Carlson Erik S, Haslecker Raphael, Lecchi Chiara, Ramos Miguel Aguilar, Vennelakanti Vyshnavi, Honaker Linda, Stornetta Alessia, Millán Estela S, Johnson Bruce A, Kulik Heather J, Balbo Silvia, Villalta Peter W, D'Souza Victoria, Balskus Emily P
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
bioRxiv. 2025 May 27:2025.05.26.655968. doi: 10.1101/2025.05.26.655968.
Accumulating evidence has connected the chemically unstable, DNA-damaging gut bacterial natural product colibactin to colorectal cancer, including the identification of mutational signatures that are thought to arise from colibactin-DNA interstrand crosslinks (ICLs). However, we currently lack direct information regarding the structure of this lesion. Here, we combine mass spectrometry and nuclear magnetic resonance spectroscopy to elucidate the specificity and structure of the colibactin-DNA ICL. We find that colibactin alkylates within the minor groove of AT-rich DNA, explaining the origins of mutational signatures. Unexpectedly, we discover that the chemically unstable central motif of colibactin mediates the sequence specificity of crosslinking. By directly elucidating colibactin's interactions with DNA, this work enhances our understanding of the structure and genotoxic mechanisms of this unique cancer-linked gut bacterial natural product.
越来越多的证据将化学性质不稳定、具有DNA损伤作用的肠道细菌天然产物大肠杆菌素与结直肠癌联系起来，这其中包括对被认为由大肠杆菌素-DNA链间交联（ICL）产生的突变特征的识别。然而，我们目前缺乏关于这种损伤结构的直接信息。在此，我们结合质谱和核磁共振光谱来阐明大肠杆菌素-DNA ICL的特异性和结构。我们发现大肠杆菌素在富含AT的DNA小沟内发生烷基化，这解释了突变特征的起源。出乎意料的是，我们发现大肠杆菌素化学性质不稳定的中心基序介导了交联的序列特异性。通过直接阐明大肠杆菌素与DNA的相互作用，这项工作增进了我们对这种与癌症相关的独特肠道细菌天然产物的结构和遗传毒性机制的理解。
