Flavacol and Its Novel Derivative 3--Hydroxy Flavacol from sp. Pv 4-95 after the Expression of Heterologous AdpA.

Actinomycetes are one of the main producers of biologically active compounds. However, their capabilities have not been fully evaluated due to the presence of many unexpressed silent clusters; moreover, actinomycetes can probably produce new or previously discovered natural products under certain conditions. Overexpressing the gene into streptomycetes strains can unlock silent biosynthetic gene clusters. Herein, we showed that by applying this approach to sp. Pv 4-95 isolated from rhizosphere soil, two new mass peaks were identified. NMR structure analysis identified these compounds as flavacol and a new 3--hydroxy flavacol derivative. We suggest that the presence of heterologous AdpA has no direct effect on the synthesis of flavacol and its derivatives in the Pv 4-95 strain. However, AdpA affects the synthesis of precursors by increasing their quantity, which then condenses into the resulting compounds.