The lac repressor protein: molecular shape, subunit structure, and proposed model for operator interaction based on structural studies of microcrystals.
The lac repressor protein: molecular shape, subunit structure, and proposed model for operator interaction based on structural studies of microcrystals.
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紫胶阻遏蛋白：分子形状、亚基结构以及基于微晶结构研究的操作者相互作用模型。
DOI：
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发表时间：
1974
影响因子：
11.1
通讯作者：
D. Engelman
中科院分区：
文献类型：
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作者：
T. Steitz;T. Richmond;D. Wise;D. Engelman
电子显微镜和粉末X-射线衍射研究小晶体的乳糖阻遏蛋白提供了证据，其分子形状和亚基结构，这反过来又表明了一种可能的模式的阻遏-运营商的相互作用。晶体属正交晶系，空间群为P222（1），晶胞参数为a = 140，B = 91，c = 117。这种四聚体蛋白质看起来相当不对称，具有大约140 A × 60 A × 45 A的分子尺寸。在电子显微照片中观察到的投影分子轮廓的哑铃形状可以通过假设亚基通过222对称性相关并且被放置在平面矩形的角上来解释。我们提出了一个模型的阻遏物-运营商的相互作用，其中的DNA结合到阻遏物与其长轴对齐的阻遏物，其2倍轴重合的阻遏物的两倍轴。
Electron microscopic and powder x-ray diffraction studies of small crystals of the lac repressor protein provide evidence on its molecular shape and subunit structure which in turn suggests a possible mode of repressor-operator interaction. The crystals are probably orthorhombic space group P222(1) with unit cell dimensions of a = 140, b = 91, c = 117 A. This tetrameric protein appears rather asymmetric, having approximate molecular dimensions of 140 A by 60 A by 45 A. The dumbbell shape of the projected molecular outline observed in the electron micrographs can be explained by assuming that the subunits are related by 222 symmetry and are placed at the corners of a plane rectangle. We propose a model for repressor-operator interaction in which the DNA binds to the repressor with its long axis aligned with that of the repressor and with its 2-fold axis coincident with a twofold axis of the repressor.