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Birte Vester - One of the best experts on this subject based on the ideXlab platform.

  • Interaction of Pleuromutilin derivatives with the ribosomal peptidyl transferase
    2015
    Co-Authors: Katherine S Long, Lykke Haastrup Hansen, Lene Jakobsen, Birte Vester
    Abstract:

    Tiamulin is a Pleuromutilin antibiotic that is used in veterinary medicine. The recently published crystal structure of a tiamulin-50S ribosomal subunit complex provides detailed information about how this drug targets the peptidyl transferase center of the ribosome. To promote rational design of Pleuromutilin-based drugs, the binding of the antibiotic Pleuromutilin and three semisynthetic derivatives with different side chain extensions has been investigated using chemical footprinting. The nucleotides A2058, A2059, G2505, and U2506 are affected in all of the footprints, suggesting that the drugs are similarly anchored in the binding pocket by the common tricyclic mutilin core. However, varying effects are observed at U2584 and U2585, indicating that the side chain extensions adopt distinct conformations within the cavity and thereby affect the rRNA confor-mation differently. An Escherichia coli L3 mutant strain is resistant to tiamulin and Pleuromutilin, but not valnemulin, implying that valnemulin is better able to withstand an altered rRNA binding surface around the mutilin core. This is likely due to additional interactions made between the valnemulin side chain extension and the rRNA binding site. The data suggest that Pleuromutilin drugs with enhanced antimicrobial activity may be obtained by maximizing the number of interactions between the side chain moiety and the peptidyl transferase cavity. Tiamulin and valnemulin are used in veterinary medicine t

  • a click chemistry approach to Pleuromutilin derivatives part 3 extended footprinting analysis and excellent mrsa inhibition for a derivative with an adenine phenyl side chain
    Bioorganic & Medicinal Chemistry Letters, 2014
    Co-Authors: Ida Dreier, Poul Nielsen, Lykke Haastrup Hansen, Birte Vester
    Abstract:

    Five promising Pleuromutilin derivatives from our former studies, all containing adenine on various linkers, were supplemented with two new compounds. The binding to Escherichia coli ribosomes was verified by extensive chemical footprinting analysis. The ability to inhibit bacterial growth was investigated on two Staphylococcus aureus strains and compared to the Pleuromutilin drugs tiamulin and valnemulin. Three of the compounds show an effect similar to tiamulin and one compound shows an excellent effect similar to valnemulin.

  • A click chemistry approach to Pleuromutilin derivatives, part 2: conjugates with acyclic nucleosides and their ribosomal binding and antibacterial activity.
    Journal of Medicinal Chemistry, 2012
    Co-Authors: Ida Dreier, Birte Vester, Lykke Haastrup Hansen, Surender Kumar, Helle Søndergaard, Maria Louise Rasmussen, Nanna Holmgaard List, Jacob Kongsted, Poul Nielsen
    Abstract:

    Pleuromutilin is an antibiotic that binds to bacterial ribosomes and thereby inhibit protein synthesis. A new series of semisynthetic Pleuromutilin derivatives were synthesized by a click chemistry strategy. Pleuromutilin was conjugated by different linkers to a nucleobase, nucleoside, or phenyl group, as a side-chain extension at the C22 position of Pleuromutilin. The linkers were designed on the basis of the best linker from our first series of Pleuromutilin derivatives following either conformational restriction or an isosteric methylene to oxygen exchange. The binding of the new compounds to the Escherichia coli ribosome was investigated by molecular modeling and chemical footprinting of nucleotide U2506, and it was found that all the derivatives bind to the specific site and most of them better than Pleuromutilin itself. The effect of the side-chain extension was also explored by chemical footprinting of nucleotide U2585, and the results showed that all the compounds interact with this position to va...

