Critical Intermediates Reveal New Biosynthetic Events in the Enigmatic Colibactin Pathway

• Published in: Chembiochem : a European journal of chemical biology 2015-08, Vol.16 (12), p.1715-1719
• Main Authors: Li, Zhong-Rui, Li, Yongxin, Lai, Jennifer Y. H., Tang, Jianqiang, Wang, Bin, Lu, Liang, Zhu, Guoqiang, Wu, Xiyang, Xu, Ying, Qian, Pei-Yuan
• Format: Article
• Language: English
• Subjects: Cloning, Molecular; colibactin; DNA repair; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli - physiology; Gene Expression Regulation; heterologous expression; Peptides - chemistry; Peptides - metabolism; Polyketides - chemistry; Polyketides - metabolism; precolibactin; prodrug mechanism
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.201500239

Colibactin is a potent genotoxin that induces DNA double‐strand breaks; it is produced by Escherichia coli strains harboring a pks+ island. However, the structure of this compound remains elusive. Here, using transformation‐associated recombination (TAR) cloning to perform heterologous expression, we took advantage of the significantly increased yield of colibactin pathway‐related compounds to determine and isolate a series of vital (pre)colibactin intermediates. The chemical structures of compounds 8, 10 and 11 were identified by NMR and MSn analyses. The new 1H‐pyrrolo[3,4‐c]pyridine‐3,6(2H,5H)‐dione‐ and thiazole‐containing compound 10 provides new insights regarding the biosynthetic pathway to (pre)colibactin and establishes foundations for future investigation of the intriguing (pre)colibactin structures and its modes of action. A vital precolibactin intermediate was isolated and identified as a new 1H‐pyrrolo[3,4‐c]pyridine‐3,6(2H,5H)‐dione‐ and thiazole‐containing compound. Based on its structure together with gene‐knockout experiments, we mapped its logical biosynthetic pathway. Our results lay a foundation for further work to determine the enzymatic events in this mysterious pathway.