Legonaridin, a new member of linaridin RiPP from a Ghanaian Streptomyces isolate†
Linaridins are rare linear ribosomally-synthesized and post-translationally modified peptides (RiPPs) and only two, cypemycin and SGR-1832, in this family have been identified so far. Legonaridin 1 has been discovered as a new member of linaridins through chemical isolation, peptidogenomics, comprehensive 1- and 2-D NMR and advanced Marfey's analyses from the soil bacterium Streptomyces sp. CT34, an isolate collected from Legon, Ghana. Bioinformatics analysis of the gene cluster suggested that the biosynthesis of legonaridin 1 is different from those of cypemycin and SGR-1832. Consistent with bioinformatics and peptidogenomics analyses, 1 has a total of nine post-modifications, 8 dehydrobutyrine residues and a N,N-dimethylated N-terminus with a carboxylic acid at the C-terminus. Legonaridin 1 is structurally different from the two known linaridins comprising a new subfamily. This is the first time that NMR spectroscopy is used to establish the 2-D structure of a linaridin RiPP.