A Unique Pathway for the 3‑Aminobutyrate Starter Unit from l‑Glutamate through β‑Glutamate during Biosynthesis of the 24-Membered Macrolactam Antibiotic, Incednine

Abstract

Incednine is a 24-membered macrolactam antibiotic produced by <i>Streptomyces</i> sp. ML694-90F3. A previous study demonstrated that its unique nitrogen-containing starter unit was derived from l-glutamate. To elucidate the missing link between l-glutamate and the starter unit, deuterium labeled amino acid feeding experiments were conducted. These experiments revealed that 3-[3-²H]aminobutyrate and β-[2,2,4,4-²H₄]glutamate were incorporated into the starter moiety. The results indicate that a novel decarboxylation of β-glutamate to give 3-aminobutyrate is involved in incednine biosynthesis