Molecular analysis of gloom-binding Protein in canes Pathogenesis of S. mutans

变形链球菌被认为是人类龋齿的主要病原体。与变形链球菌粘附期相关的细菌成分包括葡萄糖基转移酶、蛋白抗原c和结合葡聚糖的蛋白。至少已鉴定出四种葡聚糖结合蛋白(GBP)：GbpA、GbpB、Gbpc和GbpD。在我们以前的研究中，已经研究了GbpA和Gbpc在变形链球菌毒力中的作用，但GbpB的生物学功能及其在变形链球菌毒力中的作用尚不清楚。利用一株GbpB缺失突变株(Bd1)，我们在本研究中证明了GbpB在变形链球菌生物学中的作用。BD1的生长速度低于其他菌株，但对吞噬作用的敏感性也低于亲本菌株MT8148，并形成更长的链。此外，对Bd1细胞表面的电子显微镜观察显示，细胞壁的细胞层不明显。这些结果表明，GbpB可能在细胞壁的构建中起重要作用，并参与细胞的分离和维持。

Streptococcus mutans has been implicated as a major causative agent of dental caries in humans. Bactreial components associated with the adhesion phase of S. mutans include glucosyltransferase, protein antigen c, and proteins that bind glucan. At least four glucan-binding proteins (Gbp) have been identified; GbpA, GbpB, GbpC, and GbpD. In our previous study,the contributions of GbpA and GbpC to the virulence of S. mutans were investigated; however, the biological function of GbpB and its role in the virulence of S. mutans remain to be elucidated. Using a GbpB-deficient mutant strain (BD1), we demonstrated in the present study that GbpB has a role in the biology of S. mutans. The growth rate of BD1 was lower than that of other strains, while it was also shown to be less susceptible to phagocytosis and to form longer chains than the parental strain MT8148. In addition, electron microscope observations of the cell surfaces of BD1 showed that call-wall layers were obscure. These results suggest that GbpB may have an important role in the cell-wall construction and be involved in cell separation and cell maintenance.