Heterologous Expression of an Unusual Ketosynthase, SxtA, Leads to Production of Saxitoxin Intermediates in Escherichia coli
| Autor: | Bakir Al-Sinawi, Ralf Kellmann, Brett A. Neilan, Angela H. Soeriyadi, Russell Pickford, Rabia Mazmouz, Leanne A. Pearson |
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| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
Saxitoxin Ketone Organic Chemistry Voltage-Gated Sodium Channels medicine.disease_cause medicine.disease Biochemistry Poisons Substrate Specificity chemistry.chemical_compound Polyketide Enzyme Biosynthesis chemistry Escherichia coli medicine Molecular Medicine Heterologous expression Paralytic shellfish poisoning Molecular Biology Cylindrospermopsis |
| Zdroj: | ChemBioChem. 22:845-849 |
| ISSN: | 1439-7633 1439-4227 |
| DOI: | 10.1002/cbic.202000675 |
| Popis: | Paralytic shellfish toxins (PSTs) are neurotoxic alkaloids produced by freshwater cyanobacteria and marine dinoflagellates. Due to their antagonism of voltage-gated sodium channels in excitable cells, certain analogues are of significant pharmacological interest. The biosynthesis of the parent compound, saxitoxin, is initiated with the formation of 4-amino-3-oxo-guanidinoheptane (ethyl ketone) by an unusual polyketide synthase-like enzyme, SxtA. We have heterologously expressed SxtA from Raphidiopsis raciborskii T3 in Escherichia coli and analysed its activity in vivo. Ethyl ketone and a truncated analogue, methyl ketone, were detected by HPLC-ESI-HRMS analysis, thus suggesting that SxtA has relaxed substrate specificity in vivo. The chemical structures of these products were further verified by tandem mass spectrometry and labelled-precursor feeding with [guanidino-15 N2 ] arginine and [1,2-13 C2 ] acetate. These results indicate that the reactions catalysed by SxtA could give rise to multiple PST variants, including analogues of ecological and pharmacological significance. |
| Databáze: | OpenAIRE |
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