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William H. Gerwick - One of the best experts on this subject based on the ideXlab platform.
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Heterologous Production of 4-O-DemethylBarbamide, a Marine Cyanobacterial Natural Product
Organic letters, 2012Co-Authors: Eunji Kim, Jong-hyun Lee, Hyukjae Choi, Alban R. Pereira, Yeon Hee Ban, Young Ji Yoo, Je Won Park, David H. Sherman, William H. GerwickAbstract:Heterologous expression of the Barbamide biosynthetic gene cluster, obtained from the marine cyanobacterium Moorea producens, in the terrestrial actinobacterium Streptomyces venezuelae, resulted in the production of a new Barbamide congener 4-O-demethylBarbamide, demonstrating the potential of this approach for investigating the assembly and tailoring of complex marine natural products.
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Characterization of the initial enzymatic steps of Barbamide biosynthesis.
Journal of natural products, 2006Co-Authors: Patricia M. Flatt, Christine L. Willis, David H. Sherman, Susan J. O'connell, Kerry L. Mcphail, Gloria Zeller, William H. GerwickAbstract:Barbamide is a mixed polypeptide-polyketide natural product that contains an unusual trichloromethyl group. The origin of the trichloromethyl group was previously shown to be through chlorination of the pro-R methyl group of L-leucine. Trichloroleucine is subsequently decarboxylated and oxidized to trichloroisovaleric acid and then extended with an acetate unit to form the initial seven carbons of Barbamide. In this study we used a combination of biosynthetic feeding experiments and enzymatic analysis to characterize the initial steps required for formation of trichloroleucine and its chain-shortened product, trichloroisovaleric acid. Results from isotope-labeled feeding experiments showed that both dichloroleucine and trichloroleucine are readily incorporated into Barbamide; however, monochloroleucine is not. This suggests that halogenation of the pro-R methyl group of leucine occurs as two discrete reactions, with the first involving incorporation of at least two halogen atoms and the second converting dichloroleucine to trichloroleucine. Additionally, the initial tandem dichlorination must occur before substrate can be further processed by the remaining bar pathway enzymes. In vitro analysis of the first five open reading frames (ORFs; barA, barB1, barB2, bar C, barD) of the Barbamide gene cluster has yielded new insights into the processing of leucine to form the trichloroisovalerylderived unit in the final product.
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Identification of the cellular site of polychlorinated peptide biosynthesis in the marine sponge Dysidea (Lamellodysidea) herbacea and symbiotic cyanobacterium Oscillatoria spongeliae by CARD-FISH analysis
Marine Biology, 2005Co-Authors: Patricia M. Flatt, Jeffrey T. Gautschi, Robert W. Thacker, Mirjam Musafija-girt, Phillip Crews, William H. GerwickAbstract:Populations of the sponge Dysidea ( Lamellodysidea ) herbacea, which host the cyanobacterium Oscillatoria spongeliae , vary in their production of polychlorinated peptides. Peptide natural products previously isolated from D. herbacea are often halogenated and include dysidin, dysidinin, and a series of chlorinated diketopiperazines. Strikingly, the distinctive leucine-derived trichloromethyl signature of these compounds is shared only with metabolites of the marine cyanobacterium Lyngbya majuscula , and includes such compounds as Barbamide and nordysidinin. Genetic information available for the Barbamide biosynthetic gene cluster was used to successfully polymerase chain reaction (PCR) amplify a barB1 homolog ( dysB1 ) from D. herbacea samples collected in Papua New Guinea. Catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) analysis showed that dysB1 oligonucleotide probes hybridized to sequences in the filamentous cyanobacterial symbiont O. spongeliae. Consistent with this finding, a D. herbacea / O. spongeliae collection devoid of the polychlorinated peptides did not contain the barB1 homologs.
