Summary Quinocarcin and SF-1739, potent antitumor antibiotics, share a common tetracyclic tetrahydroisoquinoline (THIQ)-pyrrolidine core scaffold. Herein, we describe the identification of their biosynthetic gene clusters and biochemical analysis of Qcn18/Cya18 generating the previously unidentified extender unit dehydroarginine, which is a component of the pyrrolidine ring. ATP-inorganic pyrophosphate exchange experiments with five nonribosomal peptide synthetases (NRPSs) enabled us to identify their substrates. On the basis of these data, we propose that a biosynthetic pathway comprising a three-component NRPS/MbtH family protein complex, Qcn16/17/19, plays a key role in the construction of tetracyclic THIQ-pyrrolidine core scaffold involving sequential Pictet-Spengler and intramolecular Mannich reactions. Furthermore, data derived from gene inactivation experiments led us to propose late-modification steps of quinocarcin. © 2013 Elsevier Ltd.
Hiratsuka, T., Koketsu, K., Minami, A., Kaneko, S., Yamazaki, C., Watanabe, K., … Oikawa, H. (2013). Core assembly mechanism of quinocarcin/SF-1739: Bimodular complex nonribosomal peptide synthetases for sequential mannich-type reactions. Chemistry and Biology, 20(12), 1523–1535. https://doi.org/10.1016/j.chembiol.2013.10.011