Strategies for selecting mutation sites for methionine enhancement in the bean seed storage protein phaseolin.
Strategies for selecting mutation sites for methionine enhancement in the bean seed storage protein phaseolin.
复制标题
选择豆种子储存蛋白菜豆蛋白中蛋氨酸增强的突变位点的策略。
DOI：
10.1007/bf01025119
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Murai,N
中科院分区：
文献类型：
--
作者：
Dyer,JM;Nelson,JW;Murai,N
利用分子力学计算方法，从α-碳坐标系出发，生成了菜豆蛋白的完整三维结构。该结构被用作模板来模拟旨在增加菜豆蛋白的甲硫氨酸含量的修饰。设计了亲水性、富含甲硫氨酸的环状插入序列。模拟诱变表明，插入片段可能被容纳在蛋白质的环区和环区，但不在α-螺旋内。在菜豆蛋白的中心核心β-桶中用甲硫氨酸替换疏水性氨基酸也增加了甲硫氨酸含量。计算表明，甲硫氨酸可以有效地取代保守或变异的亮氨酸，异亮氨酸和缬氨酸残基。然而，丙氨酸残基对取代更敏感，并且在甲硫氨酸取代的影响中表现出高变异性。在桶内部引入多个取代表明，取代的残基可以有利地相互作用，以减轻由单个取代引起的局部扰动。分子动力学模拟也被用来研究菜豆蛋白的结构组织。计算结果表明，菜豆蛋白的主要结构域之间存在广泛的堆积相互作用，这对蛋白质的折叠和稳定性具有重要意义。由于所提出的突变蛋白质可以生产和研究，这里提出的结果提供了一个理想的测试，以确定是否有通过计算机模拟获得的效果和体内表达的蛋白质结构上的突变的影响之间的相关性。
The complete three-dimensional structure of the bean seed storage protein phaseolin was generated from α-carbon coordinates by using molecular mechanic calculations. This structure was used as a template to simulate modifications aimed at increasing the methionine content of phaseolin. A hydrophilic, methionine-rich looping insert sequence was designed. Simulated mutagenesis shows that the insert might be accommodated in turn and loop regions of the protein, but not within an α-helix. Methionine content was also increased by the replacement of hydrophobic amino acids with methionine in the central core β-barrels of the phaseolin protein. Calculations indicated that methionine can effectively replace conserved or variant leucine, isolecuine, and valine residues. However, alanine residues were much more sensitive to substitution, and demonstrated high variability in the effects of methionine replacement. Introduction of multiple substitutions in the barrel interior demonstrated that the replaced residues could interact favorably to relieve local perturbations caused by individual substitutions. Molecular dynamics simulations were also utilized to study the structural organization of phaseolin. The calculations indicate that there are extensive packing interactions between the major domains of phaseolin, which have important implications for protein folding and stability. Since the proposed mutant proteins can be produced and studied, the results presented here provide an ideal test to determine if there is a correlation between the effects obtained by computer simulation and the effects of the mutations on the protein structure expressedin vivo.