The genome of a saxitoxin-producing cyanobacterium

Abstract

Saxitoxin, the causative agent of paralytic shellfish poisoning, is produced by dinoflagellates and cyanobacteria, the latter being a far simpler organism at the genomic level. In order to establish a baseline for future research into saxitoxin biosynthesis, we sought to determine the genomic complexity of the saxitoxin-producing cyanobacterium, Anabaena circinalis strain ACBU02, relative to the published genome of its non-toxic analogue, Anabaena sp. PCC 7120. Total conservation of genomic organization was represented in less than 10 percent of end-sequenced DNA clones from restriction digestion libraries. Ninety percent of sequences contained highly homologous regions indicating a high degree of conservation among genome content. The genome size of A. circinalis strain ACBU02 was also estimated to be significantly smaller than that of Anabaena sp. PCC 7120. These data provide a solid foundation for the development of new strategies for isolation of the genes responsible for biosynthesis of saxitoxin and its chemically similar congeners from saxitoxin-producing cyanobacteria.