  • single 23s rrna mutations at the ribosomal peptidyl transferase centre confer resistance to valnemulin and other antibiotics in mycobacterium smegmatis by perturbation of the drug binding pocket
    Molecular Microbiology, 2009
    Co-Authors: Katherine S Long, Lykke Haastrup Hansen, Jacob Poehlsgaard, Sven N Hobbie, Erik C Bottger, Birte Vester
    Abstract:

    Summary Tiamulin and valnemulin target the peptidyl transferase centre (PTC) on the bacterial ribosome. They are used in veterinary medicine to treat infections caused by a variety of bacterial pathogens, including the intestinal spirochetes Brachyspira spp. Mutations in ribosomal protein L3 and 23S rRNA have previously been associated with tiamulin resistance in Brachyspira spp. isolates, but as multiple mutations were isolated together, the roles of the individual mutations are unclear. In this work, individual 23S rRNA mutations associated with Pleuromutilin resistance at positions 2055, 2447, 2504 and 2572 (Escherichia coli numbering) are introduced into a Mycobacterium smegmatis strain with a single rRNA operon. The single mutations each confer a significant and similar degree of valnemulin resistance and those at 2447 and 2504 also confer cross-resistance to other antibiotics that bind to the PTC in M. smegmatis. Antibiotic footprinting experiments on mutant ribosomes show that the introduced mutations cause structural perturbations at the PTC and reduced binding of Pleuromutilin antibiotics. This work underscores the fact that mutations at nucleotides distant from the Pleuromutilin binding site can confer the same level of valnemulin resistance as those at nucleotides abutting the bound drug, and suggests that the former function indirectly by altering local structure and flexibility at the drug binding pocket.

  • A click chemistry approach to Pleuromutilin conjugates with nucleosides or acyclic nucleoside derivatives and their binding to the bacterial ribosome.
    Journal of Medicinal Chemistry, 2008
    Co-Authors: Line Lolk, Birte Vester, Lykke Haastrup Hansen, Jacob Pøhlsgaard, Anne Sofie Jepsen, Henrik Nielsen, Signe Inglev Steffansen, Laura Sparving, Annette Bjerre Nielsen, Poul Nielsen
    Abstract:

    Pleuromutilin and its derivatives are antibacterial drugs that inhibit protein synthesis in bacteria by binding to ribosomes. To promote rational design of Pleuromutilin based drugs, 19 Pleuromutilin conjugates with different nucleoside fragments as side chain extensions were synthesized by a click chemistry protocol. Binding was assessed by chemical footprinting of nucleotide U2506 in 23S rRNA, and all conjugates bind to varying degree reflecting their binding affinity to the peptidyl transferase center. The side chain extensions also show various protections at position U2585. Docking studies of the conjugates with the highest affinities support the conclusion that despite the various conjugations, the pleuomutilin skeleton binds in the same binding pocket. The conjugated triazole moiety is well accommodated, and the nucleobases are placed in different pockets in the 50S ribosomal subunit. The derivative showing the highest affinity and a significantly better binding than Pleuromutilin itself contains an adenine-9-ylpropylene triazole conjugate to Pleuromutilin C-22.

Andy M. Bailey - One of the best experts on this subject based on the ideXlab platform.

  • Heterologous expression reveals the biosynthesis of the antibiotic Pleuromutilin and generates bioactive semi-synthetic derivatives.
    Nature Communications, 2017
    Co-Authors: Fabrizio Alberti, Khairunisa Khairudin, Edith Rodriguez Venegas, Jonathan A. Davies, Patrick M. Hayes, Christine L. Willis, Andy M. Bailey, Gary D. Foster
    Abstract:

    The rise in antibiotic resistance is a major threat for human health. Basidiomycete fungi represent an untapped source of underexploited antimicrobials, with Pleuromutilin—a diterpene produced by Clitopilus passeckerianus—being the only antibiotic from these fungi leading to commercial derivatives. Here we report genetic characterisation of the steps involved in Pleuromutilin biosynthesis, through rational heterologous expression in Aspergillus oryzae coupled with isolation and detailed structural elucidation of the pathway intermediates by spectroscopic methods and comparison with synthetic standards. A. oryzae was further established as a platform for bio-conversion of chemically modified analogues of Pleuromutilin intermediates, and was employed to generate a semi-synthetic Pleuromutilin derivative with enhanced antibiotic activity. These studies pave the way for future characterisation of biosynthetic pathways of other basidiomycete natural products in ascomycete heterologous hosts, and open up new possibilities of further chemical modification for the growing class of potent Pleuromutilin antibiotics.

