Assembly mechanism of the oligomeric streptolysin O pore: the early membrane lesion is lined by a free edge of the lipid membrane and is extended gradually during oligomerization
Assembly mechanism of the oligomeric streptolysin O pore: the early membrane lesion is lined by a free edge of the lipid membrane and is extended gradually during oligomerization
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DOI：
10.1093/emboj/17.6.1598
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发表时间：
1998-03-16
期刊：
影响因子：
11.4
通讯作者：
Bhakdi, S
中科院分区：
文献类型：
--
作者：
Palmer, M;Harris, R;Bhakdi, S
链球菌溶血素O（SLO）是一种细菌外毒素，它与含有胆固醇的细胞膜结合，然后寡聚形成大孔。沿着环，在膜上形成弧形低聚物，已经提出每个代表不完全组装的低聚物，并构成功能孔，在相对侧面对脂质膜的自由边缘。我们寻求功能的证据支持这一想法，通过使用寡聚化缺陷，非裂解突变的SLO。这种蛋白质是通过用N-（碘乙酰氨基乙基）-1-萘胺-5-磺酸化学修饰单个突变半胱氨酸（T250 C）而产生的，其在膜上形成具有活性SLO的杂合寡聚体。然而，掺入修饰的T250 C突变体抑制了随后的寡聚化，使得杂交寡聚体的大小减小。这些在电子显微镜下表现为典型的损伤，它们形成允许NaCl和钙黄绿素通过但限制大葡聚糖分子渗透的孔。这些数据表明，SLO孔是在寡聚化过程中逐渐形成的，这意味着在质膜中可能会产生一侧由蛋白质内衬而另一侧由游离脂质边缘内衬的孔。有意操纵的孔径大小可能会扩大SLO的效用作为一种工具，在细胞生物学实验。
Streptolysin O (SLO) is a bacterial exotoxin that binds to cell membranes containing cholesterol and then oligomerizes to form large pores. Along with rings, are-shaped oligomers form on membranes, It has been suggested that each are represents an incompletely assembled oligomer and constitutes a functional pore, faced on the opposite side by a free edge of the lipid membrane. We sought functional evidence in support of this idea by using an oligomerization-deficient, nonlytic mutant of SLO. This protein, which was created by chemical modification of a single mutant cysteine (T250C) with N-(iodoacetaminoethyl)-1-naphthylannine-5-sulfonic acid, formed hybrid oligomers with active SLO on membranes. However, incorporation of the modified T250C mutant inhibited subsequent oligomerization, so that the hybrid oligomers were reduced in size. These appeared as typical are lesions in the electron microscope, They formed pores that permitted passage of NaCl and calcein but restricted permeation of large dextran molecules. The data indicate that the SLO pore is formed gradually during oligomerization, implying that pores lined by protein on one side and an edge of free lipid on the other may be created in the plasma membrane. Intentional manipulation of the pore size may extend the utility of SLO as a tool in cell biological experiments.