Benz R, Hardie K R, Hughes C
Lehrstuhl für Biotechnologie, Theodor-Boveri-Institut (Biozentrum), Universität Würzburg, Germany.
Eur J Biochem. 1994 Mar 1;220(2):339-47. doi: 10.1111/j.1432-1033.1994.tb18630.x.
Lipid-bilayer experiments were performed with the related hemolysins from Proteus vulgaris and Morganella morganii (HlyA). The addition of the toxins to the aqueous phase bathing lipid-bilayer membranes composed of different lipids resulted in the formation of transient ion-permeable channels. Membranes formed of pure lipids were rather inactive targets for the hemolysins as compared with lipid mixtures such as asolectin. The channels had several different substrates. The major open state had single-channel conductances of 500 pS in 0.15 M KCl at small transmembrane voltages. Experiments with different salts suggested that the hemolysin-induced channels of P. vulgaris and M. morganii were exclusively cation selective at neutral pH, caused by negative charges localized at the channel mouth. The mobility sequence of the cations within the channels was similar if not identical to their mobility sequence in the aqueous phase. The single-channel data were consistent with wide, water-filled channels with estimated minimal diameters of about 1 nm since the large organic cation Tris+ can permeate the channels without any detectable interaction with its interior. Pore-forming properties of these hemolysins were compared with those of HlyA of Escherichia coli. All these toxins share common features, oligomerize probably to form pores in lipid-bilayer membranes and form channels with similar properties which suggests that their structures are more or less identical.
利用普通变形杆菌和摩根氏摩根菌的相关溶血素（HlyA）进行了脂质双层实验。将毒素添加到浸泡由不同脂质组成的脂质双层膜的水相中，会导致形成瞬时离子通透通道。与诸如大豆卵磷脂等脂质混合物相比，由纯脂质形成的膜对溶血素而言是相当不活跃的靶标。这些通道有几种不同的底物。在小跨膜电压下，主要开放状态在0.15 M KCl中的单通道电导为500 pS。用不同盐进行的实验表明，普通变形杆菌和摩根氏摩根菌的溶血素诱导的通道在中性pH下完全对阳离子具有选择性，这是由位于通道口的负电荷所致。通道内阳离子的迁移序列与其在水相中的迁移序列相似（若不是完全相同的话）。单通道数据与宽的、充满水的通道一致，估计其最小直径约为1 nm，因为大的有机阳离子Tris⁺可以穿过通道，而与其内部没有任何可检测到的相互作用。将这些溶血素的成孔特性与大肠杆菌的HlyA的成孔特性进行了比较。所有这些毒素都具有共同特征，可能会寡聚以在脂质双层膜中形成孔，并形成具有相似特性的通道，这表明它们的结构或多或少是相同的。
