Critical intermediates reveal new biosynthetic events in the enigmatic colibactin pathway

Abstract

Colibactin is a potent genotoxin that induces DNA double-strand breaks; it is produced by Escherichia coli strains harboring a pks+ island. It has been ten years since the discovery of this pks+ island (the colibactin biosynthetic gene cluster). The pathogenicity and the underlying mechanisms of these pks+ strains are in the process of being elucidated. However, the precise chemical structure of colibactin remains elusive, which severely hampers attempts to acquire an in-depth understanding of this compound. Here, using transformation-associated recombination (TAR) cloning to perform heterologous expression, I 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 novel 1H-pyrrolo[3,4-c]pyridine-3,6(2H,5H)-dione- and thiazole-containing 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.

Date of Award	2016
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology