A new class of hexahelical insect proteins revealed as putative carriers of small hydrophobic ligands
A new class of hexahelical insect proteins revealed as putative carriers of small hydrophobic ligands
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DOI：
10.1016/s0969-2126(00)80022-2
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发表时间：
1999-11-15
期刊：
影响因子：
--
通讯作者：
Sönnichsen, FD
中科院分区：
文献类型：
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作者：
Rothemund, S;Liou, YC;Sönnichsen, FD
背景：THP12是来自黄粉虫的一种丰富且异常亲水的血淋巴蛋白，属于一组具有四个高度保守的半胱氨酸残基的小昆虫蛋白。尽管它们与气味结合蛋白和信息素结合蛋白具有序列同源性，但这些蛋白质的功能尚不清楚。结果：THP12的第一个三维结构已通过多维核磁共振波谱确定。该蛋白质具有由六个 a 螺旋组成的非束螺旋结构。 a螺旋的排列呈“棒球手套”形状。除了疏水核心之外，静电相互作用也有助于蛋白质的整体稳定性。 NMR 结合研究证明了小疏水性配体与 THP12 中的单个疏水性凹槽的结合。将 THP12 的结构与预测的同源物二级结构进行比较，揭示了这类新型昆虫蛋白的共同折叠。使用 DALI 程序进行的搜索显示，THP12 的三维结构与恢复素（钙结合 EF-hand 蛋白家族的成员）的 N 端结构域（残基 1-95）之间存在广泛的相似性。 结论：虽然这一类新蛋白的生物学功能尚未确定，但作为小疏水性配体的 a 螺旋载体蛋白的一般作用，例如 脂肪酸或信息素，是在核磁共振位移微扰光谱的基础上提出的。
Background: THP12 is an abundant and extraordinarily hydrophilic hemolymph protein from the mealworm Tenebrio molitor and belongs to a group of small insect proteins with four highly conserved cysteine residues. Despite their sequence homology to odorant-binding proteins and pheromone-binding proteins, the function of these proteins is unclear.Results: The first three-dimensional structure of THP12 has been determined by multidimensional NMR spectroscopy. The protein has a nonbundle helical structure consisting of six a helices. The arrangement of the a helices has a 'baseball glove' shape. In addition to the hydrophobic core, electrostatic interactions make contributions to the overall stability of the protein. NMR binding studies demonstrated the binding of small hydrophobic ligands to the single hydrophobic groove in THP12. Comparing the structure of THP12 with the predicted secondary structure of homologs reveals a common fold for this new class of insect proteins. A search with the program DALI revealed extensive similarity between the three-dimensional structure of THP12 and the N-terminal domain (residues 1-95) of recoverin, a member of the family of calcium-binding EF-hand proteins.Conclusions: Although the biological function of this new class of proteins is as yet undetermined, a general role as a-helical carrier proteins for small hydrophobic ligands, such as fatty acids or pheromones, is proposed on the basis of NMR-shift perturbation spectroscopy.