Crystal structure of the soluble form of equinatoxin II, a pore-forming toxin from the sea anemone Actinia equina
Crystal structure of the soluble form of equinatoxin II, a pore-forming toxin from the sea anemone Actinia equina
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DOI：
10.1016/s0969-2126(01)00592-5
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发表时间：
2001-04-07
期刊：
影响因子：
5.7
通讯作者：
Turk, D
中科院分区：
文献类型：
--
作者：
Athanasiadis, A;Anderluh, G;Turk, D
背景资料：膜孔形成毒素具有显著的性质：它们采用稳定的可溶形式结构，当与膜接触时，其经历一系列转化，导致活性的膜结合形式。与细菌毒素相比，没有结构的成孔毒素从真核生物已被确定到目前为止，这表明结构研究的马眼毒素II（EqtII）可能解开一个新的mechanism.Results：的晶体结构的可溶性形式的EqtII从海葵Actinia马已被确定在1.9埃分辨率。EqtII被证明是一个单结构域的蛋白质的基础上的12链β夹心折叠与疏水性核心和一对CT螺旋，其中每个是与13片的面。结论：30 N-末端残基的结构是最大的部分，可以采用不同的结构，而不破坏折叠的β夹心核心。该片段包括位于β折叠表面的三圈α螺旋，并以三个带正电荷的残基Lys-30、Arg-31和Lys-32的延伸结束。收集的数据的基础上，它表明，这段形成膜孔，而β夹心结构保持不变，并连接到膜上做其他结构相关的外源性膜蛋白或其结构域。使用结构数据定点诱变研究应揭示参与膜孔形成的残基。
Background: Membrane pore-forming toxins have a remarkable property: they adopt a stable soluble form structure, which, when in contact with a membrane, undergoes a series of transformations, leading to an active, membrane-bound form. In contrast to bacterial toxins, no structure of a pore-forming toxin from an eukaryotic organism has been determined so far, an indication that structural studies of equinatoxin II (EqtII) may unravel a novel mechanism.Results: The crystal structure of the soluble form of EqtII from the sea anemone Actinia equina has been determined at 1.9 Angstrom resolution. EqtII is shown to be a single-domain protein based on a 12 strand beta sandwich fold with a hydrophobic core and a pair of ct helices, each of which is associated with the face of a 13 sheet.Conclusions: The structure of the 30 N-terminal residues is the largest segment that can adopt a different structure without disrupting the fold of the beta sandwich core. This segment includes a three-turn a helix that lies on the surface of a beta sheet and ends in a stretch of three positively charged residues, Lys-30, Arg-31, and Lys-32. On the basis of gathered data, it is suggested that this segment forms the membrane pore, whereas the beta sandwich structure remains unaltered and attaches to a membrane as do other structurally related extrinsic membrane proteins or their domains. The use of a structural data site-directed mutagenesis study should reveal the residues involved in membrane pore formation.