Biosynthetic route towards saxitoxin and shunt pathway
Saxitoxin, the most potent voltage-gated sodium channel blocker, is one of the paralytic shellfish toxins (PSTs) produced by cyanobacteria and dinoflagellates. Recently, putative biosynthetic genes of PSTs were reported in these microorganisms. We previously synthesized genetically predicted biosynt...
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Veröffentlicht in: | Scientific reports 2016-02, Vol.6 (1), p.20340-20340, Article 20340 |
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Zusammenfassung: | Saxitoxin, the most potent voltage-gated sodium channel blocker, is one of the paralytic shellfish toxins (PSTs) produced by cyanobacteria and dinoflagellates. Recently, putative biosynthetic genes of PSTs were reported in these microorganisms. We previously synthesized genetically predicted biosynthetic intermediates, Int-A’ and Int-C’2 and also Cyclic-C’ which was not predicted based on gene and identified them all in the toxin-producing cyanobacterium
Anabaena circinalis
(TA04) and the dinoflagellate
Alexandrium tamarense
(Axat-2). This study examined the incorporation of
15
N-labeled intermediates into PSTs (C1 and C2) in
A. circinalis
(TA04). Conversions from Int-A’ to Int-C’2, from Int-C’2 to Cyclic-C’ and from Int-A’ and Int-C’2 to C1 and C2 were indicated using high resolution-LC/MS. However, Cyclic-C’ was not converted to C1 and C2 and was detected primarily in the extracellular medium. These results suggest that Int-A’ and Int-C’2 are genuine precursors of PSTs, but Int-C’2 converts partially to Cyclic-C’ which is a shunt product excreted to outside the cells. This paper provides the first direct demonstration of the biosynthetic route towards saxitoxin and a shunt pathway. |
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ISSN: | 2045-2322 2045-2322 |
DOI: | 10.1038/srep20340 |