Promoinducin, a Novel Thiopeptide Produced by Streptomyces sp. SF2741

Our continued screening to find tipA promoter-inducing substances resulted in the isolation of promoinducin from a mycelial extract of Streptomyces sp. SF2741. Based on various 1D- and 2D-NMR studies, including field gradient (FG)-COSY, HSQC, FG-HMBC, phase-sensitive ¹³C-decoupled HMBC and NOESY experiments, promoinducin's structure was established to be a thiopeptide composed of threonine, some unusual amino acids masked at their carboxyl groups by thiazole or methyloxazole rings, sulfomycinamate and five dehydroalanine residues. Promoinducin induced the tipA promoter at 40 ng/ml, and also exhibited strong antibacterial activity against some Gram-positive bacteria.