Role of a FAD-dependent monooxygenase in diazo group functionalisation of kinamycin in Streptomyces ambofaciens

Abstract

Kinamycin biosynthesis is a complex process which has been extensively studied over the years, yet specific enzymatic steps continue to be unveiled. A diazo group present in the molecule is responsible for the promising antitumoral activity of kinamycins but its specific installation in Streptomyces ambofaciens is not fully understood. In this study, we explore the diazo functionalization of kinamycin in this strain. A new FAD-dependent monooxygenase is identified which is essential for kinamcyin biosynthesis. In its absence, stealthin C accumulates instead likely as a pathway shunt-product. Furthermore, as a result of the position of the gene encoding this monooxygenase, named alp2F, we also propose new boundaries of the kinamycin biosynthetic gene cluster resulting in a large cluster spanning over 72kb. This work paves the way for the continued understanding of the biosynthetic steps that are characteristic of diazo-containing natural products, and provides new biocatalysts for molecular engineering and accelerate bioactive compounds production.