Biosynthetic Dynamics of Paralytic Shellfish Toxins in Dinoflagellates

Paralytic shellfish toxins (PSTs) are a suite of potent neurotoxins produced by various dinoflagellate species, notably within the genera Alexandrium, Gymnodinium and Pyrodinium. These alkaloid compounds, of which saxitoxin is the most emblematic, interfere with voltage-gated sodium channels in nerve and muscle cells, posing risks to marine ecosystems, aquaculture and public health. PST biosynthesis in dinoflagellates involves a modular pathway of enzymatic transformations encoded by nuclear genes of complex organisation, often present in multiple copies and regulated by both transcriptional and post-transcriptional mechanisms. Recent advances in molecular genetics, high-throughput sequencing and metabolomics have begun to unravel the timing and regulation of key biosynthetic steps, the influence of environmental parameters such as nutrients and temperature, and the evolutionary origin of toxin gene clusters. Interactions between gene dosage, transcript variants and metabolite flux underpin the dynamic regulation of toxin production during bloom events, offering new avenues for monitoring, prediction and mitigation of harmful algal blooms.

Research from Nature Portfolio

Investigations into the incorporation of isotopically labelled intermediates have provided the first direct demonstration of a defined biosynthetic route towards saxitoxin and a parallel shunt pathway. In this work, two nitrogen-labelled precursors were supplied to both a cyanobacterial model and a toxin-producing dinoflagellate, revealing sequential conversions through authentic intermediates Int-A′ and Int-C′2 en route to gonyautoxin analogues. A portion of Int-C′2 was diverted into a cyclised by-product, which was excreted rather than further transformed, thereby confirming the existence of a regulated shunt. These findings establish genuine precursors of PSTs in dinoflagellates and demonstrate how branching reactions may modulate toxin yield under varying cellular conditions.

Biosynthetic Dynamics of Paralytic Shellfish Toxins in Dinoflagellates publication trend

The graph below shows the total number of articles in biosynthetic dynamics of paralytic shellfish toxins in dinoflagellates across all publications each year (not limited to Nature Index journals).

Technical terms

Paralytic shellfish toxins (PSTs): A family of alkaloid neurotoxins that block voltage-gated sodium channels, causing paralytic shellfish poisoning.

Saxitoxin: The principal PST analogue and most potent natural blocker of voltage-gated sodium channels.

Dinoflagellates: A group of unicellular marine protists, many of which form harmful algal blooms and produce secondary metabolites.

Copy number variability (CNV): Differences in the number of copies of a particular gene within genomes of different strains or species.

Omics technologies: High-throughput approaches (genomics, transcriptomics, proteomics, metabolomics) used to study biological systems comprehensively.

References

1. Genomic copy number variability at the genus, species and population levels impacts in situ ecological analyses of dinoflagellates and harmful algal blooms. ISME Communications (2023).
2. The Genetic Basis of Toxin Biosynthesis in Dinoflagellates. Microorganisms (2019).
3. Biosynthesis of Saxitoxin in Marine Dinoflagellates: An Omics Perspective. Marine Drugs (2020).
4. Biosynthetic route towards saxitoxin and shunt pathway. Scientific Reports (2016).