Rearranged Biosynthetic Gene Cluster and Synthesis of Hassallidin E in Planktothrix serta PCC 8927

5 years ago

Rearranged Biosynthetic Gene Cluster and Synthesis of Hassallidin E in Planktothrix serta PCC 8927

Nathalie Sassoon, Marie Desnos-Ollivier, Alexandra Calteau, Kaarina Sivonen, Anu Humisto, Sylvie Bay, Claire Pancrace, Muriel Gugger, David P. Fewer, Matti Wahlsten, Jouni Jokela, Christelle Ganneau

Cyanobacteria produce a wide range of natural products with antifungal bioactivity. The cyclic glycosylated lipopeptides of the hassallidin family have potent antifungal activity and display a great degree of chemical diversity. Here, we report the discovery of a hassallidin biosynthetic gene cluster from the filamentous cyanobacterium Planktothrix serta PCC 8927. The hassallidin gene cluster showed heavy rearrangement and marks of genomic plasticity. Nucleotide bias, differences in GC content, and phylogenetic incongruence suggested the acquisition of the hassallidin biosynthetic gene cluster in Planktothrix serta PCC 8927 by horizontal gene transfer. Chemical analyses by liquid chromatography and mass spectrometry demonstrated that this strain produced hassallidin E, a new glycosylated hassallidin variant. Hassallidin E was the only structural variant produced by Planktothrix serta PCC 8927 in all tested conditions. Further evaluated on human pathogenic fungi, hassallidin E showed an antifungal bioactivity. Hassallidin production levels correlated with nitrogen availability, in the only nitrogen-fixing Planktothrix described so far. Our results provide insights into the distribution and chemical diversity of cyanobacterial antifungal compounds as well as raise questions on their ecological relevance.

Publisher URL: http://dx.doi.org/10.1021/acschembio.7b00093

DOI: 10.1021/acschembio.7b00093