion, and inorganic phosphate. Appl Microbiol Biotechnol 2007; 73:1031-8. [PMID: 16941176 DOI: 10.1007/s00253-006-0572-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 06/19/2006] [Accepted: 07/09/2006] [Indexed: 11/30/2022]
Abstract
Effects of glucose, ammonium ions and phosphate on avilamycin biosynthesis in Streptomyces viridochromogenes AS4.126 were investigated. Twenty grams per liter of glucose, 10 mmol/L ammonium ions, and 10 mmol/L phosphate in the basal medium stimulated avilamycin biosynthesis. When the concentrations of glucose, ammonium ions, and phosphate in the basal medium exceeded 20 g/L, 10 mmol/L, and 10 mmol/L, respectively, avilamycin biosynthesis greatly decreased. When 20 g/L glucose was added at 32 h, avilamycin yield decreased by 70.2%. Avilamycin biosynthesis hardly continued when 2-deoxy-glucose was added into the basal medium at 32 h. There was little influence on avilamycin biosynthesis with the addition of the 3-methyl-glucose (20 g/L) at 32 h. In the presence of excess (NH4)2SO4 (20 mmol/L), the activities of valine dehydrogenase and glucose-6-phosphate dehydrogenase were depressed 47.7 and 58.3%, respectively, of that of the control at 48 h. The activity of succinate dehydrogenase increased 49.5% compared to the control at 48 h. The intracellular adenosine triphosphate level and 6-phosphate glucose content of S. viridochromogenes were 128 and 129%, respectively, of that of the control at 48 h, with the addition of the 40 mmol/L of KH2PO4. As a result, high concentrations of glucose, ammonium ions, and inorganic phosphate all led to the absence of the precursors for avilamycin biosynthesis and affected antibiotic synthesis.
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Affiliation(s)
- Chuan-he Zhu
- Tianjin Key Lab of Industrial Microbiology, College of Biotechnology, Tianjin University of Science and Technology, 30022, Tianjin, People's Republic of China
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11
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Bililign T, Hyun CG, Williams JS, Czisny AM, Thorson JS. The hedamycin locus implicates a novel aromatic PKS priming mechanism. ACTA ACUST UNITED AC 2005; 11:959-69. [PMID: 15271354 DOI: 10.1016/j.chembiol.2004.04.016] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Revised: 04/19/2004] [Accepted: 04/26/2004] [Indexed: 11/18/2022]
Abstract
The biosynthetic gene cluster for the pluramycin-type antitumor antibiotic hedamycin has been cloned from Streptomyces griseoruber. Sequence analysis of the 45.6 kb region revealed a variety of unique features such as a fabH homolog (KSIII), an acyltransferase (AT) gene, a set of type I polyketide synthase (PKS) genes, and two putative C-glycosyltransferase genes. As the first report of the cloning of the biosynthetic gene cluster for the pluramycin antibiotics, this work suggests that the biosynthesis of pluramycins utilize an iterative type I PKS system for the generation of a novel starter unit that subsequently primes the type II PKS system. It also implicates the involvement of a second catalytic ketosynthase (KSIII) to regulate this unusual priming step. Gene disruption is used to confirm the importance of both type I and II PKS genes for the biosynthesis of hedamycin.
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Affiliation(s)
- Tsion Bililign
- Laboratory for Biosynthetic Chemistry, Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705, USA
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12
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Mosbacher TG, Bechthold A, Schulz GE. Structure and function of the antibiotic resistance-mediating methyltransferase AviRb from Streptomyces viridochromogenes. J Mol Biol 2005; 345:535-45. [PMID: 15581897 DOI: 10.1016/j.jmb.2004.10.051] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Revised: 10/15/2004] [Accepted: 10/15/2004] [Indexed: 11/24/2022]
Abstract
The emergence of antibiotic-resistant bacterial strains is a widespread problem in medical practice and drug design, and each case requires the elucidation of the underlying mechanism. AviRb from Streptomyces viridochromogenes methylates the 2'-O atom of U2479 of the 23S ribosomal RNA in Gram-positive bacteria and thus mediates resistance to the oligosaccharide (orthosomycin) antibiotic avilamycin. The structure of AviRb with and without bound cofactor S-adenosyl-L-methionine (AdoMet) was determined, showing that it is a homodimer belonging to the SpoU family within the SPOUT class of methyltransferases. The relationships within this class were analyzed in detail and, in addition, a novel fourth SpoU sequence fingerprint is proposed. Each subunit of AviRb consists of two domains. The N-terminal domain, being related to the ribosomal proteins L30 and L7Ae, is likely to bind RNA. The C-terminal domain is related to all SPOUT methyltransferases, and is responsible for AdoMet-binding, catalysis and dimerization. The cofactor binds at the characteristic knot of the polypeptide in an unusually bent conformation. The transferred methyl group points to a broad cleft formed with the L30-type domain of the other subunit. Measurements of mutant activity revealed four important residues responsible for catalysis and allowed the modeling of a complex between AviRb and the RNA target. The model includes a specificity pocket for uracil but does not contain a base for deprotonating the 2'-O atom of U2479 on methylation.
