A unique pathway for the 3-aminobutyrate starter unit from L-glutamate through β-glutamate during biosynthesis of the 24-membered macrolactam antibiotic, incednine.

Incednine is a 24-membered macrolactam antibiotic produced by Streptomyces 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.