Contributions of Three Glucosyltransferases to Sucrose-dependent Adherence of Streptococcus mutans

Abstract

Streptococcus mutans produces 3 types of glucosyltransferase (GTF), whose cooperative action is considered to be essential for its cellular adherence to the tooth surface. However, the precise mechanisms for synthesizing adhesive glucans and the specific roles of each GTF in cellular adherence to smooth surfaces have not been elucidated. In the present study, seven types of isogenic mutants of S. mutans MT8148 lacking GTFB, GTFC, and/or GTFD activities were constructed by inactivation of the genes encoding GTFB, GTFC, and/or GTFD. Furthermore, recombinant GTFB, GTFC, and GTFD were prepared from Escherichia coli cells harboring recombinant plasmids containing each of the gtf genes. Using these GTF-deficient mutants and rGTFs, we reconstituted sucrose-dependent adherence of S. mutans resting cells and examined the role of each GTF in vitro. The highest level of sucrose-dependent adherence was found at the ratio of 20 rGTFB:1 rGTFC:4 rGTFD in both the resting cells of GTF-deficient mutants and insoluble glucan synthesized by rGTFs. Moreover, when rGTFC and rGTFD were both present at concentrations of 1.5 mU and 6 mU, respectively, the insoluble glucan synthesized from sucrose by the rGTFs showed a high level of adhesiveness to smooth surfaces, even without rGTFB. These results suggest that the presence of all three GTFs at the optimum ratio is necessary for sucrose-dependent adherence of S. mutans, and that GTFC and GTFD may play significant roles in the synthesis of adhesive and insoluble glucan from sucrose.

Evaluation of biofilm formation in the presence of saliva on poly(ethylene glycol)deposited titanium

“…S. mutans MT8148, the laboratory strain, have been found to be capable of producing three major glucosyltransferases. In the presence of sucrose, the glucosyltransferase enzymes produce water-insoluble glucan, which is related to the adhesion and formation of biofilm [47][48][49] . The sucrose-dependent adherence and accumulation of genus streptococci is critical to the development of a pathogenic plaque.…”

Analysis of interspecies adherence of oral bacteria using a membrane binding assay coupled with polymerase chain reaction‐denaturing gradient gel electrophoresis profiling

“…nucleatum and S. mutans were selected as oral representative bacterial species to study their co-adherence profiles within a salivary microbial community in more detail. Due to its ability to coaggregate with a variety of oral bacterial species, F. nucleatum is considered a "bridging organism" and has been suggested to play an important role in the development of oral microbial communities [4,8,34], while S. mutans is one of the early colonizers which can adhere to teeth surface by producing glucans and is generally regarded as a cariogenic bacterium [35][36][37]. We hypothesized that considering the different roles of these two bacterial species in dental plaque formation they could possess different co-adherence ability and have distinct interacting partners.…”

Responses of Cariogenic Streptococci to Environmental Stresses

“…S. mutans also produces an extracellular dextranase that attacks α1,6-linkages in the glucan products of the GTFs. The regulation of gtf and ftf gene, as well their importance in the virulence of S. mutans, has been well studied (Hudson and Curtiss, 1990;Li and Burne, 2001;Ooshima et al, 2001;Rozen et al, 2001;Sato and Kuramitsu, 1986;Shiroza and Kuramitsu, 1988;Steinberg et al, 2002). Also, GTFs are considered as primary candidates for a human caries vaccine (Childers et al, 2002;Jespersgaard et al, 1999;Michalek et al, 2001;Smith et al, 2001;Taubman et al, 2000).…”