Studies on molecular organization, immunochemical characterization and biological activities of protein layers in bacterial surfaces

我们研究了一些梭状芽胞杆菌和乳酸菌外胞孔层中规律排列蛋白（RA蛋白）的分子结构、免疫化学性质和生物活性。1)电镜观察发现艰难梭菌细胞壁外层呈近方形排列，含有两种主要蛋白，Mrs分别为32和45 kDa，或38和42 kDa。两种RA蛋白的氨基酸组成和肽图存在差异。Ca^<2+>对于两种RA蛋白与尿素或盐酸胍溶解后的规则阵列的重组是必需的。32 kDa蛋白具有HeLa细胞的粘附活性，而45 kDa蛋白则没有。免疫电镜显示两种RA蛋白均存在于细胞孔表面。2)在E型肉毒杆菌外细胞壁层上观察到线性排列的薄阵列，由3种主要蛋白组成，Mrs分别为90、60和25 kDa。纯化90和60 kDa蛋白并进行免疫化学表征。免疫电镜显示这两种蛋白都位于细胞壁表面。3)在嗜酸乳杆菌群中，只有嗜酸乳杆菌群中存在规则排列，而在其他群中没有。根据RA蛋白的肽定位和免疫印迹，A组可进一步分为4个或更多亚群。

We have investigated the molecular organization, immunochemical properties, and biological activities of the regularly arranged proteins (RA proteins) in the outer cell well layers of some clostridia and lactobacilli. 1) The cell wall of clostridium difficile was revealed by electron microscopy to have an outer layer composed of a nearly square array and contained the two major proteins with Mrs of 32 and 45 kDa, or 38 and 42 kDa, depending on the strains. The amino acid composition and peptide maps of the two RA proteins differed from each other. Ca^<2+> was essential for the reassembly of regular array from the two RA proteins solubilized with urea or guanidine hydrochloride. The 32 kDa protein possessed the adhesive activity ot HeLa cells, whereas the 45 kDa protein did not. Immunoelectron microscopy revealed that the two RA proteins existed on the cell well surface. 2) A linearly arranged thin array was observed on the outer cell wall layer of Clostridium botulinum type E and composed of three major proteins with Mrs of 90, 60 and 25 kDa. The 90 and 60 kDa proteins were purified and immunochemically characterized. Both proteins were shown to locate on the wall surface by immunoelectron microscopy. 3) Regular arrays were present in only strains belonging to a group of lactobacillus acidophilus but not in the other groups. Based on the peptide mapping and immunoblotting of the RA proteins, the A group could be further classified into 4 or more subgroups.