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[6-13C]-(2S, 4S)-5-chloroleucine: synthesis and incubation studies with cultures of the cyanobacterium, Lyngbya majuscula
Tetrahedron Letters, 2003Co-Authors: William H. Gerwick, Brian L. Marquez, Pauline Leslie, G. Cliona Long, Christine L. WillisAbstract:Abstract [6-13C]-(2S,4S)-5-Chloroleucine 12 was prepared in six steps and 26% overall yield from protected l -glutamic acid using 13CH3I as the source of isotopic label. On feeding 12 to cultures of L. majuscula no incorporation of isotopic label into the trichlorinated marine natural product Barbamide was detected. The synthesis of a novel dichloroleucine derivative 16 is also described.
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The Barbamide biosynthetic gene cluster: a novel marine cyanobacterial system of mixed polyketide synthase (PKS)-non-ribosomal peptide synthetase (NRPS) origin involving an unusual trichloroleucyl starter unit.
Gene, 2002Co-Authors: Zunxue Chang, William H. Gerwick, Viet-anh Nguyen, Christine L. Willis, Patricia Flatt, David H. ShermanAbstract:Barbamide was extracted from the marine cyanobacterium Lyngbya majuscula strain 19L as a chlorinated lipopeptide for its potent molluscicidal activity. Precursor incorporation studies indicated that it is derived from acetate, L-phenylalanine, L-leucine and L-cysteine. The gene cluster responsible for biosynthesis of Barbamide (bar) was cloned and characterized in this study. DNA sequence analysis of cosmid pLM49 revealed a cluster of 12 open reading frames (barA-barK) extending 26 kb including the expected polyketide synthase and non-ribosomal peptide synthetase modules and tailoring genes. The genetic architecture and domain organization of the bar cluster supports the assignment based on the apparent co-linearity of the systems. The activity assay of adenylation domains of barD (A(D)), barE (A(E)) and barG (A(G2) for module 2) in an amino acid-dependent ATP-pyrophosphate exchange experiment supports the conclusion that Barbamide is synthesized from acetate, L-phenylalanine, L-cysteine and L-leucine with trichloroleucine as a direct precursor by a mixed polyketide synthase/non-ribosomal polypeptide synthetase. Assembly of Barbamide includes unique biochemical mechanisms for chlorination, one-carbon truncation during chain elongation, E-double bond formation and thiazole ring formation.
Christine L. Willis - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the initial enzymatic steps of Barbamide biosynthesis.
Journal of natural products, 2006Co-Authors: Patricia M. Flatt, Christine L. Willis, David H. Sherman, Susan J. O'connell, Kerry L. Mcphail, Gloria Zeller, William H. GerwickAbstract:Barbamide is a mixed polypeptide-polyketide natural product that contains an unusual trichloromethyl group. The origin of the trichloromethyl group was previously shown to be through chlorination of the pro-R methyl group of L-leucine. Trichloroleucine is subsequently decarboxylated and oxidized to trichloroisovaleric acid and then extended with an acetate unit to form the initial seven carbons of Barbamide. In this study we used a combination of biosynthetic feeding experiments and enzymatic analysis to characterize the initial steps required for formation of trichloroleucine and its chain-shortened product, trichloroisovaleric acid. Results from isotope-labeled feeding experiments showed that both dichloroleucine and trichloroleucine are readily incorporated into Barbamide; however, monochloroleucine is not. This suggests that halogenation of the pro-R methyl group of leucine occurs as two discrete reactions, with the first involving incorporation of at least two halogen atoms and the second converting dichloroleucine to trichloroleucine. Additionally, the initial tandem dichlorination must occur before substrate can be further processed by the remaining bar pathway enzymes. In vitro analysis of the first five open reading frames (ORFs; barA, barB1, barB2, bar C, barD) of the Barbamide gene cluster has yielded new insights into the processing of leucine to form the trichloroisovalerylderived unit in the final product.
