Nejvíce citovaný článek - PubMed ID 21030245
Cyanobacteria are infamous producers of toxins. While the toxic potential of planktonic cyanobacterial blooms is well documented, the ecosystem level effects of toxigenic benthic and epiphytic cyanobacteria are an understudied threat. The freshwater epiphytic cyanobacterium Aetokthonos hydrillicola has recently been shown to produce the "eagle killer" neurotoxin aetokthonotoxin (AETX) causing the fatal neurological disease vacuolar myelinopathy. The disease affects a wide array of wildlife in the southeastern United States, most notably waterfowl and birds of prey, including the bald eagle. In an assay for cytotoxicity, we found the crude extract of the cyanobacterium to be much more potent than pure AETX, prompting further investigation. Here, we describe the isolation and structure elucidation of the aetokthonostatins (AESTs), linear peptides belonging to the dolastatin compound family, featuring a unique modification of the C-terminal phenylalanine-derived moiety. Using immunofluorescence microscopy and molecular modeling, we confirmed that AEST potently impacts microtubule dynamics and can bind to tubulin in a similar matter as dolastatin 10. We also show that AEST inhibits reproduction of the nematode Caenorhabditis elegans. Bioinformatic analysis revealed the AEST biosynthetic gene cluster encoding a nonribosomal peptide synthetase/polyketide synthase accompanied by a unique tailoring machinery. The biosynthetic activity of a specific N-terminal methyltransferase was confirmed by in vitro biochemical studies, establishing a mechanistic link between the gene cluster and its product.
- Klíčová slova
- aetokthonostatin, biosynthesis, cyanotoxin, cytotoxicity, dolastatin,
- MeSH
- Accipitridae * MeSH
- Caenorhabditis elegans MeSH
- ekosystém MeSH
- sinice * genetika MeSH
- sladká voda MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aetokthonotoxin MeSH Prohlížeč
Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species Aetokthonos hydrillicola growing on aquatic vegetation, primarily the invasive Hydrilla verticillata Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium A. hydrillicola We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors-especially bromide availability-that promote toxin production.
- MeSH
- Accipitridae * MeSH
- bakteriální geny MeSH
- bakteriální toxiny biosyntéza chemie izolace a purifikace toxicita MeSH
- brom analýza MeSH
- bromidy metabolismus MeSH
- Caenorhabditis elegans účinky léků MeSH
- dánio pruhované MeSH
- demyelinizační nemoci chemicky indukované veterinární MeSH
- Hydrocharitaceae metabolismus mikrobiologie MeSH
- indolové alkaloidy chemie izolace a purifikace toxicita MeSH
- kur domácí MeSH
- LD50 MeSH
- multigenová rodina MeSH
- nemoci ptáků chemicky indukované MeSH
- neurotoxiny biosyntéza chemie izolace a purifikace toxicita MeSH
- sinice * genetika růst a vývoj metabolismus MeSH
- tryptofan metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, P.H.S. MeSH
- Geografické názvy
- jihovýchod USA MeSH
- Názvy látek
- bakteriální toxiny MeSH
- brom MeSH
- bromidy MeSH
- indolové alkaloidy MeSH
- neurotoxiny MeSH
- tryptofan MeSH
Heterocytous cyanobacteria are among the most prolific sources of bioactive secondary metabolites, including anabaenopeptins (APTs). A terrestrial filamentous Brasilonema sp. CT11 collected in Costa Rica bamboo forest as a black mat, was studied using a multidisciplinary approach: genome mining and HPLC-HRMS/MS coupled with bioinformatic analyses. Herein, we report the nearly complete genome consisting of 8.79 Mbp with a GC content of 42.4%. Moreover, we report on three novel tryptophan-containing APTs; anabaenopeptin 788 (1), anabaenopeptin 802 (2), and anabaenopeptin 816 (3). Furthermore, the structure of two homologues, i.e., anabaenopeptin 802 (2a) and anabaenopeptin 802 (2b), was determined by spectroscopic analysis (NMR and MS). Both compounds were shown to exert weak to moderate antiproliferative activity against HeLa cell lines. This study also provides the unique and diverse potential of biosynthetic gene clusters and an assessment of the predicted chemical space yet to be discovered from this genus.
- Klíčová slova
- Brasilonema, anabaenopeptins, antiproliferative activity, hexapeptides, molecular networking, tryptophan-containing peptides,
- MeSH
- cyklické peptidy * chemie genetika izolace a purifikace farmakologie MeSH
- HeLa buňky MeSH
- hmotnostní spektrometrie MeSH
- lidé MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- proliferace buněk účinky léků MeSH
- sinice * chemie genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cyklické peptidy * MeSH
The rapid emergence of resistance in pathogenic bacteria together with a steep decline in economic incentives has rendered a new wave in the drug development by the pharmaceutical industry and researchers. Since cyanobacteria are recognized as wide producers of pharmaceutically important compounds, we investigated thirty-four cyanobacterial extracts prepared by solvents of different polarities for their antimicrobial potential. Almost all tested cyanobacterial strains exhibited some degree of antimicrobial bioactivity, with more general effect on fungal strains compared with bacteria. Surprisingly ~50% of cyanobacterial extracts exhibited specific activity against one or few bacterial indicator strains with Gram-positive bacteria being more affected. Extracts of two most promising strains were subjected to activity-guided fractionation and determination of the minimum inhibitory concentration (MIC) against selected bacterial and fungal isolates. Multiple fractions were responsible for their antimicrobial effect with MIC reaching low-micromolar concentrations and in some of them high level of specificity was recorded. Twenty-six bioactive fractions analyzed on LC-HRMS/MS and Global Natural Product Social Molecular Networking (GNPS) online workflow using dereplication resulted in identification of only forty-nine peptide spectrum matches (PSMs) with eleven unique metabolites spectrum matches (MSMs). Interestingly, only three fractions from Nostoc calcicola Lukešová 3/97 and four fractions from Desmonostoc sp. Cc2 showed the presence of unique MSMs suggesting the presence of unknown antimicrobial metabolites among majority of bioactive fractions from both the strains. Our results highlight potential for isolation and discovery of potential antimicrobial bioactive lead molecules from cyanobacterial extracts.
