[Characterization of pcr2 gene of Pseudomonas aeruginosa]

Type III secretion system (TTSS) is an important virulence factor encoding by pseudomonas aeruginosa. About 40 genes are involved and they function as structure proteins, chaperons, regulators, and effectors proteins, respectively. Although some genes have been studied previously, functions of many genes remained unknown. Pcr2 gene is the third gene of popN operon that is one of the five operons of the TTSS gene clusters. Its functions were investigated in this study. First, by characterization of the phenotypes of pcr(2-) mutant, we found that the abilities of secreting or translocating effectors proteins were significantly damaged in the absence of Pcr2 protein, suggesting that Pcr2 protein involved in both the secretion and translocation processes of TSS. Second, evidences were provided that no PopN protein was detectable in supernatant of pcr(2-) mutant culture. Combined with the data from the bacterial two-hybrid system, we can conclude that Pcr2 protein might function as part of a chaperone complex for the PopN protein. Third, Pcr2 protein was found secreted in a TTSS-dependent manner, suggesting that secreted Pcr2 may play a role in the TTSS needle biogenesis.