Structure and biosynthetic assembly of cupriachelin, a photoreactive siderophore from the bioplastic producer Cupriavidus necator H16.

The bacterium Cupriavidus necator H16 produces a family of linear lipopeptides when grown under low iron conditions. The structural composition of these molecules, exemplified by the main metabolite cupriachelin, is reminiscent of siderophores that are excreted by marine bacteria. Comparable to marine siderophores, the ferric form of cupriachelin exhibits photoreactive properties. Exposure to UV light induces an oxidation of its peptidic backbone and a concomitant reduction of the coordinated Fe(III). Here, we report the genomics-inspired isolation and structural characterization of cupriachelin as well as its encoding gene cluster, which was identified by insertional mutagenesis. Based upon the functional characterization of adenylation domain specificity, a model for cupriachelin biosynthesis is proposed.