  • Heterologous expression reveals the biosynthesis of the antibiotic Pleuromutilin and generates bioactive semi-synthetic derivatives
    Nature Publishing Group, 2017
    Co-Authors: Fabrizio Alberti, Khairunisa Khairudin, Edith Rodriguez Venegas, Jonathan A. Davies, Patrick M. Hayes, Christine L. Willis, Andy M. Bailey, Gary D. Foster
    Abstract:

    Pleuromutilin derivatives are potent antibacterial drugs obtained from Basidiomycete fungi. Here, the authors report the genetic characterisation of the steps involved in Pleuromutilin biosynthesis through heterologous expression and generate a semi-synthetic Pleuromutilin derivative with enhanced antibiotic activity

  • Identification and manipulation of the Pleuromutilin gene cluster from Clitopilus passeckerianus for increased rapid antibiotic production.
    Scientific Reports, 2016
    Co-Authors: Andy M. Bailey, Fabrizio Alberti, Amanda J Hartley, Catherine Majella Collins, Sreedhar Kilaru, Kate M. J. De Mattos-shipley, Patrick L. Hayes, Alison Griffin, Colin M. Lazarus, Russell J. Cox
    Abstract:

    Semi-synthetic derivatives of the tricyclic diterpene antibiotic Pleuromutilin from the basidiomycete Clitopilus passeckerianus are important in combatting bacterial infections in human and veterinary medicine. These compounds belong to the only new class of antibiotics for human applications, with novel mode of action and lack of cross-resistance, representing a class with great potential. Basidiomycete fungi, being dikaryotic, are not generally amenable to strain improvement. We report identification of the seven-gene Pleuromutilin gene cluster and verify that using various targeted approaches aimed at increasing antibiotic production in C. passeckerianus, no improvement in yield was achieved. The seven-gene Pleuromutilin cluster was reconstructed within Aspergillus oryzae giving production of Pleuromutilin in an ascomycete, with a significant increase (2106%) in production. This is the first gene cluster from a basidiomycete to be successfully expressed in an ascomycete, and paves the way for the exploitation of a metabolically rich but traditionally overlooked group of fungi.

  • investigating Pleuromutilin producing clitopilus species and related basidiomycetes
    Fems Microbiology Letters, 2009
    Co-Authors: Amanda J Hartley, Gary D. Foster, Kate M J De Mattosshipley, Catherine Majella Collins, Sreedhar Kilaru, Andy M. Bailey
    Abstract:

    Pleuromutilin is a broad-spectrum antibiotic that has been used in veterinary medicine for over 20 years, but is now gaining interest as a human therapeutic. The compound is a fungal secondary metabolite, but there is some degree of confusion within the literature concerning which species may produce Pleuromutilin, with several differently named fungi reported to make the compound. Here, we describe a taxonomic survey of publicly available cultures known to produce Pleuromutilin, and other similar species. The Pleuromutilin production of these strains was assessed and a phylogenetic assessment was carried out based on the sequence of the nuclear rRNA internal transcribed spacer region. Eleven strains were confirmed as being Pleuromutilin producers and all of these isolates appear to fall within a discrete clade of the genus Clitopilus. The phylogenetic analysis also highlights the need for a revision of the taxonomic status of these fungi.

Samir Z Zard - One of the best experts on this subject based on the ideXlab platform.

Lykke Haastrup Hansen - One of the best experts on this subject based on the ideXlab platform.

  • Interaction of Pleuromutilin derivatives with the ribosomal peptidyl transferase
    2015
    Co-Authors: Katherine S Long, Lykke Haastrup Hansen, Lene Jakobsen, Birte Vester
    Abstract:

