Flores A E, Ferrieri P
Department of Laboratory Medicine, University of Minnesota Medical School, Minneapolis, USA.
Zentralbl Bakteriol. 1996 Sep;285(1):44-51. doi: 10.1016/s0934-8840(96)80021-1.
The alpha (alpha) component of the c protein and R proteins are trypsin resistant, but antigenically distinct, proteins on the cell surface of some but not all strains of group B streptococci (GBS). These two classes of proteins, along with the group and type polysaccharide, can be used to characterize strains of GBS. Four species of R protein (R1 through R4) have been described. We studied trypsin extracts from numerous strains of GBS by immunodiffusion in agarose and polyacrylamide gel electrophoresis/Western blot. Sera monospecific for alpha, R1 and R4 were used to immunoprecipitate/blot the proteins. The molecular weight of the blotted proteins was determined. Although by immunodiffusion the proteins within a class were identical to each other, great heterogeneity in size and blotting pattern was found within each class. Variation was independent of the polysaccharide serotype. Multiple molecular weight species were seen for alpha, R1 and R4 proteins. For a given strain, the various forms of alpha or R1 appeared to form a multiple size ladder; those of R4 were fewer and closer in size. The highest form of alpha ranged from 85 to 170 kDa, with 45 kDa being the highest form for some rare GBS strains. For R4 the predominant and highest form varied from 84 to 197 kDa, whereas some strains with R1 had the highest form over 200 kDa. Our results indicated that despite similarities, there is great diversity among the alpha, R1 and R4 trypsin resistant proteins of GBS.
C蛋白和R蛋白的α（阿尔法）组分是B族链球菌（GBS）部分（而非全部）菌株细胞表面上对胰蛋白酶具有抗性但抗原性不同的蛋白质。这两类蛋白质，连同群特异性多糖和型特异性多糖，可用于鉴定GBS菌株。已描述了四种R蛋白（R1至R4）。我们通过琼脂糖免疫扩散和聚丙烯酰胺凝胶电泳/蛋白质印迹法研究了众多GBS菌株的胰蛋白酶提取物。使用对α、R1和R4单特异性的血清对蛋白质进行免疫沉淀/印迹。测定了印迹蛋白质的分子量。尽管通过免疫扩散同一类中的蛋白质彼此相同，但在每一类中发现大小和印迹模式存在很大异质性。这种变异与多糖血清型无关。α、R1和R4蛋白出现了多种分子量的种类。对于给定菌株，α或R1的各种形式似乎形成了一个多大小的梯状条带；R4的条带较少且大小更接近。α的最高形式范围为85至170 kDa，对于一些罕见的GBS菌株，45 kDa是最高形式。对于R4，主要和最高形式从84至197 kDa不等，而一些具有R1的菌株最高形式超过200 kDa。我们的结果表明，尽管存在相似性，但GBS的α、R1和R4对胰蛋白酶具有抗性的蛋白质之间存在很大差异。