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[6-13C]-(2S, 4S)-5-chloroleucine: synthesis and incubation studies with cultures of the cyanobacterium, Lyngbya majuscula
Tetrahedron Letters, 2003Co-Authors: William H. Gerwick, Brian L. Marquez, Pauline Leslie, G. Cliona Long, Christine L. WillisAbstract:Abstract [6-13C]-(2S,4S)-5-Chloroleucine 12 was prepared in six steps and 26% overall yield from protected l -glutamic acid using 13CH3I as the source of isotopic label. On feeding 12 to cultures of L. majuscula no incorporation of isotopic label into the trichlorinated marine natural product Barbamide was detected. The synthesis of a novel dichloroleucine derivative 16 is also described.
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The Barbamide biosynthetic gene cluster: a novel marine cyanobacterial system of mixed polyketide synthase (PKS)-non-ribosomal peptide synthetase (NRPS) origin involving an unusual trichloroleucyl starter unit.
Gene, 2002Co-Authors: Zunxue Chang, William H. Gerwick, Viet-anh Nguyen, Christine L. Willis, Patricia Flatt, David H. ShermanAbstract:Barbamide was extracted from the marine cyanobacterium Lyngbya majuscula strain 19L as a chlorinated lipopeptide for its potent molluscicidal activity. Precursor incorporation studies indicated that it is derived from acetate, L-phenylalanine, L-leucine and L-cysteine. The gene cluster responsible for biosynthesis of Barbamide (bar) was cloned and characterized in this study. DNA sequence analysis of cosmid pLM49 revealed a cluster of 12 open reading frames (barA-barK) extending 26 kb including the expected polyketide synthase and non-ribosomal peptide synthetase modules and tailoring genes. The genetic architecture and domain organization of the bar cluster supports the assignment based on the apparent co-linearity of the systems. The activity assay of adenylation domains of barD (A(D)), barE (A(E)) and barG (A(G2) for module 2) in an amino acid-dependent ATP-pyrophosphate exchange experiment supports the conclusion that Barbamide is synthesized from acetate, L-phenylalanine, L-cysteine and L-leucine with trichloroleucine as a direct precursor by a mixed polyketide synthase/non-ribosomal polypeptide synthetase. Assembly of Barbamide includes unique biochemical mechanisms for chlorination, one-carbon truncation during chain elongation, E-double bond formation and thiazole ring formation.
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Synthesis of the marine natural product Barbamide
Chemical communications (Cambridge England), 2001Co-Authors: Viet-anh Nguyen, Christine L. Willis, William H. GerwickAbstract:The first total synthesis of the trichlorinated natural product Barbamide is described. The convergent approach involves coupling (S)-3-trichloromethylbutanoyl chloride with Meldrum’s acid (2,2-dimethyl-1,3-dioxane-4,6-dione) to give 15 followed by addition of the novel secondary amine N-methyl-(S)-dolaphenine 2 (prepared in 6 steps and 24% overall yield from N-Cbz-L-phenylalanine) to give the β-keto amide 16 which was converted directly to the required (E)-enol ether.
