Coupling of Guanine with cyclo-L-Trp-L-Trp Mediated by a Cytochrome P450 Homologue from Streptomyces purpureus

A cyclo-L-Trp-L-Trp tailoring P450 with novel function from Streptomyces purpureus was identified by heterologous expression in S. coelicolor and in vitro assays the recombinant protein. Structural elucidation revealed that this enzyme catalyzes the transfer of a guanine moiety to the indole ring of the cyclodipeptide via a C-N bond. Adduct products of CDP and guanine are unprecedented in nature, and CDP modification by coupling with guanine has not been reported prior to this study.