NSF Award
2422727
The many microbial species that colonize plants are in competition with one another on the plant. To win this battle, pathogenic plant microbes employ diverse weapons capable of killing neighboring microbes that belong to other strains without harming microbes of the same strain. The goal of this project is to determine how a potent and common microbe-killing weapon is targeted to some bacteria and not others. If the mechanism of targeting is understood at a basic molecular level, it may become possible to engineer novel antibiotics that kill only certain pathogens without harming “good” bacteria. The project has significant potential to benefit society. Foremost is the security of food to feed people. The mechanisms discovered in this research will apply to food crops and the pathogens that destroy those crops. Discoveries about the evolution of pathogens and how they can be coerced into fighting each other will help agricultural scientists protect food crops of the future. Additionally, the molecules central to this plant-bacteria system are relevant to animals and humans. Understanding how plant pathogens identify and kill each other has the potential for precise control of human pathogens, even those that are rapidly developing resistance to traditional antibiotics. The proposed work will enroll trainees with the NSF-funded STEM Ambassador Program. Each trainee will identify scientifically underserved community groups, design and execute outreach activities, and measure the effectiveness to increase understanding and appreciation of science among nonscientists. <br/><br/>In this project a team of scientists at two sites, in the US and the UK, will work together to unravel mechanisms that Pseudomonas pathogens of plants use to target and kill one another. Bacteria that invade and cause disease in plants make use of molecular killing machines that were derived originally from the tail apparatus of bacteriophages - the viruses of bacteria - and are therefore called tailocins. Tailocins exhibit high specificity in their killing - the tailocins made by a plant pathogen do not attack plant cells or structures, instead kill a subset of other competing bacteria, and somehow avoid killing bacteria of the same strain. Intellectual Merit: The hypothesis to be tested by this project is that killing specificity depends on a particular molecular receptor built into the lipopolysaccharide (LPS) component of the outer membrane. Differences in the carbohydrate composition of the LPS between bacterial strains and species render some strains susceptible to specific tailocins while others are resistant. In this project the LPS differences between bacterial strains that confer resistance and susceptibility to tailocins will be elucidated through a combination of synergistic approaches including plant infection studies, biochemistry, and bioinformatic analysis. In total, the project will discover mechanisms - evolutionary and structural - that suppress a common pathogen in plants and in so doing will address fundamental questions of how to prevent the spread of single strains of bacteria, and how to maintain microbial diversity.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
