Diphtheria toxin (DT), produced by Corynebacterium diphtheria, is the causative agent of diphtheria and one of the most potent protein toxins known; however, it has an unclear evolutionary history. Here, we report the discovery of a DT-like gene family in several bacterial lineages outside of Corynebacterium, including Austwickia and Streptomyces. These DT-like genes form sister lineages in the DT phylogeny and conserve key DT features including catalytic and translocation motifs, but possess divergent receptor-binding domains. DT-like genes are not associated with corynephage, but have undergone lateral transfer through a separate mechanism. The discovery of the first non-Corynebacterium homologs of DT sheds light on its evolutionary origin and highlights novelties that may have resulted in the emergence of DT targeting humans.
CITATION STYLE
Mansfield, M. J., Sugiman-Marangos, S. N., Melnyk, R. A., & Doxey, A. C. (2018). Identification of a diphtheria toxin-like gene family beyond the Corynebacterium genus. FEBS Letters, 592(16), 2693–2705. https://doi.org/10.1002/1873-3468.13208
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