A cyclo-l-Trp-l-Trp tailoring P450 with novel
function from <i>Streptomyces purpureus</i> was identified
by heterologous expression in <i>S. coelicolor</i> 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
