Packing of coat protein amphipathic and transmembrane helices in filamentous bacteriophage M13: role of small residues in protein oligomerization.
Packing of coat protein amphipathic and transmembrane helices in filamentous bacteriophage M13: role of small residues in protein oligomerization.
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丝状噬菌体 M13 中外壳蛋白两亲性和跨膜螺旋的包装：小残基在蛋白质寡聚化中的作用。
DOI：
10.1006/jmbi.1995.0469
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发表时间：
1995
影响因子：
5.6
通讯作者：
C. Deber
中科院分区：
文献类型：
--
作者：
K. Williams;M. Glibowicka;Zuomei Li;Hong Li;Amir R. Khan;Yv Chen;Jing Wang;D. Marvin;C. Deber
丝状菌噬菌体M13是一种重要的克隆和噬菌体展示载体，其主要外壳蛋白（基因8）由约2700个拷贝的50个残基包裹。这种蛋白质以膜蛋白的形式存在，同时稳定地插入其E。大肠杆菌宿主内膜，并在组装和包装到无脂质病毒粒子中的噬菌体DNA上时作为外壳蛋白。为了研究这些过程背后的特定蛋白质-蛋白质相互作用，我们使用了整个基因8的随机和饱和诱变的组合来评估每个位置对突变的敏感性。在约100个活的M13突变体的所得文库中，发现构成N-末端两亲性螺旋片段的非极性面和疏水性（有效跨膜）螺旋片段的面的“小”残基（Ala、Gly、Ser）是高度保守的。这些结果支持了一种模型，其中外壳蛋白包装是稳定的存在下，每个蛋白质亚基内的两个“寡聚化片段”，即特定的螺旋区域，具有丰富的小残基的功能，以促进接近的α-螺旋面。
Filamentous bacteriophage M13, an important cloning and phage display vector, is encapsulated by ca 2700 copies of its 50-residue major coat protein (gene 8). This protein occurs as a membrane protein while stably inserted into its E. coli host inner membrane, and as a coat protein upon assembly and packing onto phage DNA in the lipid-free virion. To examine the specific protein-protein interactions underlying these processes, we used a combination of randomized and saturation mutagenesis of the entire gene 8 to assess the susceptibility of each position to mutation. In the resulting library of ca 100 viable M13 mutants, "small" residues (Ala,Gly,Ser), which constitute the non-polar face of the N-terminal amphipathic helical segment, and a face of the hydrophobic (effective transmembrane) helical segment, were found to be highly conserved. These results support a model in which coat protein packing is stabilized by the presence within each protein subunit of two "oligomerization segments", i.e. specific helical regions with faces rich in small residues which function to promote the close approach of alpha-helices.