Discovery of Acyl-Surugamide A2 from Marine Streptomyces albidoflavus RKJM-0023-A New Cyclic Nonribosomal Peptide Containing an N-ε-acetyl-L-lysine Residue.

We report the discovery of a novel cyclic nonribosomal peptide (NRP), acyl-surugamide A2, from a marine-derived Streptomyces albidoflavus RKJM-0023 (CP133227). The structure of acyl-surugamide A2 was elucidated using a combination of NMR spectroscopy, MS2 fragmentation analysis, and comparative analysis of the sur biosynthetic gene cluster. Acyl-surugamide A2 contains all eight core amino acids of surugamide A, with a modified N-ε-acetyl-L-lysine residue. Our study highlights the potential of marine Streptomyces strains to produce novel natural products with potential therapeutic applications. The structure of cyclic peptides can be solved using MS2 spectra and analysis of their biosynthetic gene clusters.