Biosynthesis of 4-Formyl-4-imidazoIine-2-on, the Heterocyclic Base of Nikkomycin X

The nucleoside-peptide antibiotic nikkomycin X contains the unusual heterocyclic base 4-formyl-4-imidazoline-2-on. Investigations on the biosynthesis of this base were accomplished in a resting cell system which was optimized in respect to nikkomycin production. Incorporation experiments with [2-l4C]adenine, [8 14C]adenine, [2-14C]glycine, [2-14C]uracil, [U 14C]histidine, and [2-14C]histidine revealed that only [2-14C]adenine, [U 14C]and [2-14C]histidine were specifically incorporated into nikkomycin X. An incorporation experim ent with [2-13C]adenine resulted in a 31-fold enrichment of the carbon atom 2 of 4-formyl-4-imidazoline2-on. These results show that the heterocyclic base of nikkomycin X is a product o f the histidine biosynthetic pathway.