Influence of Heterologously Expressed azurin from Pseudomonas aeruginosa on the Adhesion and Invasion of Pathogenic Bacteria to the Caco-2 Cell Line

Abstract

This study proposed to investigate the effect of azurin on the major stages of pathogenesis (adhesion and invasion) of intestinal bacterial pathogens (Salmonellaspp. andEscherichia coli) and epithelial pathogens (Staphylococcus aureusandPseudomonas aeruginosa) on the human colorectal adenocarcinoma (Caco-2) cell line. Azurin protein was produced by cloning theazuringene into pET21a and heterologous expression inE. coliBL21. The protein was purified using affinity chromatography and confirmed by Western blotting. The purified protein was evaluated by three experiments of adhesion and invasion assays, including exclusion, competition, and replacement. Azurin was observed to significantly inhibit the attachment and invasion ofS. aureus,Salmonellaspp., andE. coli, while no such inhibitory effects were observed onP. aeruginosa. In fact, the protein increased the adhesion ofP. aeruginosato the cell. In conclusion, our study proposes that azurin is a potential prophylactic or preventive helper candidate to inhibit the attachment and invasion of pathogenic bacteria to host cells and reduce the progression of the infection process. Our study also reveals the involvement of azurin in bacteria-host cell interactions, providing novel and important insights toward the elucidation of its biological function in this field. Thus, this study provides new opportunities to use azurin as an adjunct therapy against critical stages of infection by a wide range of pathogenic bacteria.