Solution Structure of the NaV1.2 C-terminal EF-hand Domain
Solution Structure of the NaV1.2 C-terminal EF-hand Domain
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DOI：
10.1074/jbc.m807401200
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发表时间：
2009-03-06
影响因子：
4.8
通讯作者：
Palmer, Arthur G., III
中科院分区：
文献类型：
--
作者：
Miloushev, Vesselin Z.;Levine, Joshua A.;Palmer, Arthur G., III
电压门控钠通道在许多可兴奋组织中启动动作电位的快速上升。特定通道的细胞内C-末端序列内的突变是多种通道病的基础，包括心律失常和癫痫综合征。在pH7.4和290.5K的溶液中，用核磁共振波谱法测定了人Na（V）1.2电压门控钠通道C端1777-1882位残基的三维结构。有序结构从Leu-1790残基延伸至Glu-1868残基，由4个α-螺旋组成，由两条短的反平行β-链隔开;螺旋区从Ser-1869残基延伸至Arg-1882残基，螺旋区不太明确，N-末端区域包括残基1777-1789残基。虽然该结构具有成对EF-手结构域的整体架构，但Na（V）1.2 C-末端结构域不通过典型EF-手环结合Ca 2+，如通过在Ca 2+滴定期间监测H-1，N-15化学位移所证明的。还对Na（V）1.5（1773-1878）同种型进行了骨架化学位移共振归属和Ca 2+滴定，证明了相似的二级结构架构和EF-手环不存在Ca 2+结合。在Na（V）1钠通道的C-末端区域中鉴定的临床显著突变聚集在Na（V）1.2（1777-1882）结构的螺旋I-IV界面和螺旋II-III螺旋间片段或螺旋III和IV中。
Voltage-gated sodium channels initiate the rapid upstroke of action potentials in many excitable tissues. Mutations within intracellular C-terminal sequences of specific channels underlie a diverse set of channelopathies, including cardiac arrhythmias and epilepsy syndromes. The three-dimensional structure of the C-terminal residues 1777-1882 of the human Na(V)1.2 voltage-gated sodium channel has been determined in solution by NMR spectroscopy at pH 7.4 and 290.5 K. The ordered structure extends from residues Leu-1790 to Glu-1868 and is composed of four alpha-helices separated by two short anti-parallel beta-strands; a less well defined helical region extends from residue Ser-1869 to Arg-1882, and a disordered N-terminal region encompasses residues 1777-1789. Although the structure has the overall architecture of a paired EF-hand domain, the Na(V)1.2 C-terminal domain does not bind Ca2+ through the canonical EF-hand loops, as evidenced by monitoring H-1, N-15 chemical shifts during a Ca2+ titration. Backbone chemical shift resonance assignments and Ca2+ titration also were performed for the Na(V)1.5 (1773-1878) isoform, demonstrating similar secondary structure architecture and the absence of Ca2+ binding by the EF-hand loops. Clinically significant mutations identified in the C-terminal region of Na(V)1 sodium channels cluster in the helix I-IV interface and the helix II-III interhelical segment or in helices III and IV of the Na(V)1.2 (1777-1882) structure.