Cylindrospermopsin and Saxitoxin Biosynthesis

The present study deals with the molecular genetics and biochemistry of two cyanobacterial toxins, cylindrospermopsin and saxitoxin. The molecular phylogenies of three putative cylindrospermopsin biosynthesis genes, encoding an amidinotransferase (aoaA), a non-ribosomal peptide synthetase (aoaB) and a polyketide synthase (aoaC) has been examined and functional modelling was carried out to gain insights into the mechanism of precursor recruitment in this pathway. An in vitro assay was developed to characterise biochemical requirements for saxitoxin biosynthesis, using enzyme extracts from Cylindrospermopsis raciborskii T3. All biosynthesis enzymes were located in the cytosol. The effects of substrates and inhibitors on the in vitro biosynthesis of saxitoxin were examined and predictions made regarding enzymes that may be involved. These predictions were used in a degenerate PCR approach to identify the saxitoxin biosynthesis gene cluster in cyanobacteria.

Autorentext

Dr. Ralf Kellmann has obtained his MSc in Marine Science at Otago University, NZ (1999), and his PhD in Microbiology at the Univerversity of NSW, AU (2005). He has over 15 years of research experience on algal toxins. Currently he is working as a method developer for the LC-MS analysis of hormones and drugs at the Haukeland University Hospital.