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首页> 外文期刊>Biochemistry >DESIGN OF HETEROTETRAMERIC COILED COILS - EVIDENCE FOR INCREASED STABILIZATION BY GLU(-)-LYS(+) ION PAIR INTERACTIONS
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DESIGN OF HETEROTETRAMERIC COILED COILS - EVIDENCE FOR INCREASED STABILIZATION BY GLU(-)-LYS(+) ION PAIR INTERACTIONS

机译:异四聚体卷曲螺旋的设计-证据表明通过GLU(-)-LYS(+)离子对相互作用增强了稳定性

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Electrostatic interactions between charged amino acids often affect heterospecificity in coiled coils as evidenced by the interaction between the oncoproteins, fos and jun. Such interactions have been successfully exploited in the design of heteromeric coiled coils in a number of laboratories, It has been suggested that heterospecificity in these dimeric coiled-coil systems is driven not by specific electrostatic interactions in the heterodimers but rather by electrostatic repulsion acting to destabilize the homodimer state relative to the heterodimer state. We show that it is possible to design ion pair interactions that directly stabilize the heterotetrameric coiled-coil state. Synthetic peptides were used whose sequences are based on the C-terminal tetramerization domain of Lac repressor, as a model system for four-chain coiled coils (Fairman et al., 1995). These Lac-based peptides, containing either glutamic acid (Lac21E) or lysine (Lac21K) at all b and c heptad positions, only weakly self-associate but, when mixed, afford a highly stable heterotetramer. This study represents the first experimental evidence for the importance of the b and c heptad positions to the stability of coiled coils. Finally, pH dependence and NaCl dependence studies show that heterotetramer stability is driven by ion pair interactions between glutamate and lysine; these interactions contribute about 0.6 kcal/mol of stabilizing free energy for each potential glutamate-lysine pair.
机译:癌蛋白,fos和jun之间的相互作用证明,带电氨基酸之间的静电相互作用通常会影响卷曲螺旋的异种特异性。在许多实验室中,这种相互作用已被成功地用于异源卷曲螺旋的设计中。已经表明,这些二聚卷曲螺旋系统中的异专一性不是由异二聚体中的特定静电相互作用驱动,而是受静电排斥作用破坏相对于异二聚体状态的同二聚体状态。我们表明,可以设计直接稳定异四聚体卷曲螺旋状态的离子对相互作用。使用的合成肽的序列基于Lac阻遏物的C末端四聚结构域,作为四链卷曲螺旋的模型系统(Fairman等,1995)。这些基于Lac的肽在b和c七肽的所有位置均包含谷氨酸(Lac21E)或赖氨酸(Lac21K),它们仅具有较弱的自缔合能力,但在混合时可提供高度稳定的异四聚体。这项研究代表了b和c heptad位置对卷曲线圈稳定性的重要性的第一个实验证据。最后,pH依赖性和NaCl依赖性研究表明,异四聚体的稳定性是由谷氨酸和赖氨酸之间的离子对相互作用驱动的。这些相互作用为每个潜在的谷氨酸-赖氨酸对贡献约0.6kcal / mol的稳定自由能。

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