Heterologous expression of a cdps-p450 locus from Streptomyces sp. NRRL S-1521
led to
the identification of guanitrypmycin D1, a new guaninylated diketopiperazine.
The cytochrome P450 GutD1521 catalyzed the regiospecific
transfer of guanine to C-2 of the indole ring of cyclo-(l-Trp-l-Tyr) via a C–C linkage and represents
a new chemical transformation within this enzyme class. Furthermore,
GutD1521 efficiently accepts several other tryptophan-containing
cyclodipeptides or derivatives for regiospecific coupling with guanine,
thus generating different guanitrypmycin analogs