A broadly distributed toxin family mediates contact-dependent antagonism between gram-positive bacteria

John C. Whitney, S. Brook Peterson, Jungyun Kim, Manuel Pazos, Adrian J. Verster, Matthew C. Radey, Hemantha D. Kulasekara, Mary Q. Ching, Nathan P. Bullen, Diane Bryant, Young Ah Goo, Michael G. Surette, Elhanan Borenstein, Waldemar Vollmer, Joseph D. Mougous*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


The Firmicutes are a phylum of bacteria that dominate numerous polymicrobial habitats of importance to human health and industry. Although these communities are often densely colonized, a broadly distributed contact-dependent mechanism of interbacterial antagonism utilized by Firmicutes has not been elucidated. Here we show that proteins belonging to the LXG polymorphic toxin family present in Streptococcus intermedius mediate cell contactand Esx secretion pathway-dependent growth inhibition of diverse Firmicute species. The structure of one such toxin revealed a previously unobserved protein fold that we demonstrate directs the degradation of a uniquely bacterial molecule required for cell wall biosynthesis, lipid II. Consistent with our functional data linking LXG toxins to interbacterial interactions in S. intermedius, we show that LXG genes are prevalent in the human gut microbiome, a polymicrobial community dominated by Firmicutes. We speculate that interbacterial antagonism mediated by LXG toxins plays a critical role in shaping Firmicute-rich bacterial communities.

Original languageEnglish (US)
Article numbere26938
StatePublished - Jul 11 2017

ASJC Scopus subject areas

  • Neuroscience(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)

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