Vordermeier M, Stäb K, Bessler W G
Infect Immun. 1986 Jan;51(1):233-9. doi: 10.1128/iai.51.1.233-239.1986.
Protein I from the outer membrane of Escherichia coli and other members of the family Enterobacteriaceae is a potent mitogen and polyclonal B-lymphocyte activator. To determine the part of the polypeptide responsible for biological activity, we cleaved the molecule into defined polypeptide fragments of approximate molecular weights 24,000, 15,000, 9,000, 7,000, and 3,000 by using the cyanogen bromide method. The fragments were purified by gel permeation chromatography and by preparative polyacrylamide gel electrophoresis. They were investigated for mitogenicity and for the induction of immunoglobulin synthesis in lymphocyte cultures from several inbred mouse strains. The fragment of molecular weight 24,000 turned out to be a potent polyclonal B-lymphocyte activator comparable to native protein I. The low-molecular-weight fragments exhibited only marginal effects. Neither purified T lymphocytes nor thymocytes were activated. Our results show that a defined fragment of protein I is responsible for its lymphocyte-stimulating activity.
来自大肠杆菌及肠杆菌科其他成员外膜的蛋白质I是一种强效促细胞分裂剂和多克隆B淋巴细胞激活剂。为了确定负责生物活性的多肽部分，我们使用溴化氰法将该分子切割成分子量约为24,000、15,000、9,000、7,000和3,000的特定多肽片段。通过凝胶渗透色谱法和制备性聚丙烯酰胺凝胶电泳对这些片段进行纯化。研究了它们在几种近交系小鼠品系的淋巴细胞培养物中的促有丝分裂活性以及诱导免疫球蛋白合成的能力。结果表明，分子量为24,000的片段是一种与天然蛋白质I相当的强效多克隆B淋巴细胞激活剂。低分子量片段仅表现出微弱的作用。纯化的T淋巴细胞和胸腺细胞均未被激活。我们的结果表明，蛋白质I的一个特定片段负责其淋巴细胞刺激活性。
