Rhamnose Binding Protein as an Anti-Bacterial Agent-Targeting Biofilm of .

More than 80% of infectious bacteria form biofilm, which is a bacterial cell community surrounded by secreted polysaccharides, proteins and glycolipids. Such bacterial superstructure increases resistance to antimicrobials and host defenses. Thus, to control these biofilm-forming pathogenic bacteria requires antimicrobial agents with novel mechanisms or properties. , a Gram-negative opportunistic nosocomial pathogen, is a model strain to study biofilm development and correlation between biofilm formation and infection. In this study, a recombinant hemolymph plasma lectin (rHPL) cloned from Taiwanese was expressed in an system. This rHPL was shown to have the following properties: (1) Binding to PA14 biofilm through a unique molecular interaction with rhamnose-containing moieties on bacteria, leading to reduction of extracellular di-rhamnolipid (a biofilm regulator); (2) decreasing downstream quorum sensing factors, and inhibiting biofilm formation; (3) dispersing the mature biofilm of PA14 to improve the efficacies of antibiotics; (4) reducing PA14 cytotoxicity to human lung epithelial cells in vitro and (5) inhibiting PA14 infection of zebrafish embryos in vivo. Taken together, rHPL serves as an anti-biofilm agent with a novel mechanism of recognizing rhamnose moieties in lipopolysaccharides, di-rhamnolipid and structural polysaccharides (Psl) in biofilms. Thus rHPL links glycan-recognition to novel anti-biofilm strategies against pathogenic bacteria.