A putative enolpyruvyl transferase gene involved in nikkomycin biosynthesis

The nikO gene encoding a putative enolpyruvyl transferase has been identifi ed within the Streptomyces tendae Tu901/8c nikkomycin gene cluster. nikO en codes a deduced protein of 471 aminoacid residues which exhibits significan t sequence similarity to UDP-N-acetyl-glucosamine enolpyruvyl transferase a nd 5-enol-pyruvylshikimate 3-phosphate synthase from various origin. The ni kO gene was inactivated by inserting a kanamycin resistance cassette; the m utant did not produce biologically active nikkomycins I, J, X, and Z nor th e nucleoside moieties, nikkomycins C-x and C-z, but accumulated the novel c omponent RT 2.0. RT 2.0 has been isolated from culture filtrate and its str ucture was determined by using mass spectrometry and NMR analyses as ribofu ranosyl-4-formyl-4-imidazolone which represents a novel nucleoside. The put ative activity of the nikO gene product in nikkomycin biosynthesis will be discussed.