Bacterial Warfare: UCSB researchers demonstrate how gram-negative bacteria deliver toxins to kill neighboring bacteria

Aug 26, 2015

It’s bacteria against bacteria, and one of them is going down. Researchers led by MDCB professor Chris Hayes have demonstrated how certain microbes exploit proteins in nearby bacteria to deliver toxins and kill them. The mechanisms behind this bacterial warfare, the researchers suggest, could be harnessed to target pathogenic bacteria. Their findings appear in the Proceedings of the National Academy of Sciences.

Lead authors Julia L.E. Willett and Grant C. Gucinski have detailed how gram-negative bacteria use contact-dependent growth inhibition (CDI) systems to infiltrate and deliver protein toxins into neighboring cells. By studying the bacteria Escherichia coli (E. coli), they were able to document how CDI “translocation domains” can use multiple pathways to transfer those toxins into a cell. By understanding that mechanism it could be possible to use it as a model for pinpoint targeting of bacteria. CDI was first described by MCDB professor David Low in 2005. Low, a co-author of the current PNAS paper, reported how a bacterial cell would touch a neighboring cell — one that was competing for resources in the environment — and inject it with a toxin. The current research builds on Low’s work by identifying the multiple ways CDI toxins exploit target cells. The key was in understanding the genetics of those targeted bacteria.

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