On the convergent evolution of animal toxins - Conservation of a diad of functional residues in potassium channel-blocking toxins with unrelated structures
On the convergent evolution of animal toxins - Conservation of a diad of functional residues in potassium channel-blocking toxins with unrelated structures
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DOI：
10.1074/jbc.272.7.4302
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发表时间：
1997-02-14
影响因子：
4.8
通讯作者：
Menez, A
中科院分区：
文献类型：
--
作者：
Dauplais, M;Lecoq, A;Menez, A
BGK是一种来自海葵Bunodosoma ranulifera的K+通道阻断毒素。根据核磁共振和建模，它是一个37个残基的蛋白质，采用了一个新的折叠。基于丙氨酸扫描的分析揭示了五个残基的功能重要性，其中包括一个关键的赖氨酸和一个芳香族残基，它们之间的距离为6.6+/-1.0埃。在已知的三种来自海葵的同源毒素中也发现了同样的二联体。更引人注目的是，所有来自蝎子的K+通道阻断毒素中都存在一个类似的功能二联体，尽管这些毒素采用了不同的支架。此外，来自海葵和蝎子的钾通道阻断毒素的功能二重体叠加在三维结构中。因此，结构不相关但功能相似的毒素具有保守的关键功能残基，组织在相同的拓扑结构中，这表明这些小蛋白的功能进化是收敛的。
BgK is a K+ channel-blocking toxin from the sea anemone Bunodosoma granulifera. It is a 37-residue protein that adopts a novel fold, as determined by NMR and modeling. An alanine-scanning-based analysis revealed the functional importance of five residues, which include a critical lysine and an aromatic residue separated by 6.6 +/- 1.0 Angstrom. The same diad is found in the three known homologous toxins from sea anemones. More strikingly, a similar functional diad is present in all K+ channel-blocking toxins from scorpions, although these toxins adopt a distinct scaffold. Moreover, the functional diads of potassium channel-blocking toxins from sea anemone and scorpions superimpose in the three-dimensional structures. Therefore, toxins that have unrelated structures but similar functions possess conserved key functional residues, organized in an identical topology, suggesting a convergent functional evolution for these small proteins.