CELL ADHERENCE OF DENTAL PLAQUE FORMING STREPTOCOCCI

变形链球菌的细胞能够顽强地附着在光滑的 并在蔗糖存在的情况下形成大的聚集体， 反映这种致龋性生物形成能力的特征 牙菌斑。黏附和聚集的生化介体 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 水不溶性葡聚糖与细胞黏附和斑块形成的关系 似乎是几种葡聚糖合成酶作用的结果。 变形链球菌中已鉴定出四种不同的葡萄糖转移酶 6715与单抗结合：两种GTF合成水溶性 葡聚糖(GTF-S1、S2和GTF-S4同工酶)及其两种合成 不溶于水的葡聚糖(GTF-11、13和GTF-12、14同工酶对)。广交会-S 酶在免疫学上是完全不同的，显著地合成 不同的1，6-α-D-葡聚糖对底物有不同的要求 右旋糖苷。GTF-I酶有一些共同的决定因素，但可以 与单抗不同，似乎产生了不同的 不溶于水的葡聚糖。我们发现变形链球菌也 产生一种葡聚糖分支酶，能够在细胞内形成分支 没有蔗糖，这是首次报道的这种酶。总而言之，广交会 同工酶和分支酶有可能形成复合体。 变形链球菌特有的胞外葡聚糖。这是一组复杂的 几种葡聚糖结合酶是葡聚糖合成酶的补充。 蛋白质，似乎缺乏酶活性。其中一些蛋白质是 胞外蛋白的主要成分补充，并可能作为 细胞表面上葡聚糖在黏附过程中的特异性结合部位 聚合。变形链球菌很早就知道会产生 内切酶，一种降解1，6，-α-D-葡聚糖的酶，抑制 变形链球菌酶促葡聚糖合成，阻断依赖蔗糖的细胞 表面附着力。然而，产生内切酶的变形链球菌 还会产生一种有效但可逆的内切酶抑制物，它 似乎是调节内切酶的一种细胞外方式 活动。这里建议和概述的研究针对的是 这几种蛋白质和酶在植物生长发育过程中的作用 变形链球菌葡聚糖合成和细胞黏附过程。对这件事 最后，我们正在开发针对和的单抗小组。 能够抑制这些蛋白质中的每一个的功能。

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.