Author(s): Ella Bleak
Mentor(s): Talia Karasov, Talia Backman
Institution U of U
Phage-tail-like bacteriocins, also known as tailocins, are virus-like toxins used by bacteria to compete with other bacteria for resources. Tailocins have highly specific killing abilities; they can kill genetically closely related bacteria, but not the producing strain or more distant bacterial relatives, and because of this specificity they are promising alternatives to antibiotics. In 2019, the CDC estimated more than 2.8 million antibiotic-resistant infections occur in the U.S. annually, with more than 35,000 deaths. As antibiotic resistance is becoming more prevalent, alternative therapies are becoming increasingly necessary. To ultimately develop tailocins for clinical treatment, more research is needed to understand the underlying mechanisms of tailocin specificity. The Karasov Lab studies tailocins produced by wild populations of the pathogenic bacterium Pseudomonas syringae, an abundant pathogen that infects the model plant, Arabidopsis thaliana. We found that tailocins are highly conserved in wild populations of P. syringae and frequently used in bacterial competition amongst pathogenic strains. We identified 70 genes in the P. syringae genome which were involved in a bacterial sensitivity to a tailocin. 6 were involved in the biosynthesis of the O-Antigen Polysaccharide (O-PS): an important part of the lipopolysaccharide (LPS) found on gram-negative bacterial membranes which contain long sugar chains. Tailocins bind target cells with high specificity by using their tail fibers to interact with target cell O-PS akin to a lock and key interaction. My current research aims to broadly characterize the LPS of strains of wild P. syringae to identify relationships between LPS composition and sensitivity to tailocin. Additionally, I aim to identify specific sugar monosaccharides that make up the O-PS which the tail fibers bind to. This research will greatly contribute to the understanding of tailocin-LPS interactions to better understand how tailocins identify and kill their targets, and how bacteria evolve resistance to tailocins.