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Affiliation(s)
- Tanja G Mosbacher
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstr. 21, D-79104 Freiburg im Breisgau, Germany
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13
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Bechthold A, Weitnauer G, Luzhetskyy A, Berner M, Bihlmeier C, Boll R, Dürr C, Frerich A, Hofmann C, Mayer A, Treede I, Vente A, Luzhetskyy M. Glycosyltransferases and other tailoring enzymes as tools for the generation of novel compounds. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2005:147-63. [PMID: 15645720 DOI: 10.1007/3-540-27055-8_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- A Bechthold
- Institut für Pharmazeutische Wissenschaften, Albert-Ludwigs-Universität Freiburg, Germany.
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14
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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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15
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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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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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17
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Kofoed CB, Vester B. Interaction of avilamycin with ribosomes and resistance caused by mutations in 23S rRNA. Antimicrob Agents Chemother 2002; 46:3339-42. [PMID: 12384333 PMCID: PMC128742 DOI: 10.1128/aac.46.11.3339-3342.2002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antibiotic growth promoter avilamycin inhibits protein synthesis by binding to bacterial ribosomes. Here the binding site is further characterized on Escherichia coli ribosomes. The drug interacts with domain V of 23S rRNA, giving a chemical footprint at nucleotides A2482 and A2534. Selection of avilamycin-resistant Halobacterium halobium cells revealed mutations in helix 89 of 23S rRNA. Furthermore, mutations in helices 89 and 91, which have previously been shown to confer resistance to evernimicin, give cross-resistance to avilamycin. These data place the binding site of avilamycin on 23S rRNA close to the elbow of A-site tRNA. It is inferred that avilamycin interacts with the ribosomes at the ribosomal A-site interfering with initiation factor IF2 and tRNA binding in a manner similar to evernimicin.
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Affiliation(s)
- Christine B Kofoed
- Institute of Molecular Biology, University of Copenhagen, DK-1307 Copenhagen K, Denmark
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Michel G, Sauvé V, Larocque R, Li Y, Matte A, Cygler M. The structure of the RlmB 23S rRNA methyltransferase reveals a new methyltransferase fold with a unique knot. Structure 2002; 10:1303-15. [PMID: 12377117 DOI: 10.1016/s0969-2126(02)00852-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In Escherichia coli, RlmB catalyzes the methylation of guanosine 2251, a modification conserved in the peptidyltransferase domain of 23S rRNA. The crystal structure of this 2'O-methyltransferase has been determined at 2.5 A resolution. RlmB consists of an N-terminal domain connected by a flexible extended linker to a catalytic C-terminal domain and forms a dimer in solution. The C-terminal domain displays a divergent methyltransferase fold with a unique knotted region, and lacks the classic AdoMet binding site features. The N-terminal domain is similar to ribosomal proteins L7 and L30, suggesting a role in 23S rRNA recognition. The conserved residues in this novel family of 2'O-methyltransferases cluster in the knotted region, suggesting the location of the catalytic and AdoMet binding sites.
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Affiliation(s)
- Gurvan Michel
- Biotechnology Research Institute, National Research Council of Canada and Montreal Joint Centre for Structural Biology, Montreal, Quebec, Canada
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19
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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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20
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Weitnauer G, Mühlenweg A, Trefzer A, Hoffmeister D, Süssmuth RD, Jung G, Welzel K, Vente A, Girreser U, Bechthold A. Biosynthesis of the orthosomycin antibiotic avilamycin A: deductions from the molecular analysis of the avi biosynthetic gene cluster of Streptomyces viridochromogenes Tü57 and production of new antibiotics. CHEMISTRY & BIOLOGY 2001; 8:569-81. [PMID: 11410376 DOI: 10.1016/s1074-5521(01)00040-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Streptomyces viridochromogenes Tü57 is the producer of avilamycin A. The antibiotic consists of a heptasaccharide side chain and a polyketide-derived dichloroisoeverninic acid as aglycone. Molecular cloning and characterization of the genes governing the avilamycin A biosynthesis is of major interest as this information might set the direction for the development of new antimicrobial agents. RESULTS A 60-kb section of the S. viridochromogenes Tü57 chromosome containing genes involved in avilamycin biosynthesis was sequenced. Analysis of the DNA sequence revealed 54 open reading frames. Based on the putative function of the gene products a model for avilamycin biosynthesis is proposed. Inactivation of aviG4 and aviH, encoding a methyltransferase and a halogenase, respectively, prevented the mutant strains from producing the complete dichloroisoeverninic acid moiety resulting in the accumulation of new antibiotics named gavibamycins. CONCLUSIONS The avilamycin A biosynthetic gene cluster represents an interesting system to study the formation and attachment of unusual deoxysugars. Several enzymes putatively responsible for specific steps of this pathway could be assigned. Two genes encoding enzymes involved in post-PKS tailoring reactions were deleted allowing the production of new analogues of avilamycin A.
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Affiliation(s)
- G Weitnauer
- Albert-Ludwigs-Universität Freiburg, Institut für Pharmazeutische Biologie, Germany
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