    Tiamulin is a Pleuromutilin antibiotic that is used in veterinary medicine. The recently published crystal structure of a tiamulin-50S ribosomal subunit complex provides detailed information about how this drug targets the peptidyl transferase center of the ribosome. To promote rational design of Pleuromutilin-based drugs, the binding of the antibiotic Pleuromutilin and three semisynthetic derivatives with different side chain extensions has been investigated using chemical footprinting. The nucleotides A2058, A2059, G2505, and U2506 are affected in all of the footprints, suggesting that the drugs are similarly anchored in the binding pocket by the common tricyclic mutilin core. However, varying effects are observed at U2584 and U2585, indicating that the side chain extensions adopt distinct conformations within the cavity and thereby affect the rRNA confor-mation differently. An Escherichia coli L3 mutant strain is resistant to tiamulin and Pleuromutilin, but not valnemulin, implying that valnemulin is better able to withstand an altered rRNA binding surface around the mutilin core. This is likely due to additional interactions made between the valnemulin side chain extension and the rRNA binding site. The data suggest that Pleuromutilin drugs with enhanced antimicrobial activity may be obtained by maximizing the number of interactions between the side chain moiety and the peptidyl transferase cavity. Tiamulin and valnemulin are used in veterinary medicine t

  • a click chemistry approach to Pleuromutilin derivatives part 3 extended footprinting analysis and excellent mrsa inhibition for a derivative with an adenine phenyl side chain
    Bioorganic & Medicinal Chemistry Letters, 2014
    Co-Authors: Ida Dreier, Poul Nielsen, Lykke Haastrup Hansen, Birte Vester
    Abstract:

    Five promising Pleuromutilin derivatives from our former studies, all containing adenine on various linkers, were supplemented with two new compounds. The binding to Escherichia coli ribosomes was verified by extensive chemical footprinting analysis. The ability to inhibit bacterial growth was investigated on two Staphylococcus aureus strains and compared to the Pleuromutilin drugs tiamulin and valnemulin. Three of the compounds show an effect similar to tiamulin and one compound shows an excellent effect similar to valnemulin.

  • A click chemistry approach to Pleuromutilin derivatives, part 2: conjugates with acyclic nucleosides and their ribosomal binding and antibacterial activity.
    Journal of Medicinal Chemistry, 2012
    Co-Authors: Ida Dreier, Birte Vester, Lykke Haastrup Hansen, Surender Kumar, Helle Søndergaard, Maria Louise Rasmussen, Nanna Holmgaard List, Jacob Kongsted, Poul Nielsen
    Abstract:

    Pleuromutilin is an antibiotic that binds to bacterial ribosomes and thereby inhibit protein synthesis. A new series of semisynthetic Pleuromutilin derivatives were synthesized by a click chemistry strategy. Pleuromutilin was conjugated by different linkers to a nucleobase, nucleoside, or phenyl group, as a side-chain extension at the C22 position of Pleuromutilin. The linkers were designed on the basis of the best linker from our first series of Pleuromutilin derivatives following either conformational restriction or an isosteric methylene to oxygen exchange. The binding of the new compounds to the Escherichia coli ribosome was investigated by molecular modeling and chemical footprinting of nucleotide U2506, and it was found that all the derivatives bind to the specific site and most of them better than Pleuromutilin itself. The effect of the side-chain extension was also explored by chemical footprinting of nucleotide U2585, and the results showed that all the compounds interact with this position to va...

  • single 23s rrna mutations at the ribosomal peptidyl transferase centre confer resistance to valnemulin and other antibiotics in mycobacterium smegmatis by perturbation of the drug binding pocket
    Molecular Microbiology, 2009
    Co-Authors: Katherine S Long, Lykke Haastrup Hansen, Jacob Poehlsgaard, Sven N Hobbie, Erik C Bottger, Birte Vester
    Abstract:

    Summary Tiamulin and valnemulin target the peptidyl transferase centre (PTC) on the bacterial ribosome. They are used in veterinary medicine to treat infections caused by a variety of bacterial pathogens, including the intestinal spirochetes Brachyspira spp. Mutations in ribosomal protein L3 and 23S rRNA have previously been associated with tiamulin resistance in Brachyspira spp. isolates, but as multiple mutations were isolated together, the roles of the individual mutations are unclear. In this work, individual 23S rRNA mutations associated with Pleuromutilin resistance at positions 2055, 2447, 2504 and 2572 (Escherichia coli numbering) are introduced into a Mycobacterium smegmatis strain with a single rRNA operon. The single mutations each confer a significant and similar degree of valnemulin resistance and those at 2447 and 2504 also confer cross-resistance to other antibiotics that bind to the PTC in M. smegmatis. Antibiotic footprinting experiments on mutant ribosomes show that the introduced mutations cause structural perturbations at the PTC and reduced binding of Pleuromutilin antibiotics. This work underscores the fact that mutations at nucleotides distant from the Pleuromutilin binding site can confer the same level of valnemulin resistance as those at nucleotides abutting the bound drug, and suggests that the former function indirectly by altering local structure and flexibility at the drug binding pocket.