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Biosynthetic Pathway and Origin of the Chlorinated Methyl Group in Barbamide and DechloroBarbamide, Metabolites from the Marine Cyanobacterium Lyngbya majuscula
Tetrahedron, 2000Co-Authors: Namthip Sitachitta, Brian L. Marquez, R. Thomas Williamson, James Rossi, Mary Ann Roberts, William H. Gerwick, Viet-anh Nguyen, Christine L. WillisAbstract:Abstract Structural and biosynthetic studies have been conducted on the Barbamide class of molluscicidal agent. DechloroBarbamide was isolated from a Curacao collection of the marine cyanobacterium Lyngbya majuscula and its structure determined through spectroscopic analysis and comparisons with Barbamide. The absolute stereochemistry of the dolaphenine moiety of Barbamide was determined to be S , defining the absolute configuration of Barbamide as 2 S ,7 S . Stable isotope feeding experiments conducted with cultured L. majuscula have provided clear evidence that Barbamide biosynthesis involves chlorination of the unactivated pro - R methyl group of leucine. Experiments with l -[ 2 H 10 ]leucine demonstrated that chlorination of the pro- R methyl occurs without detectable activation via the leucine-catabolic pathway. Moreover, an extremely high level of incorporation of fed [2- 13 C]-5,5,5-trichloroleucine into Barbamide indicates that leucine is the probable substrate for the chlorination reaction. Incorporations of [1,2- 13 C 2 ]acetate and [1- 13 C, 1- 18 O]acetate confirmed the origins of C-5 and C-6 whereas incorporation of l -[3- 13 C]phenylalanine supported the hypothesis that the phenyl group and its three carbon side-chain in Barbamide (C-7, C-8 and C-10–C-16) arise from phenylalanine. The thiazole ring (C-17–C-18) of 1 was shown to likely arise from cysteine through a [2- 13 C, 15 N]glycine feeding experiment. Detection of intact 13 C– 15 N bond was observed by application of a new GHNMBC NMR experiment. Results from this latter feeding experiment also indicated that the N–CH 3 and O–CH 3 groups of 1 originate from the C 1 pool; this was supported by enrichment in these methyl groups when cultures were provided with l -[methyl- 13 C]methionine.
Eunji Kim - One of the best experts on this subject based on the ideXlab platform.
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Heterologous Production of 4-O-DemethylBarbamide, a Marine Cyanobacterial Natural Product
Organic letters, 2012Co-Authors: Eunji Kim, Jong-hyun Lee, Hyukjae Choi, Alban R. Pereira, Yeon Hee Ban, Young Ji Yoo, Je Won Park, David H. Sherman, William H. GerwickAbstract:Heterologous expression of the Barbamide biosynthetic gene cluster, obtained from the marine cyanobacterium Moorea producens, in the terrestrial actinobacterium Streptomyces venezuelae, resulted in the production of a new Barbamide congener 4-O-demethylBarbamide, demonstrating the potential of this approach for investigating the assembly and tailoring of complex marine natural products.
Jens Hartung - One of the best experts on this subject based on the ideXlab platform.
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The Biosynthesis of Barbamide-A Radical Pathway for "Biohalogenation"?
Angewandte Chemie (International ed. in English), 1999Co-Authors: Jens HartungAbstract:A stereoselective chlorination of a methyl group and the preference of cleavage of nonactivated primary C-H bonds in one of the methyl groups with respect to a weaker tertiary C-H bond in the course of the biosynthesis of Barbamide point to a surprising, new mechanism of "biohalogenation" (see schematic diagram).
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the biosynthesis of Barbamide a radical pathway for biohalogenation
Angewandte Chemie, 1999Co-Authors: Jens HartungAbstract:A stereoselective chlorination of a methyl group and the preference of cleavage of nonactivated primary C-H bonds in one of the methyl groups with respect to a weaker tertiary C-H bond in the course of the biosynthesis of Barbamide point to a surprising, new mechanism of "biohalogenation" (see schematic diagram).
Brett A. Neilan - One of the best experts on this subject based on the ideXlab platform.
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The genetics, biosynthesis and regulation of toxic specialized metabolites of cyanobacteria.
Harmful Algae, 2016Co-Authors: Leanne A. Pearson, Sarah E. Ongley, Elke Dittmann, Rabia Mazmouz, Paul M. D’agostino, Brett A. NeilanAbstract:The production of toxic metabolites by cyanobacterial blooms represents a significant threat to the health of humans and ecosystems worldwide. Here we summarize the current state of the knowledge regarding the genetics, biosynthesis and regulation of well-characterized cyanotoxins, including the microcystins, nodularin, cylindrospermopsin, saxitoxins and anatoxins, as well as the lesser-known marine toxins (e.g. lyngbyatoxin, aplysiatoxin, jamaicamides, Barbamide, curacin, hectochlorin and apratoxins).