中文摘要：

目的探索C端结构变异为亮氨酸-脯氨酸-任意氨基酸-丙氨酸-甘氨酸（LPXAG）的葡聚糖结合蛋白C（glucan binding proteinC，GbpC）是否在变形链球菌UA159的细胞壁上。方法用PCR法扩增变形链球菌UA159GbpCC端的编码基因片段，推测和分析C端氨基酸序列组成；分别提取上清蛋白、胞内蛋白和胞壁蛋白，用Western blot法在变形链球菌UA159各成分中检测GbpC；用免疫金标直接观察GbpC的表达位置；应激条件下进行多聚糖依赖黏附实验。结果变形链球菌UA159GbpCC端亮氨酸-脯氨酸-任意氨基酸-苏氨酸-甘氨酸（LPXTG）的结构变异为LPXAG；免疫印迹叮以在细菌的壁蛋白中检测到GbpC；电镜下可以观察到金颗粒围绕细菌细胞壁聚集；变形链球菌UA159在应激条件下表现为多糖依赖黏附实验阳性。结论C端为LPXAG的GbpC仍然锚定在细菌的细胞壁上。

英文摘要：

Objective To determine whether the glucan binding protein C （GbpC） with LPXAG motif is anchoring to the cell wall of the Streptococcus mutans UA159 （S. mutans UA159 ）. Methods S. mutans UA159 GbpC C terminal gene segment was amplified by PCR , the gene sequences and the deduced amino acid sequences were analyzed. In order to locate the GbpC of S. mutans, the study isolated the wall fraction following digestion of the cell wall by N-acetylmuramidase, and the GbpC was detected by Western blot analysis. GbpC S. mutans UA159 was located with gold particles. Furthermore, the dextrandependent aggregation （ddag） phenotype of the S. mutans UA159 under stress condition was observed. Results S. mutans UA159 GbpC C-terminal LPXTG motif was replaced by LPXAG motif. GbpC was observed in the cell wall component and immunogold experiment showed that the gold particles distributed around the cell wall surface. S. mutans UA159 exhibited ddag ＋. Conclusions GbpC with LPXAG motif was still anchoring to the cell wall.