Luminmycins A–C, Cryptic Natural Products from Photorhabdus luminescens Identified by Heterologous Expression in Escherichia coli

The 18 kb "silent" luminmycin biosynthetic pathway from Photorhabdus luminescens was cloned into a vector by using the newly established linear-linear homologous recombination and successfully expressed in Escherichia coli. Luminmycins A-C (1-3) were isolated from the heterologous host, and their structures were elucidated using 2D NMR spectroscopy and HRESIMS. Luminmycin A is a deoxy derivative of the previously reported glidobactin A, while luminmycins B and C most likely represent its acyclic biosynthetic intermediates. Compound 1 showed cytotoxicity against the human colon carcinoma HCT-116 cell line with an IC(50) value of 91.8 nM, while acyclic 2 was inactive at concentrations as high as 100 μg/mL.