Refined structure of lac repressor headpiece (1-56) determined by relaxation matrix calculations from 2D and 3D NOE data: change of tertiary structure upon binding to the lac operator.
Refined structure of lac repressor headpiece (1-56) determined by relaxation matrix calculations from 2D and 3D NOE data: change of tertiary structure upon binding to the lac operator.
复制标题
通过 2D 和 3D NOE 数据的松弛矩阵计算确定 lac 阻遏物头件 (1-56) 的精细结构：与 lac 操纵子结合后三级结构的变化。
DOI：
10.1006/jmbi.1996.0356
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发表时间：
1996
影响因子：
5.6
通讯作者：
R. Kaptein
中科院分区：
文献类型：
--
作者：
Monique Slijper;A. Bonvin;R. Boelens;R. Kaptein
利用二维和三维核磁共振波谱数据对lac阻遏物（头饰1-56；HP56）的DNA结合域的溶液结构进行了细化。该结构来源于1546个约束（平均每个残基27.6个），包括389个残基内约束，402个连续约束，385个中程约束和325个远程约束，以及30个phi和15 chi 1二面角约束。结构的确定是通过直接细化的方法，对核Overhauser增强峰体积与程序恐龙。最终选出的32个结构的均方根偏差为0.43（+/-0.08）埃（主链）和0.95（+/-0.08）埃（所有重原子）的最佳确定区域（残基3至49）。集合r因子为0.35，与实验数据吻合较好。该结构显示出良好的立体化学性质。比较了游离型和DNA络合型紫胶抑制子头的核磁共振构象。两种构象的二级构造元素组成区域具有密切的对应关系。然而，螺旋II和III之间的环的构象在头饰的络合上发生了相当大的变化。lac HP56环构象的这种变化对于将残基Asn25和His29的侧链结合到lac操作子DNA上是必不可少的。最后，对突变不耐受的紫胶头残基进行了分析。这些突变敏感残基中的大多数对于头套区域的正确折叠是重要的，并且这些残基中的许多也涉及与操作员DNA的接触。
The solution structure of the DNA binding domain of lac repressor (headpiece 1-56; HP56) has been refined using data from 2D and 3D NMR spectroscopy. The structure was derived from 1546 restraints (giving an average of 27.6 per residue), comprising 389 intraresidual, 402 sequential, 385 medium range and 325 long range distance restraints and also 30 phi and 15 chi 1 dihedral angle restraints. The structures were determined by the method of direct refinement against nuclear Overhauser enhancement peak volumes with the program DINOSAUR. The final set of 32 selected structures displayed an r.m.s. deviation from the average of 0.43(+/-0.08) A angstroms (backbone) and 0.95(+/-0.08) angstroms (all heavy atoms) for the best defined region of the protein (residues 3 to 49). The ensemble R-factor was 0.35, which indicates close correspondence with the experimental data. The structures revealed good stereochemical qualities. The conformations of the NMR structures of free and DNA complexed lac repressor headpiece were compared. The regions comprising the secondary structure elements show close correspondence for both conformations. However, the conformation of the loop between helix II and III changes considerably upon complexation of the headpiece. This change in the conformation of the loop in lac HP56 is essential for binding of the side-chains of residues Asn25 and His29 to the lac operator DNA. Finally, the lac headpiece residues that are intolerant to mutations were analysed. Most of these mutation-sensitive residues are important for a correct folding of the headpiece region, and a number of these residues are also involved in contacting the operator DNA.