The azinomycins are potent antitumor agents produced by the soil bacterium Streptomyces sahachiroi and contain a novel aziridino[1,2-a]pyrrolidine core; its synthesis involves at least 14 steps. This study reports the first reconstitution of N-acetylglutamine semialdehyde formation by two enzymes encoded in the azinomycin biosynthetic gene cluster. The reaction proceeds through the formation of an acylphosphate and establishes N-acetyl-glutamyl 5-phosphate and N-acetylglutamine semialdehyde as intermediates in the complex biosynthesis of the aziridino[1,2-a]pyrrolidine moiety.

The azinomycins are a family of potent antitumor agents with the ability to form interstrand cross-links with DNA. This study reports on the unusual biosynthetic formation of the 5-methyl naphthoate moiety, which is essential for effective DNA association. While sequence analysis predicts that the polyketide synthase (AziB) catalyzes the formation of this naphthoate, 2-methylbenzoic acid, a truncated single-ring product, is formed instead. We demonstrate that the thioesterase (AziG) acts as a chain elongation and cyclization (CEC) domain and is required for the additional two rounds of chain extension to form the expected product.