Characterization of Lactoferrin Interaction with Streptococcus mutans

Abstract

Lactoferrin (LF) is an iron-binding glycoprotein common to exocrine secretions and the specific granules of neutrophils. Each molecule is capable of high-affinity coordinate-binding of two ferric ions with two bicarbonate or carbonic anions. The initial aspect of the present study was directed at determining the nature of anion involvement in LF bactericidal activity. It was found that selective anions were capable of inhibiting the expression of bactericidal activity by LF on S. mutans 10449. The ability to block LF expression was directly related to the capacity of the anion to serve as a coordinate ion in iron-binding by the transferrin molecules. These data support the hypothesis that the LF target site on the bacterial surface is anionic. There has been controversy in the literature regarding LF involvement in hydroxy radical generation. The second phase of these studies indicated that treatment of S. mutans with LF under anaerobic conditions abrogated the bactericidal effect of this molecule. LF-killing could be enhanced by the presence of thiocyanate and inhibited by catalase and lactoperoxidase; however, bovine serum albumin was equally effective as an inhibitor. The apparent requirement for oxygen in LF bactericidal effect on S. mutans is not inconsistent with a hydroxy radical mechanism.

Inhibitory Effect of Bovine Milk Lactoferrin on the Interaction between a Streptococcal Surface Protein Antigen and Human Salivary Agglutinin

“…Lactoferrin is viewed as a potential contributor to dental caries prevention by virtue of its inhibitory effect on the binding of S. mutans to acquired pellicles on the tooth surface and its bactericidal action on S. mutans (18). We have now demonstrated that bovine lactoferrin inhibits the interaction between PAc of S. mutans and salivary agglutinin by binding strongly to salivary agglutinin.…”

“…Casein and lactoperoxidase have been reported to inhibit the adherence of S. mutans to saliva-coated hydroxyapatite (15,16). -Casein reduces the glucosyltransferase activity of S. mutans, which in turn reduces glucan formation (17), and lactoferrin has a bactericidal effect on S. mutans (18). In this study, we examined the effects of bovine milk on the saliva-induced aggregation of S. mutans cells.…”

Saliva-Bacterium Interactions in Oral Microbial Ecology

“…A variety of Gram-positive and Gram-negative bacteria are susceptible to the actions of apolactoferrin (Amold et al, 1980), which requires the direct binding of the protein to the bacterial surface. This action involves an anionic target site for lactofernin on the surface of these microorganisms (Lassiter et al, 1987). In addition to this bacteriocidal activity, apolactoferrin has also been found to inhibit the adhesion of S. sobrinus to HA (Visca et al, 1989).…”

Does Variability in Salivary Protein Concentrations Influence Oral Microbial Ecology and Oral Health?

“…However, some pathogens use siderophores to scavenge iron from lactoferrin (Williams and Carbonetti, 1986), and others have lactoferrin receptors that allow them to use it directly as an iron source (Herrington and Sparling, 1985). Unsaturated lactoferrin has an independent bactericidal effect which may be mediated by the generation of # OH radicals (Lassiter et al, 1987). Lactoferrin recently has been shown to participate in aggregation and adherence (SoukkaeU/., 1993(SoukkaeU/., , 1994.…”

“…Lactoferrin, slgA, and lysozyme all may increase inhibitory effects of peroxidase (Tenovuo et al, 1982;Lenander-Lumikari et al, 1992a), and slgA against bacterial iron-binding proteins may enhance bacteriostatic iron-sequestration by lactoferrin (Ellison et al, 1988). On the other hand, bactericidal actions of lactoferrin can be blocked or enhanced by slgA specific to particular species (Lassiter et al, 1987;Motley and Arnold, 1987). Polycationic anti-membrane effects of lysozyme may be enhanced by peroxidase-generated hypothiocyanite (Pollock et al, 1987), but peroxidase itself may non-specifically block bactericidal effects of lactoferrin (Lassitereta!., 1987).…”