Proteome Analysis of Surface Protein of Cariogenic Bacteria Influenced to Formation of Biofilm

我们对菌斑生物膜形成的变形链球菌的表面蛋白进行了分析，得到了以下结果。通过聚合酶链式反应和反向聚合酶链式反应，扩增了变形链球菌109c的索尔特酶基因(SrtA)，并将其克隆到pT7 Blue T载体中。然后确定了完整的核苷酸序列。根据核苷酸序列插入失活的方法构建了变形链球菌109c的srtA缺失突变株(srtA^-)。用特异性抗血清进行Western印迹分析表明，SrtA介导了表面蛋白抗原(PAC)、葡聚糖结合蛋白C(GBPC)和葡聚糖酶(Dex)等表面蛋白的细胞定位。比较了变形链球菌野生型(109c)和srtA^-菌斑生物膜的形成能力。在葡聚糖存在下，srtA^-失去了依赖葡聚糖聚集和形成水不溶性粘附性葡聚糖的能力。这些结果表明，srtA介导至少3种变形链球菌表面蛋白(Pac、GbpG、Dex)的细胞定位，并控制这些蛋白的生理功能(形成致龋性生物膜)。这些现象似乎不仅是srtA基因失活的结果，也是变形链球菌srtA酶被抑制的结果。因此，变形链球菌的srtA可能是预防生物膜形成和随后的龋病的一个有吸引力的靶点。

We analyzed surface proteins of Streptococcus mutans responsible for formation of plaque biofilm and obtained the following results. The sortase gene (srtA) of S. mutans 109c was amplified by PCR and inverse PCR and cloned into pT7 blue T-vector. The complete nucleotide sequence was then determined. A srtA-deficient mutant (SrtA^-) of S.mutans 109c was constructed by insertional inactivation on the basis of the nucleotide sequence. Western blot analysis with specific antiserum demonstrated that the SrtA mediated cell localization of surface proteins such as a surface protein antigen (PAc), a glucan-binding protein C (GbpC) and a dextranase (Dex). The ability of plaque-biofilm formation of the wild type (109c) and the SrtA^-of S.mutans was then compared. The SrtA^-lost the abilities for both glucan-dependent aggregation under the presence of dextran and formation of water-insoluble adhesive glucan. These results suggested that the SrtA mediates cell-localization of at least 3 surface proteins (PAC, GbpG, Dex) of S.mutans and controls physiological functions (formation of caries-inducible biofilm) of those proteins. These phenomena appear to expect not only as the result of inactivation of the srtA gene but also due to the inhibition of the SrtA enzyme of S.mutans. SrtA of S.mutans could therefore be an attractive target for the prevention of biofilm formation and subsequent dental caries.