Discovery of a New Polycyclic Tetramate Macrolactam Clifednamide K

The artificial hybrid polycyclic tetramate macrolactam (PoTeM) gene cluster was constructed through combinatory biosynthesis approach and two PoTeMs, preikarugamycin (1) and clifednamide K (2), were isolated from the recombinant strain SR111-cbmA-OX1-cftC. The chemical structures of 1 and 2 were determined to be the biosynthetic inennediate of ikarugamycin and a new 5/6 dicyclic PoTeM, respectively, by analysis of nuclear magnetic resonance spectroscopy data and high resolution mass spectrometry (HRMS). The antibacterial activity of compounds 1 and 2 was tested by filter paper disc diffusion assay. The results showed that they were inactive at 20 mu g/disc. The cytotoxicity of compounds 1 and 2 was evaluated by methyl thiazolyl tetrazolium (MIT) colorimetric method. Compound 1 showed potent antiproliferative activity against human liver (HepG-2) and breast cancer cell lines (MCF-7) with half maximal inhibitory concentration (IC50) values of 3.34 and 2.72 mu mol/L, respectively, while compound 2 showed no cytotoxicity for the tested cell lines.

Automated summary

The artificial hybrid polycyclic tetramate macrolactam (PoTeM) gene cluster was constructed using combinatory biosynthesis approach, and two PoTeMs were successfully isolated. The chemical structures of the compounds were determined and their antibacterial and cytotoxic activities were tested.