Genome Mining of Amino Group Carrier Protein-Mediated Machinery: Discovery and Biosynthetic Characterization of a Natural Product with Unique Hydrazone Unit

We recently revealed that a Streptomyces strain possesses the gene encoding amino group carrier protein (AmCP). AmCP is involved in the biosynthesis of a previously unidentified nonproteinogenic amino acid, (2S,6R)-diamino-(5R,7)-dihydroxy-heptanoic acid (DADH), which is a core compound for the synthesis of the dipeptide-containing novel natural product vazabitide A. We used polymerase chain reaction (PCR) screening to investigate the diversity of the biosynthetic machinery that uses AmCP; the results revealed that genes encoding AmCP are widely distributed among actinomycetes. The heterologous expression of the AmCP-containing gene cluster from Streptomyces sp. SoC090715LN-17 led to the discovery of s56-p1, a novel natural product. The structure of s56-p1 was determined by spectroscopic analysis; the results revealed that s56-p1 has a putative DADH-derived molecule as the core and also possesses a unique hydrazone unit that is rarely observed in natural products. Our results pave the way for investigations of unexploited AmCP-mediated biosynthesis routes among actinomycetes and of the biosynthetic mechanism of the unique hydrazone unit.