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bioRxiv · 10.1101/567248

The reactivity of an unusual amidase may explain colibactin’s DNA cross-linking activity

Jiang, Y.·Stornetta, A.·Villalta, P. W.·Wilson, M. R.·Boudreau, P. D.·Zha, L.·Balbo, S.·Balskus, E. P.
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Abstract

Certain commensal and pathogenic bacteria produce colibactin, a small molecule genotoxin that causes interstrand cross-links in host cell DNA. Though colibactin has been found to alkylate DNA, the molecular basis for cross-link formation is unclear. Here, we report that the colibactin biosynthetic enzyme ClbL is an amide bond-forming enzyme that links aminoketone and {beta}-keto thioester substrates in vitro and in vivo. The substrate specificity of ClbL strongly supports a role for this enzyme in terminating the colibactin NRPS-PKS assembly line. This transformation would incorporate two electrophilic cyclopropane warheads into the final natural product scaffold. Overall, this work provides a biosynthetic explanation for colibactins DNA crosslinking activity and paves the way for further study of its chemical structure.

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Jiang, Y., Stornetta, A., Villalta, P. W., Wilson, M. R., Boudreau, P. D., Zha, L., Balbo, S., Balskus, E. P.. 2019-03-04. The reactivity of an unusual amidase may explain colibactin’s DNA cross-linking activity. https://doi.org/10.1101/567248

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