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Investigating molecular mechanisms of calcium signaling in bacterial pathogen Pseudomonas aeruginosa

Rogers, Rendi

Pseudomonas aeruginosa is a human pathogen that, along with causing other various types of infections, is the leading cause of death in patients with cystic fibrosis (CF). Research in Patrauchan's lab has shown that increased levels of calcium (Ca2+) induce the production of several virulence factors in P. aeruginosa, including extracellular proteases, alginate, pyocyanin, formation of biofilm, and antibiotic resistance. Currently, the mechanisms of Ca2+ signaling in prokaryotes have been inadequately studied and are not clear. In order to study the molecular mechanisms regulating Ca2+-induced virulence in P. aeruginosa, the Patrauchan lab had predicted several putative Ca2+-binding proteins. The group identified the only calmodulin-like protein encoded in the P. aeruginosa genome, EfhP. This protein contains two canonical Ca2+-binding EF-hand domains. EfhP was also shown to be involved in mediating Ca2+-regulated virulence and resistance in the pathogen. The principal goal of this research has been to elucidate the role that EfhP plays in regulating Ca2+-induced virulence of P. aeruginosa. To achieve this goal, I aimed to: (1) purify EfhP and measure its Ca2+-binding properties, (2) identify specific amino acids binding Ca2+ in EfhP, and (3) study the environmental factors affecting transcriptional regulation of the encoding gene, efhP. This knowledge is imperative for characterizing the functional role of EfhP. Considering the importance of Ca2+ signaling in a host, its understanding would provide an insight into the regulatory networks orchestrating virulence and interactions with a host in P. aeruginosa. The latter is essential for future development or novel therapeutic approaches to prevent or control Pseudomonas infections.