Genetic modifications boost chrexanthomycin yield and neuroprotective potential

Chrexanthomycins, a unique class of pentangular polyphenols (PPs) conjugated with glucuronic acid, have demonstrated remarkable neuroprotective properties both in vitro and in vivo. However, their low yield has restricted their potential applications.

This study aims to clarify the biosynthetic pathway and neuroprotective potency of chrexanthomycins, enhance their large-scale production potential, and discover novel derivatives with improved activities.

Multiple strategies were adopted, such as the heterologous expression of the chr gene cluster, knockout of negative regulators, overexpression of positive regulators, in vitro biochemical reactions, and deletion of tailoring enzymes to clarify the biosynthetic routine of chrexanthomycins. Caenorhabditis elegans was used to evaluate the neuroprotective potential of chrexanthomycins.

Through these approaches, we successfully elucidated the biosynthetic pathway of chrexanthomycins and significantly improved their yields by more than 10-fold in recombinant Streptomyces chrestomyceticus. Additionally, we explored the functions of hydratase ChrN and UDP-glucuronosyltransferase UGT50 in the biosynthesis of chrexanthomycins. Our efforts led to identifying a new derivative, chrexanthomycin G, which exhibited outstanding neuroprotective activities. This novel compound alleviates amyloid-β (Aβ) - induced oxidative stress, inhibits Aβ aggregation, and improves memory in C. elegans through chemotaxis tests.

These findings offer valuable insights into the complex mechanisms of the biosynthesis and biological activities of chrexanthomycins, laying a foundation for their potential application in treating neurodegenerative disorders.