Filamentous haemagglutinin proteins as novel toxins of Pseudomonas aeruginosa

Patients undergoing cardiovascular operations are at significant risk for nosocomial infections. These patients often require long-term mechanical ventilation making them at high risk for ventilator-associated pneumonia (VAP). Pseudomonas aeruginosa is the most common causative agent of VAP among cardiovascular patients, and is an extremely important nosocomial pathogen. Scientific research is needed to better understand the pathogenic mechanisms utilized by P. aeruginosa. The ultimate goal will then be to translate this information into the development of novel therapeutics for controlling P. aeruginosa infections. Severe and invasive P. aeruginosa infections often occur when an individual strain of P. aeruginosa acquires additional virulence factors through horizontal gene transfer. We have identified one such novel virulence factor referred to as Filamentous Haemagglutinin-Like protein B (FhlB). We hypothesize FhlB to act like a molecular spike that injects a toxic, carboxy-tip with predicted GTPase Activating Protein (GAP) function into target cells. This would disrupt host GTPase proteins to then disable or kill target cells. Bacterial mutants of fhlB or simply the toxic carboxy-tip are significantly attenuated in mouse infections models, suggesting that the carboxy-tip of FhlB has a particularly important virulence function. Very little is known about the function of FhlB proteins and their role in the pathogenesis of P. aeruginosa. For this project, Dr. Allen aims to expand on his preliminary findings to identify the toxic mechanism of FhlB1. These studies will also serve as a training opportunity for Dr. Allen to learn several cell biology, protein biology, and biochemical techniques. Understanding how FhlB proteins function as a toxin delivery system is crucial for a comprehensive understanding of the complex mechanisms that encompass P. aeruginosa pathogenicity. FhlB proteins are common among bacterial pathogens, thus findings from this work could be used to investigate how FhlB proteins may function as broad class of virulence factors. This training will provide Dr. Allen with the required training in biochemical and cellular techniques that will be necessary to gain his research independence. Dr. Hausers laboratory provides a unique environment to gain expertise in numerous experimental techniques required in this proposal. Dr. Hauser has an impressive track record of identifying and characterizing the function of several P. aeruginosa