Biosynthesis of Cyclochlorotine: Identification of the Genes Involved in Oxidative Transformations and Intramolecular ,-Transacylation.

Mycotoxin cyclochlorotine () and structurally related astins are cyclic pentapeptides containing unique nonproteinogenic amino acids, such as β-phenylalanine, l--threonine, and 3,4-dichloroproline. Herein, we report the biosynthetic pathway for , which involves intriguing tailoring processes mediated by DUF3328 proteins, including stereo- and regiospecific chlorination and hydroxylation and intramolecular ,-transacylation. Our findings demonstrate that DUF3328 proteins, which are known to be involved in oxidative cyclization of fungal ribosomal peptides, have much higher functional diversity than previously expected.