The portal protein plays essential roles at different steps of the SPP1 DNA packaging process
The portal protein plays essential roles at different steps of the SPP1 DNA packaging process
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DOI：
10.1016/j.virol.2004.02.012
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发表时间：
2004-05-01
期刊：
影响因子：
3.7
通讯作者：
Tavares, P
中科院分区：
文献类型：
--
作者：
Isidro, A;Henriques, AO;Tavares, P
大量病毒使用专门的门户用于DNA进入病毒衣壳并在感染开始时用于其极化退出。这些病毒家族组装成二十面体的原衣壳，在其12个顶点之一含有门户蛋白寡聚体。病毒ATP酶（末端酶）与门顶相互作用，形成一个强大的分子马达，将DNA转移到原衣壳内部，以对抗陡峭的浓度梯度。门蛋白是这个DNA包装机器的重要组成部分。在门户蛋白gp6的噬菌体SPP1，阻止DNA包装的单个氨基酸取代的表征确定的包装机制，需要其行动的顺序步骤。Gp6在DNA包装的早期步骤和DNA易位到衣壳内部是必不可少的，它影响DNA包装的效率，它是决定包装的DNA分子大小的头部传感器的中心组分，并且对于头部完成蛋白封闭门孔以防止DNA易位的退出是必不可少的。在其一级结构中确定了每个步骤所需的gp6功能区域。门户寡聚体的结构之间的相似性和使用门户的病毒的DNA包装策略之间的相似性强烈表明，门户蛋白在大量病毒中起着相同的作用。(C)2004年爱思唯尔公司All rights reserved.
A large number of viruses use a specialized portal for entry of DNA to the viral capsid and for its polarized exit at the beginning of infection. These families of viruses assemble an icosahedral procapsid containing a portal protein oligomer in one of its 12 vertices. The viral ATPase (terminase) interacts with the portal vertex to form a powerful molecular motor that translocates DNA to the procapsid interior against a steep concentration gradient. The portal protein is an essential component of this DNA packaging machine. Characterization of single amino acid substitutions in the portal protein gp6 of bacteriophage SPP1 that block DNA packaging identified sequential steps in the packaging mechanism that require its action. Gp6 is essential at early steps of DNA packaging and for DNA translocation to the capsid interior, it affects the efficiency of DNA packaging, it is a central component of the headful sensor that determines the size of the packaged DNA molecule, and is essential for closure of the portal pore by the head completion proteins to prevent exit of the DNA encapsidated. Functional regions of gp6 necessary at each step are identified within its primary structure. The similarity between the architecture of portal oligomers and between the DNA packaging strategies of viruses using portals strongly suggests that the portal protein plays the same roles in a large number of viruses. (C) 2004 Elsevier Inc. All rights reserved.