Subtype specificity of scorpion β-toxin Tz1 interaction with voltage-gated sodium channels is determined by the pore loop of domain 3
Subtype specificity of scorpion β-toxin Tz1 interaction with voltage-gated sodium channels is determined by the pore loop of domain 3
复制标题
DOI：
10.1124/mol.106.024034
复制
发表时间：
2006-07-01
影响因子：
3.6
通讯作者：
Heinemann, Stefan H.
中科院分区：
文献类型：
--
作者：
Leipold, Enrico;Hansel, Alfred;Heinemann, Stefan H.
电压门控钠（Na-v）通道由多种特异性神经毒素调节。蝎β-毒素影响通道门控的电压依赖性：在它们的存在下，Na-v通道在亚阈值膜电压下激活。先前的诱变研究已经揭示，β-毒素Css 4与Na-γ通道的结构域2中的区段3和4之间的细胞外接头相互作用，具有将该电压传感器捕获在开放位置的效果（Neuron 21：919-931，1998）。因此，域2的电压传感器被鉴定为构成神经毒素受体位点4的主要部分。在这项工作中，我们研究了来自委内瑞拉蝎Tityus zulianus的β-毒素Tz 1对HEK 293细胞中表达的各种哺乳动物Na-v通道类型的影响。虽然骨骼肌通道（Na-v 1.4）受到Tz 1的强烈影响，但神经元通道Na-v 1.6和Na-v 1.2的敏感性较低，心脏Na-v 1.5和外周神经通道Na-v 1.7基本上不敏感。对其中Na-v 1.2的整个结构域插入Na-v 1.4背景中的通道嵌合体的分析揭示，Na-v 1.2表型不是由结构域2而是由结构域3赋予Na-v 1.4的。相互作用表位可以缩小到位于结构域3中的C-末端孔环中的残基Glu 1251、Lys 1252和His 1257。因此，β-毒素与Na-v通道相互作用的受体位点跨越结构域2和3，其中结构域3中的孔环规定了单个神经元Nav通道类型的药理学性质。
Voltage-gated sodium (Na-v) channels are modulated by a variety of specific neurotoxins. Scorpion beta-toxins affect the voltage-dependence of channel gating: In their presence, Na-v channels activate at subthreshold membrane voltages. Previous mutagenesis studies have revealed that the beta-toxin Css4 interacts with the extracellular linker between segments 3 and 4 in domain 2 of Na-v channels with the effect to trap this voltage sensor in an open position (Neuron 21: 919-931, 1998). The voltage sensor of domain 2 was thus identified to constitute a major part of neurotoxin receptor site 4. In this work, we studied the effects of the beta-toxin Tz1 from the Venezuelan scorpion Tityus zulianus on various mammalian Na-v channel types expressed in HEK 293 cells. Although skeletal muscle channels (Na-v 1.4) were strongly affected by Tz1, the neuronal channels Na-v 1.6 and Na-v 1.2 were less sensitive, and the cardiac Na-v 1.5 and the peripheral nerve channel Na-v 1.7 were essentially insensitive. Analysis of channel chimeras in which whole domains of Na-v 1.2 were inserted into a Na-v 1.4 background revealed that the Na-v 1.2 phenotype was not conferred to Na-v 1.4 by domain 2 but by domain 3. The interaction epitope could be narrowed down to residues Glu1251, Lys1252, and His1257 located in the C-terminal pore loop in domain 3. The receptor site for beta-toxin interaction with Na-v channels thus spans domains 2 and 3, where the pore loop in domain 3 specifies the pharmacological properties of individual neuronal Nav channel types.