Structure and Biosynthetic Assembly of Piscibactin, a Siderophore from Photobacterium damselae subsp piscicida, Predicted from Genome Analysis

From the cultures of Photobacterium damselae subsp. piscicida, the aetiological agent of fish pasteurellosis, a new siderophore named piscibactin (1), was isolated as its gallium and iron(III) complexes along with a possible intermediate of its biosynthesis, prepiscibactin (2). Analysis of the gene cluster involved in the siderophore biosynthesis allowed the partial prediction of the structures. Thus, an NRPS-mediated mechanism similar to that for yersiniabactin was suggested by protein sequence comparisons. The final structures were solved by NMR and MS methods and by DFT molecular modeling. The results obtained in the structural and functional characterization of piscibactin enabled the proposal of a biosynthetic pathway.