Pyrrolo[1,4]benzodiazepine antibiotics. Biosynthesis of the antitumor antibiotic sibiromycin by Streptosporangium sibiricum

Hurley, Laurence H.; Lasswell, William L.; Malhotra, Ravinder; Das, Nobel V.

doi:10.1021/bi00586a029

Cited by 18 publications

(23 citation statements)

References 14 publications

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“…Growth and maintenance of S. sibiricum (DSM 44039) were performed as described by Hurley et al (14) using mycelial plugs. The plugs were prepared routinely every 2 months due to the previously observed loss of antibiotic production (14) 3 ) with previously prepared plugs accounting for 2% of the total volume. Flasks were shaken at 250 rpm and at 30°C for 84 h. Optimal aeration was obtained by using flasks with springs and by filling a maximum one-fifth of the flask volume with medium.…”

Section: Methodsmentioning

confidence: 99%

“…A 2% inoculum of mycelial plugs of wild-type and mutant S. sibiricum strains was added to flasks with springs filled up to one-fifth of the total volume with the sibiromycin medium described above. Flasks were shaken at 250 rpm and 30°C for 60 h. Sibiromycin was isolated by using a modified protocol described by Hurley et al (14). Production growths were extracted three times with equal volumes of dichloromethane.…”

Section: Methodsmentioning

confidence: 99%

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Biosynthesis of Sibiromycin, a Potent Antitumor Antibiotic

Khullar

Chou

et al. 2009

Appl Environ Microbiol

116

159

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Pyrrolobenzodiazepines, a class of natural products produced by actinomycetes, are sequence selective DNA alkylating compounds with significant antitumor properties. Among the pyrrolo[1,4]benzodiazepines (PBDs) sibiromycin, one of two identified glycosylated PBDs, displays the highest affinity for DNA and the most potent antitumor properties. Despite the promising antitumor properties clinical trials of sibiromycin were precluded by the cardiotoxicity effect in animals attributed to the presence of the C-9 hydroxyl group. As a first step toward the development of sibiromycin analogs, we have cloned and localized the sibiromycin gene cluster to a 32.7-kb contiguous DNA region. Cluster boundaries tentatively assigned by comparative genomics were verified by gene replacement experiments. The sibiromycin gene cluster consisting of 26 open reading frames reveals a "modular" strategy in which the synthesis of the anthranilic and dihydropyrrole moieties is completed before assembly by the nonribosomal peptide synthetase enzymes. In addition, the gene cluster identified includes open reading frames encoding enzymes involved in sibirosamine biosynthesis, as well as regulatory and resistance proteins. Gene replacement and chemical complementation studies are reported to support the proposed biosynthetic pathway.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Biosynthesis of Sibiromycin, a Potent Antitumor Antibiotic

Khullar

Chou

et al. 2009

Appl Environ Microbiol

116

159

View full text Add to dashboard Cite

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“…To test whether the K. oxytoca toxin belongs to the PBD substance class we purified and determined its structure. We applied conventional extraction methods for PBDs (35,36) to conditioned media of AHC-6 wild-type strain and the ΔnpsA mutant. HPLC-MS analysis identified a 333-Da substance exclusively present in the extract of AHC-6 (Fig.…”

Section: Significancementioning

confidence: 99%

Enterotoxicity of a nonribosomal peptide causes antibiotic-associated colitis

Schneditz

Rentner

Roier

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

103

181

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Antibiotic therapy disrupts the human intestinal microbiota. In some patients rapid overgrowth of the enteric bacterium Klebsiella oxytoca results in antibiotic-associated hemorrhagic colitis (AAHC). We isolated and identified a toxin produced by K. oxytoca as the pyrrolobenzodiazepine tilivalline and demonstrated its causative action in the pathogenesis of colitis in an animal model. Tilivalline induced apoptosis in cultured human cells in vitro and disrupted epithelial barrier function, consistent with the mucosal damage associated with colitis observed in human AAHC and the corresponding animal model. Our findings reveal the presence of pyrrolobenzodiazepines in the intestinal microbiota and provide a mechanism for colitis caused by a resident pathobiont. The data link pyrrolobenzodiazepines to human disease and identify tilivalline as a target for diagnosis and neutralizing strategies in prevention and treatment of colitis.bacteria | enteric microbiota | cytotoxin

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“…+> Thus mechanisms including the NIH-shift are discussed within the biosynthesis of pyrrolo benzodiazepines from actinomycetes and streptomycetes [32][33][34] and of benzodiazepine alkaloides from Penicillium cyclopium [35]. …”

Section: Metabolite M 14mentioning

confidence: 99%

Metabolism and pharmacokinetics of metaclazepam (Talis®), Part III: Determination of the chemical structure of metabolites in dogs, rabbits and men

Borchers¹,

Achtert²,

Hausleiter³

et al. 1984

European Journal of Drug Metabolism and Pharmacokinetics

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The metabolism of 7-bromo-1-methyl-2-methoxymethyl-5-(2'-chlorophenyl)-2, 3-dihydro-1H-1,4-benzodiazepine (metaclazepam, Talis) in animals and men is described. Based upon mass spectrometry fifteen metabolites could be identified. Qualitative and quantitative differences in the biotransformation products of metaclazepam in comparison with the well known metabolites of other drugs in the 1,4-benzodiazepine class could be demonstrated. Metabolites with a benzodiazepine-2-one structure representing the most characteristic feature of other 1,4-benzodiazepines and their metabolites, were found in trace amounts only. The major metabolic pathways of metaclazepam led via stepwise demethylation of the O-methyl and/or the N-methyl group to O-demethyl-metaclazepam (M 2), N-demethyl-metaclazepam (M 7) and bis-demethyl-metaclazepam (M 6). Further aromatic hydroxylation yielded the metabolite M 1. Two metabolites with amino-benzophenone structure (M 5, M 8) which are in general known to result from other 1,4-benzodiazepines could be detected. Additionally a 3-oxo-benzodiazepine (M 4) was found. Minor biotransformation pathways led to a chlorophenyl-bromo-benzodiazepine (M 9) by loss of the side chain from bis-demethyl-metaclazepam and N-demethyl-metaclazepam. By further oxidation and degradation the 2-oxo-benzodiazepine M 10 and the dihydro-quinazoline M 12 were formed. The respective N-methylated metabolites M 13 and M 16 were possibly generated by the same pathway. Still open is the formation of M 15, a 1-methyl-3-hydroxy-4-(2'-chlorophenyl)-6-bromo-1,2-dihydroquinoline and M 11, a 2-methyl-4-(2'-chlorophenyl)-6-bromo-quinazoline. The substitution of bromine by a hydroxyl group during the formation of M 14 can be explained by a NIH-shift mechanism. Quantitative investigations show that the methoxymethyl side chain in the benzodiazepine ring system of metaclazepam acts as an effective barrier with respect to the metabolic attack at position two. We assume that this barrier only can be overcome by complete side chain degradation. This multi-step reaction can hardly compete with more favourable and faster conjugation and elimination processes.

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Pyrrolo[1,4]benzodiazepine antibiotics. Biosynthesis of the antitumor antibiotic sibiromycin by Streptosporangium sibiricum

Cited by 18 publications

References 14 publications

Biosynthesis of Sibiromycin, a Potent Antitumor Antibiotic

Biosynthesis of Sibiromycin, a Potent Antitumor Antibiotic

Enterotoxicity of a nonribosomal peptide causes antibiotic-associated colitis

Metabolism and pharmacokinetics of metaclazepam (Talis®), Part III: Determination of the chemical structure of metabolites in dogs, rabbits and men

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