Filamentous Bacteriophage Pf1 Has 27 Subunits in Its Axial Repeat
Filamentous Bacteriophage Pf1 Has 27 Subunits in Its Axial Repeat
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丝状噬菌体 Pf1 的轴向重复有 27 个亚基
DOI：
10.1101/087969122.8.627
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
D. Caspar
中科院分区：
文献类型：
--
作者：
L. Makowski;D. Caspar
分子模型的建立现在被应用于分析丝状噬菌体外壳蛋白的结构（Marvin and Wachtel 1975 Marvin and Wachtel 1976），其利用来自低分辨率纤维衍射和氨基酸序列的信息，而不求助于常规的蛋白质晶体学方法。这种方法对于研究结构蛋白的结构具有重要意义，这些结构蛋白以自己有目的的方式聚集，以构建对称的细丝，壳或片，而不是适合高分辨率衍射分析的晶体。Pf 1噬菌体结构的一般情况（Marvin et al. 1974 a; Marvin and Wachtel 1975; Nakashima et al. 1975）是46个残基的蛋白质亚基主要是α -螺旋的;亚基以规则的重叠螺旋排列互锁，形成直径约60 A、壁厚约20 A的蛋白质管。该螺旋管包含两条延伸的环状DNA分子链;亚基的带正电荷的C末端位于管内靠近DNA的位置，而酸性的N末端位于外表面。Marvin和Wachtel（1976）通过将α -螺旋亚基以规则螺旋装配的方式互锁，构建了Pf 1蛋白外壳的详细分子模型。该模型假定沿着颗粒的轴每沿着3.4 A有一个亚基;即，4.4在15-A螺距螺旋的每圈中有22个亚基或在75-A螺旋重复周期中有22个亚基。(The重复周期略有不同的湿度变化，从约72 A的完全干燥…
Molecular model building is now being applied to analyze the structure of the filamentous phage coat protein (Marvin and Wachtel 1975Marvin and Wachtel 1976) by using information from low-resolution fiber diffraction and amino acid sequence without recourse to conventional methods of protein crystallography. This approach has important implications for the study of the structure of structural proteins that aggregate in their own purposeful way to build symmetric filaments, shells, or sheets rather than crystals suitable for high-resolution diffraction analysis. The general picture of the Pf1 phage structure (Marvin et al. 1974a; Marvin and Wachtel 1975; Nakashima et al. 1975) is that the 46-residue protein subunit is largely α -helical; the subunits are interlocked in a regular, overlapping spiral arrangement to form a protein tube about 60 A in diameter with a wall about 20 A thick. This helical tube contains the two strands of the extended circular DNA molecule; the positively charged C-terminal end of the subunit is at the inside of the tube near the DNA and the acidic N terminus is at the outside surface. Marvin and Wachtel (1976) have constructed a detailed molecular model of the Pf1 protein coat by interlocking α -helical subunits in a regular helical assembly. This model presumes that there is one subunit every 3.4 A along the axis of the particle; i.e., 4.4 subunits per turn of the 15-A pitch helix or 22 subunits in the 75-A helix repeat period. (The repeat period varies slightly with changes in humidity, from about 72 A for completely dry...