Three-dimensional solution structure of mu-conotoxin GIIIB, a specific blocker of skeletal muscle sodium channels
Three-dimensional solution structure of mu-conotoxin GIIIB, a specific blocker of skeletal muscle sodium channels
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DOI：
10.1021/bi960073o
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发表时间：
1996-07-09
期刊：
影响因子：
2.9
通讯作者：
Craik, DJ
中科院分区：
文献类型：
--
作者：
Hill, JM;Alewood, PF;Craik, DJ
用2D H-1 NMR光谱法测定了食鱼锥螺Conus geographus毒液中的22个残基多肽μ-芋螺毒素GIIIB的三维溶液结构。GIIIB以高亲和力和选择性与骨骼肌钠通道结合，是表征这些通道结构和功能的有价值的工具。由NOE推断的289个质子间距离和由自旋-自旋耦合常数推断的9个主链和5个侧链二面角约束组成的结构约束被用作X-PLOR程序中的模拟退火计算和能量最小化的输入。除了H-1 NMR衍生的信息之外，GIIIB的C-13共振被指定为天然丰度，羟脯氨酸C β和C γ化学位移用于区分顺式和反式肽键构象。最后一组20个结构在整个分子上具有平均成对rms差，骨架原子为1.22埃，所有重原子为2.48埃。对于包括残基3-21的明确限定的区域，相应的值分别为0.74和2.54埃。GIIIB采用由扭曲的3（10）-螺旋、小的β-发夹、顺式-羟脯氨酸和几个转角组成的紧凑结构。该分子通过三个二硫键稳定，其中两个连接螺旋和β-折叠，形成与CS α β基序相似的结构核心[Comet，B.，Bonmatin，J. M.，Hetru角，霍夫曼，J. A.，Ptak，M.，& Vovelle，F.（1995）Structure 3，435-448]，该基序对于包括蝎毒素和昆虫防御素的几个小蛋白家族是共同的。GIIIB的其他结构特征包括存在八个精氨酸和赖氨酸侧链，其相对于分子的核心以径向取向突出到溶剂中。这些阳离子侧链与钠通道上的阴离子位点形成潜在的相互作用位点。的全球折叠是相似的，报告的μ-芋螺毒素GIIIA，和GIIIB的结构，在这项研究中确定的μ-芋螺毒素的结构-活性关系的进一步理解和他们的结合骨骼肌钠通道提供了基础。
The three-dimensional solution structure of mu-conotoxin GIIIB, a 22-residue polypeptide from the venom of the piscivorous cone snail Conus geographus, has been determined using 2D H-1 NMR spectroscopy. GIIIB binds with high affinity and selectivity to skeletal muscle sodium channels and is a valuable tool for characterizing both the structure and function of these channels. Structural restraints consisting of 289 interproton distances inferred from NOEs and 9 backbone and 5 side chain dihedral angle restraints from spin-spin coupling constants were used as input for simulated annealing calculations and energy minimization in the program X-PLOR, In addition to the H-1 NMR derived information, the C-13 resonances of GIIIB were assigned at natural abundance, and hydroxyproline C beta and C gamma chemical shifts were used to distinguish between the cis and trans peptide bond conformations. The final set of 20 structures had mean pairwise rms differences over the whole molecule of 1.22 Angstrom for the backbone atoms and 2.48 Angstrom for all heavy atoms. For the well-defined region encompassing residues 3-21, the corresponding values were 0.74 and 2.54 Angstrom, respectively. GIIIB adopts a compact structure consisting of a distorted 3(10)-helix, a small beta-hairpin, a cis-hydroxyproline, and several turns. The molecule is stabilized by three disulfide bonds, two of which connect the helix and the beta-sheet, forming a structural core with similarities to the CS alpha beta motif [Comet, B., Bonmatin, J.-M., Hetru, C., Hoffmann, J. A., Ptak, M., & Vovelle, F. (1995) Structure 3, 435-448], This motif is common to several families of small proteins including scorpion toxins and insect defensins. Other structural features of GIIIB include the presence of eight arginine and lysine side chains that project into the solvent in a radial orientation relative to the core of the molecule. These cationic side chains form potential sites of interaction with anionic sites on sodium channels. The global fold is similar to that reported for mu-conotoxin GIIIA, and the structure of GIIIB determined in this study provides the basis for further understanding of the structure-activity relationships of the mu-conotoxins and for their binding to skeletal muscle sodium channels.