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 protein C,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 UA159 GbpC C 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 UA159GbpC C 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;免疫印迹可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。
Each secretion(Sec)machinery minimally consists of three integral inner membrane pro- teins SecYEG.In order to know the distribution pattern of the Sec complex in Streptococcus mutans,we explored the subcellular localization of SecY.The anti-secY antibody was examined on Western blots to evaluate specificity.An indirect post-embedding immunogold method was used to determine the subcel- lular localization of the SecY in the cytoplasmic membrane of the Streptococcus mutans GS-5.Immuno- blotting experiments showed that the anti-secY antibody specifically recognized a single band of about 47.8 kDa.Immunogold electron microscopy image of section with anti-secY antibody revealed a single intense focus of gold particles at a discrete location on the cytoplasmic membrane of the Streptococcus mutans GS-5.SecY clustered to an asyrmnetric microdomain,which indicated for the first time that Sec complex presented a uni-site on the cytoplasmic membrane of Streptococcus mutans.
