Localization of a Type III secretion chaperone SpcU within Pseudomonas Bacterial cells

Pseudomonas aeruginosa is an opportunistic bacterial pathogen which is primarily known for causing severe respiratory infection in patients with cystic fibrosis. It is a Gram-negative rod that has several different virulence factors. One virulence factor is the exotoxin ExoU which is secreted into host cells by a specific secretion system referred to as the Type III secretion system (TTSS). Type III secretion is a topic of interest because it is the means by which many bacterial pathogens deliver toxins to cells inside their infected host. Many toxins require a chaperone for secretion by the TTSS, but the role of the toxin is not known. To learn more about the role of Type III chaperones, I have been examining the role of the P. aeruginosa chaperone SpcU in the secretion of ExoU. I have constructed a HA-tagged version of SpcU so that we can monitor the localization of SpcU in cells. We have examined whether SpcU is located in the soluble cytoplasmic fraction or is associated with membranes in the bacterial cells by Western immunoblots. From the Western blots done it has been found that a high concentration of SpcU exists in the soluble cytoplasmic fraction of the cells. Through Western blots and Immunoblotting procedures there is evidence of the chaperones existence in the soluble cytoplasmic fraction. Now the lab is trying to find a way to shut down the SpcU chaperone to discontinue the Pseudomonas toxin ExoU from being delivered to a host cell