4‑Hydroxy Pyridones from Heterologous Expression and Cultivation of the Native Host

4-Hydroxy pyridones are a class of fungi-derived polyketide–nonribosomal
peptide products featuring a core of 4-hydroxy-2-pyridone which have
a wide range of biological activities. Genome mining of in-house strains
using polyketide synthase–nonribosomal peptide synthase as
a query identified an endophyte Tolypocladium sp.
49Y, which possesses a potential 4-hydroxy pyridone biosynthetic gene
cluster. Heterologous expression in Aspergillus oryzae NSAR1 revealed that this gene cluster is functional and able to
produce a rare type of 4-hydroxy pyridones called tolypyridones (compounds 3 and 4). Tolypocladium sp.
49Y was grown in a variety of media which led to the isolation of
six 4-hydroxy pyridones (5–10) and
one pyrrolidone (11) from a rice culture, and compounds 3 and 9 showed antifungal activity. These latter
compounds are different from those obtained by heterologous expression.
This study shows that both heterologous expression and cultivation
of the native host are complementary approaches to discover new natural
products.