Mechanism of Adherence of Streptococcus mutans to Smooth Surfaces II. Nature of the Binding Site and the Adsorption of Dextran-Levan Synthetase Enzymes on the Cell-Wall Surface of the Streptococcus

Abstract

The mechanism of adsorption of the Streptococcus mutans enzymes responsible for the synthesis of insoluble dextran-levan to the S. mutans cell-wall binding sites has been studied. Certain characteristics of these binding sites are presented. The adsorption of these enzymes to the cell surface occurred rapidly without the addition of a source of energy and over a pH range of 3 to 11. The adsorption was inhibited by soluble dextran, probably due to the strong affinity of the polymer to the enzyme. All other polymers and sugars studied showed little or no inhibition. The adsorption was also inhibited by antibody globulin to the a-d immunologically specific group antigen surface polysaccharide of S. mutans and by anti-dextran globulin. The inhibition by anti- a-d globulin is considered to be due to a restriction of access of enzyme to the binding site of the enzyme which may be located in close proximity to the group antigen. On the other hand, anti-dextran globulin appeared to directly inhibit the adsorption by covering the binding site. Dextranase destroyed the binding site and released glucose from the S. mutans cells. These data indicate that S. mutans grown in media containing glucose possesses a small amount of dextran on the cell surface, and that this dextran is, or is a part of, the binding site for enzymes which synthesize the insoluble dextran-levan polymer. Trypsin inhibited the synthesis of insoluble polysaccharide and the adherence of cells. It is not clear in this case that destruction of the binding sites occurred. These data present a partial explanation of the processes which may be concerned in the formation of dental plaque on the smooth surfaces of teeth.

Serotype‐Dependent Inhibition of Glucan Synthesis and Cell Adherence of Streptococcus mutans by Antibody against Glucosyltransferase of Serotype e S. mutans

“…It is of interest that antibody directed against extracellular GTase significantly inhibited the cell-associated GTase activity which resulted in the marked reduction in adherence to a glass surface of viable S. mutans cells ( Table 2). It has been found that a portion of the extracellular GTase of S. mutans will bind to the surface of S. mutans cells (18,20,25,28,29), and therefore significant inhibition of GTase activity and cell adherence can be expected.…”

“…It has been shown by in vivo (39) and in vitro (13,16,(28)(29)(30)33) studies that the ability of Streptococcus mutans cells to adhere to smooth surfaces is mediated by glucan synthesis from sucrose by glucosyltransferase (GTase). The GTase of S. mutans is produced extracellularly and is also present in a cell-associated form.…”

PCR detection of Scardovia wiggsiae in combination with Streptococcus mutans for early childhood caries‐risk prediction

“…Early colonisation with mutans streptococci is associated with the prevalence of ECC in preschool children (5). Multiple virulence factors of Streptococcus mutans, including its ability to produce and survive in acidic environments (6) and to express a water-insoluble membrane-bound polysaccharide providing bacterial attachment (7), support the theory that it is the primary microbial cause of dental caries (8). Other factors affecting the level of S. mutans, including salivary pH and flow, and diet, also increase the risk of caries (9).…”

Chemical Composition of Streptococcus mutans Cell Walls and Their Susceptibility to Flavobacterium L‐11 Enzyme

“…On the other hand, it was found that serotype e MT703 cell walls were not susceptible to the L-11 enzyme, whereas B2 cell walls of the same serotype e were significantly lyzed by the enzyme. This indicates that the presence of other cell-surface components such as fuzzy coat (4, 37), glucan-binding proteins (24,32,46), and exogenous cell-bound glucans (15,25,31,35,44,46) may also affect the susceptibility of S. mutans cell walls to the lytic enzyme. However, conclusion about the cause(s) of the insensitivity of MT703 (e) , AHT (g) , and 6715 (g) cell walls to the enzyme should await further examination.…”