Liang Deng#, Zhihu Zhao#, Lin Liu, Zhiyu Zhong, Wenxinyu Xie, Fan Zhou, Wei Xu, Yubo Zhang, Zixin Deng, and Yuhui Sun*
Proceedings of the National Academy of Sciences of the United States of America 2023, 120:e2222045120
Epub Date: 6 March 2023
The soil-dwelling filamentous bacteria, Streptomyces, is widely known for its ability to produce numerous bioactive natural products. Despite many efforts toward their overproduction and reconstitution, our limited understanding of the relationship between the host's chromosome three dimension (3D) structure and the yield of the natural products escaped notice. Here, we report the 3D chromosome organization and its dynamics of the model strain, Streptomyces coelicolor, during the different growth phases. The chromosome undergoes a dramatic global structural change from primary to secondary metabolism, while some biosynthetic gene clusters (BGCs) form special local structures when highly expressed. Strikingly, transcription levels of endogenous genes are found to be highly correlated to the local chromosomal interaction frequency as defined by the value of the frequently interacting regions (FIREs). Following the criterion, an exogenous single reporter gene and even complex BGC can achieve a higher expression after being integrated into the chosen loci, which may represent a unique strategy to activate or enhance the production of natural products based on the local chromosomal 3D organization.
Guifa Zhai#, Yan Zhu#, Guo Sun, Fan Zhou, Yangning Sun, Zhou Hong, Chuan Dong, Peter F. Leadlay, Kui Hong, Zixin Deng, Fuling Zhou, and Yuhui Sun*
Nature Communications 2023, 14:612
Epub Date: 4 February 2023
Modular polyketide synthase (PKS) is an ingenious core machine that catalyzes abundant polyketides in nature. Exploring interactions among modules in PKS is very important for understanding the overall biosynthetic process and for engineering PKS assembly-lines. Here, we show that intermodular recognition between the enoylreductase domain ER1/2 inside module 1/2 and the ketosynthase domain KS3 inside module 3 is required for the cross-module enoylreduction in azalomycin F (AZL) biosynthesis. We also show that KS4 of module 4 acts as a gatekeeper facilitating cross-module enoylreduction. Additionally, evidence is provided that module 3 and module 6 in the AZL PKS are evolutionarily homologous, which makes evolution-oriented PKS engineering possible. These results reveal intermodular recognition, furthering understanding of the mechanism of the PKS assembly-line, thus providing different insights into PKS engineering. This also reveals that gene duplication/conversion and subsequent combinations may be a neofunctionalization process in modular PKS assembly-lines, hence providing a different case for supporting the investigation of modular PKS evolution.