  • A click chemistry approach to Pleuromutilin conjugates with nucleosides or acyclic nucleoside derivatives and their binding to the bacterial ribosome.
    Journal of Medicinal Chemistry, 2008
    Co-Authors: Line Lolk, Birte Vester, Lykke Haastrup Hansen, Jacob Pøhlsgaard, Anne Sofie Jepsen, Henrik Nielsen, Signe Inglev Steffansen, Laura Sparving, Annette Bjerre Nielsen, Poul Nielsen
    Abstract:

    Pleuromutilin and its derivatives are antibacterial drugs that inhibit protein synthesis in bacteria by binding to ribosomes. To promote rational design of Pleuromutilin based drugs, 19 Pleuromutilin conjugates with different nucleoside fragments as side chain extensions were synthesized by a click chemistry protocol. Binding was assessed by chemical footprinting of nucleotide U2506 in 23S rRNA, and all conjugates bind to varying degree reflecting their binding affinity to the peptidyl transferase center. The side chain extensions also show various protections at position U2585. Docking studies of the conjugates with the highest affinities support the conclusion that despite the various conjugations, the pleuomutilin skeleton binds in the same binding pocket. The conjugated triazole moiety is well accommodated, and the nucleobases are placed in different pockets in the 50S ribosomal subunit. The derivative showing the highest affinity and a significantly better binding than Pleuromutilin itself contains an adenine-9-ylpropylene triazole conjugate to Pleuromutilin C-22.

Sarah E. Reisman - One of the best experts on this subject based on the ideXlab platform.

  • Total Synthesis of (+)-Pleuromutilin
    Journal of the American Chemical Society, 2018
    Co-Authors: Elliot P. Farney, Sean S. Feng, Felix Schäfers, Sarah E. Reisman
    Abstract:

    An 18-step synthesis of the antibiotic (+)-Pleuromutilin is disclosed. The key steps of the synthesis include a highly stereoselective SmI2-mediated cyclization to establish the eight-membered ring and a stereospecific transannular [1,5]-hydrogen atom transfer to set the C10 stereocenter. This strategy was also used to prepare (+)-12-epi-Pleuromutilin. The chemistry described here will enable efforts to prepare new mutilin antibiotics.

  • total synthesis of Pleuromutilin
    Journal of the American Chemical Society, 2018
    Co-Authors: Elliot P. Farney, Sean S. Feng, Felix Schäfers, Sarah E. Reisman
    Abstract:

    An 18-step synthesis of the antibiotic (+)-Pleuromutilin is disclosed. The key steps of the synthesis include a highly stereoselective SmI2-mediated cyclization to establish the eight-membered ring and a stereospecific transannular [1,5]-hydrogen atom transfer to set the C10 stereocenter. This strategy was also used to prepare (+)-12-epi-Pleuromutilin. The chemistry described here will enable efforts to prepare new mutilin antibiotics.

  • Total Synthesis of (+)-Pleuromutilin
    2018
    Co-Authors: Elliot P. Farney, Sean S. Feng, Felix Schäfers, Sarah E. Reisman
    Abstract:

    An 18-step synthesis of the antibiotic (+)-Pleuromutilin is disclosed. The key steps of the synthesis include a highly stereoselective SmI2-mediated cyclization to establish the eight-membered ring and a stereospecific transannular [1,5]-hydrogen atom transfer to set the C10 stereocenter. This strategy was also used to prepare (+)-12-epi-Pleuromutilin. The chemistry described here will enable efforts to prepare new mutilin antibiotics