Secondary structure of the mammalian 70-kilodalton heat shock cognate protein analyzed by circular dichroism spectroscopy and secondary structure prediction.
Secondary structure of the mammalian 70-kilodalton heat shock cognate protein analyzed by circular dichroism spectroscopy and secondary structure prediction.
复制标题
通过圆二色光谱和二级结构预测分析哺乳动物 70 千道尔顿热休克同源蛋白的二级结构。
DOI：
10.1021/bi00488a001
复制
发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Hightower,LE
中科院分区：
文献类型：
--
作者：
Sadis,S;Raghavendra,K;Hightower,LE
分子和细胞生物学系，康涅狄格大学，斯托尔斯，康涅狄格06269-3044 1990年5月31日接收; 1990年7月2日修订的Mandarin pt接收摘要：当细胞暴露于引起蛋白质损伤的应激剂时，热休克蛋白快速合成。70 kDa的热休克诱导的蛋白质和它们密切相关的组成型表达的同源蛋白结合未折叠和异常的多肽和亲水性肽。70 kDa的热休克蛋白，赋予与不同的多肽的能力的结构特征是未知的。在这项研究中，我们已经使用圆二色谱（CD）光谱和二级结构预测分析的哺乳动物70 kDa的热休克同源蛋白（HSC 70）的二级结构。hsc 70的远紫外CD光谱表明蛋白质中有很大一部分α-螺旋，与从α//3结构类蛋白质获得的光谱相似。用去卷积方法分析CD光谱得到二级结构含量的估计。结果表明，hsc 70内约有40%的α-螺旋和20%的非周期结构，在16 -41%/3-折叠和21-0%/3-转角之间。二级结构预测的Garnier-Osgu-thorpe-Robson方法应用于大鼠hsc 70氨基酸序列。α-螺旋和非周期性结构的预测估计值与CD分析得出的值密切匹配，而β-折叠和β-转角的预测估计值介于CD得出的值之间。目前的证据表明，70-kDa热休克蛋白的多肽配体结合结构域位于C-末端160个氨基酸内[Milarski，KL，& Morimoto，R. I.（1989）J. Cell Biol.109，1947-1962]。在hsc 70中，这一区域的大部分异常富含带电和极性氨基酸，并被预测具有高的a-螺旋含量。提出了基于这些结构特征的多肽结合模型。各种各样的环境扰动诱导细胞快速合成一组称为热休克（应激）蛋白的多肽[Lindquist和克雷格（1988）综述]。激活应激蛋白合成的多种处理共同具有引起变性或异常蛋白质的细胞内积累的潜力（Hightower，1980; Finley等人，1984; Ananthan等人，1986;爱丁顿等人，1989年）。真核细胞含有多基因家族，其编码几种密切相关且进化上保守的70-kDa应激蛋白（hsp 70家族），所述应激蛋白在其细胞内位置和调节方面不同（Pelham，
Department of Molecular and Cell Biology, The University of Connecticut, Storrs, Connecticut 06269-3044 Received May 31, 1990; Revised Manuscript Received July 2, 1990 abstract: Heat shock proteins are rapidly synthesized when cells are exposed to stressful agents that cause protein damage. The 70-kDa heat shock induced proteins and their closely related constitutively expressed cognate proteins bind to unfolded and aberrant polypeptides and to hydrophilic peptides. The structural features of the 70-kDa heat shock proteins that confer the ability to associate with diverse polypeptides are unknown. In this study, we have used circular dichroism (CD) spectroscopy and secondary structure prediction to analyze the secondary structure of the mammalian 70-kDa heat shock cognate protein (hsc 70). The far-ultraviolet CD spectrum of hsc 70 indicates a large fraction of a-helix in the protein and resembles the spectra one obtains from proteins of the a//3 structural class. Analysis of the CD spectra with deconvolution methods yielded estimates of secondary structure content. The results indicate about 40% a-helix and 20% aperiodic structure within hsc 70 and between16-41%/3-sheet and 21-0%/3-turn. The Garnier-Osgu-thorpe-Robson method of secondary structure prediction was applied to the rat hsc 70 amino acid sequence. The predicted estimates of a-helix and aperiodic structure closely matched the values derived from the CD analysis, whereas the predicted estimates of/3-sheet and/3-turn were midway between the CD-derived values. Present evidence suggests that the polypeptide ligand binding domain of the 70-kDa heat shock protein resides within the C-terminal 160 amino acids [Milarski, KL, & Morimoto, R. I.(1989) J. Cell Biol. 109, 1947-1962]. Much of this region in hsc 70 is unusually rich in charged and polar amino acids and is predicted to have a high a-helical content. A model for polypeptide binding based on these structural features is proposed. wide variety of environmental perturbations induce cells to rapidly synthesize a group of polypeptides known as the heat shock (stress) proteins [reviewed by Lindquist and Craig (1988)]. The diverse treatments that activate stress protein synthesis have in common the potential to cause the intracellular accumulation of denatured or aberrant protein (Hightower, 1980; Finley et al., 1984; Ananthan et al., 1986; Edington et al., 1989). Eukaryotic cells contain a multigene family that encodes several closely related and evolutionarily conserved 70-kDa'stress proteins (the hsp 70 family) that differ in their intracellular location and regulation (Pelham,