Mannose-Binding Lectin Inhibits the Motility of Pathogenic Salmonella by Affecting the Driving Forces of Motility and the Chemotactic Response

Abstract

Mannose-binding lectin (MBL) is a key pattern recognition molecule in the lectin pathway of the complement system, an important component of innate immunity. MBL functions as an opsonin which enhances the sequential immune process such as phagocytosis. We here report an inhibitory effect of MBL on the motility of pathogenic bacteria, which occurs by affecting the energy source required for motility and the signaling pathway of chemotaxis. When Salmonella cells were treated with a physiological concentration of MBL, their motile fraction and free-swimming speed decreased. Rotation assays of a single flagellum showed that the flagellar rotation rate was significantly reduced by the addition of MBL. Measurements of the intracellular pH and membrane potential revealed that MBL affected a driving force for the Salmonella flagellum, the electrochemical potential difference of protons. We also found that MBL treatment increased the reversal frequency of Salmonella flagellar rotation, which interfered with the relative positive chemotaxis toward an attractive substrate. We thus propose that the motility inhibition effect of MBL may be secondarily involved in the attack against pathogens, potentially facilitating the primary role of MBL in the complement system.

BanLec-eGFP Chimera as a Tool for Evaluation of Lectin Binding to High-Mannose Glycans on Microorganisms

“…Different serovars are differentiated by the structures of their flagellum, carbohydrates, and lipopolysaccharides (LPS) [ 44 , 45 ]. Certain strains of Salmonella are known to contain mannose-rich LPS, and the binding of Mannose-binding lectin (MBL) to this LPS has been investigated [ 46 , 47 , 48 ]. Studies on the effect of MBL binding to S. enterica serovar Typhimurium have revealed the bactericidal properties of MBL [ 39 , 40 ].…”

“…Studies on the effect of MBL binding to S. enterica serovar Typhimurium have revealed the bactericidal properties of MBL [ 39 , 40 ]. The inhibitory effect of MBL on the motility of Salmonella occurs by affecting the energy source required for motility and the signaling pathway of chemotaxis [ 48 ].…”

Collectins: Innate Immune Pattern Recognition Molecules

“…MBL enhances uptake and intracellular killing of Salmonella by neutrophils and monocytes , but this may also involve interaction with fibronectin (Ghiran et al 2000). Recently, MBL has also been shown to have a direct inhibitory effect on flagellar activity in pathogenic Salmonella bacteria, impairing their motility (Xu et al 2016). MBL can also increase uptake of mycobacteria by macrophages (Polotsky et al 1997) and N. meningitidis by neutrophils, monocytes and macrophages (Jack et al 2001), but this uptake by neutrophils may not result in intracellular killing (Drogari-Apiranthitou et al 1997).…”

Knock, knock-let the bacteria in: enzymatic potential of plant associated bacteria

“…In addition, lectins are able to stop the flagella mechanisms, preventing the bacterial movement (Xu et al, 2016). In Azospirillum brasilense, it was demonstrated that the presence of plant lectins with specificity for N-acetyl-β-D-glucosamine oligomers decelerate the bacteria speed and induce granular colonies as a consequence of the interactions between agglutinins and lectin-binding polymers from bacterial cell wall (Schelud'ko et al, 2009).…”