CELL ADHERENCE OF DENTAL PLAQUE FORMING STREPTOCOCCI

变形链球菌的细胞能够顽强地粘附在光滑的 表面并在蔗糖存在下形成大的聚集体， 反映这种致龋微生物形成 牙菌斑 粘附和聚集的生化介质 存在于一组葡聚糖合成酶（葡糖基转移酶， GTF）和葡聚糖结合蛋白。 的复杂结构 与细胞粘附和斑块形成有关的水不溶性葡聚糖 似乎是由几种葡聚糖合成酶的作用引起的。 在S.变异株 6715单克隆抗体：两种GTF合成水溶性 葡聚糖（同工酶GTF-S1、S2和GTF-S4）和两种合成 水不溶性葡聚糖（同工酶对GTF-11，13和GTF-12，14）。 GTF-S 酶在免疫学上是完全不同的， 不同的1，6-α-D-葡聚糖，对引物的要求也不同 葡聚糖 GTF-I酶共享一些决定簇，但可以是 与单克隆抗体分化，并似乎产生不同的 水不溶性葡聚糖。 我们发现变形链球菌也 产生葡聚糖分支酶，其能够在所述细胞中形成分支， 不存在蔗糖，这是第一个报道的这种酶。 GTF一起 同工酶和分支酶具有形成复合物的潜力 胞外葡聚糖是S.变异人 复群 葡聚糖合成酶由几种葡聚糖结合酶补充 蛋白质，似乎缺乏酶活性。 其中一些蛋白质是 细胞外蛋白补体的主要成分， 在粘附过程中葡聚糖特异性结合的细胞表面位点， 聚合来 变形链球菌长期以来一直被认为可以产生 内切葡聚糖酶是一种降解1，6-α-D-葡聚糖的酶， 葡聚糖的合成。变形酶，并阻止蔗糖依赖性细胞， 表面附着力 然而，S.产生内切葡聚糖酶的变异菌株 还产生一种有效但可逆的内葡聚糖酶抑制剂， 似乎是调节内葡聚糖酶的细胞外手段 活动 这里提出和概述的研究是针对 确定这几种蛋白质和酶的作用， 葡聚糖合成和细胞粘附的过程。变异人 本 最后，我们正在开发的单克隆抗体面板， 能够抑制这些蛋白质中每一种的功能。

The cells of Streptococcus mutans are able to adhere tenaciously to smooth surfaces and form large aggregates in the presence of sucrose, characteristiCs reflecting the ability of this cariogenic organism to form dental plaque. The biochemical mediators of adherence and aggregation reside in a group of glucan-synthesizing enzymes (glucosyltransferases, GTF) and glucan-binding proteins. The complex structure of the water-insoluble glucans implicated in cell adherence and plaque formation appears to result from the actions of several glucan-synthesizing enzymes. Four distinct glucosyltransferases have been identified in S. mutans strain 6715 with monoclonal antibodies: Two GTF synthesizing water-soluble glucans (isozymes GTF-S1,S2 and GTF-S4) and two synthesizing water-insoluble glucans (isozyme pairs GTF-11,13 and GTF-12,14). The GTF-S enzymes are completely distinct immunologically, synthesize markedly different 1,6-Alpha-D-glucans and have different requirements for primer dextran. The GTF-I enzymes share some determinants but can be differentiated with monoclonal antibodies and appear to produce different water-insoluble glucans. We have found that Streptococcus mutans also produces a dextran-branching enzyme capable of forming branches in the absence of sucrose, the first such enzyme reported. Together, the GTF isozymes and the branching enzyme have the potential to form the complex extracellular glucans characteristic of S. mutans. Thic complex group of glucan-synthesizing enzymes is complemented by several glucan-binding proteins, which seem to lack enzyme activity. Some of these proteins are major components of the extracellular protein complement and may serve as cell-surface sites for specific binding of glucan during adherence and aggregation. Streptococcus mutans has long been known to produce endodextranase, an enzyme which degrades 1,6,-Alpha-D-glucans, inhibits glucan synthesis by S. mutans enzymes, and blocks sucrose-dependent cell to surface adherence. However, S. mutans strains which produce endodextranase also produce a potent but reversible inhibitor of endodextranase, which appears to be an extracellular means for modulation of endodextranase activity. The studies proposed and outlined here are directed to the determination of the roles of these several proteins and enzymes in the processes of glucan synthesis and cell adherence by S. mutans. To this end, we are developing panels of monoclonal antibodies specific for and capable of inhibiting the function of each of these proteins.