Anacyclamide D8P, a prenylated cyanobactin from a Sphaerospermopsis sp. cyanobacterium

Cyanobactins are a family of linear and cyclic peptides produced through the post-translational modification of short precursor peptides. Anacyclamides are macrocyclic cyanobactins with a highly diverse sequence that are common in the genus <i>Anabaena</i>. A mass spectrometry-based screening of potential cyanobactin producers led to the discovery of a new prenylated member of this family of compounds, anacyclamide D8P (<b>1</b>), from <i>Sphaerospermopsis</i> sp. LEGE 00249. The anacyclamide biosynthetic gene cluster (<i>acy</i>) encoding the novel macrocyclic prenylated cyanobactin, was sequenced. Heterologous expression of the acy gene cluster in <i>Escherichia</i> <i>coli</i> established the connection between genomic and mass spectrometric data. Unambiguous establishment of the type and site of prenylation required the full structural elucidation of <b>1</b> using Nuclear Magnetic Resonance (NMR), which demonstrated that a forward prenylation occurred on the tyrosine residue. Compound <b>1</b> was tested in pharmacologically or ecologically relevant biological assays and revealed moderate antimicrobial activity towards the fouling bacterium <i>Halomonas aquamarina</i> CECT 5000.<br>