Blanco L, Bernad A, Lázaro J M, Martín G, Garmendia C, Salas M
Centro de Biología Molecular (Consejo Superior de Investigaciones Científicas), Universidad Autónoma de Madrid, Spain.
J Biol Chem. 1989 May 25;264(15):8935-40.
The results presented in this paper indicate that the phi 29 DNA polymerase is the only enzyme required for efficient synthesis of full length phi 29 DNA with the phi 29 terminal protein, the initiation primer, as the only additional protein requirement. Analysis of phi 29 DNA polymerase activity in various in vitro DNA replication systems indicates that two main reasons are responsible for the efficiency of this minimal system: 1) the phi 29 DNA polymerase is highly processive in the absence of any accessory protein; 2) the polymerase itself is able to produce strand displacement coupled to the polymerization process. Using primed M13 DNA as template, the phi 29 DNA polymerase is able to synthesize DNA chains greater than 70 kilobase pairs. Furthermore, conditions that increase the stability of secondary structure in the template do not affect the processivity and strand displacement ability of the enzyme. Thus, the catalytic properties of the phi 29 DNA polymerase are appropriate for a phi 29 DNA replication mechanism involving two replication origins, strand displacement and continuous synthesis of both strands. The enzymology of phi 29 DNA replication would support a symmetrical model of DNA replication.
本文给出的结果表明，phi 29 DNA聚合酶是使用phi 29末端蛋白（起始引物）作为唯一额外蛋白质需求来高效合成全长phi 29 DNA所需的唯一酶。对各种体外DNA复制系统中phi 29 DNA聚合酶活性的分析表明，这个最小系统效率高主要有两个原因：1）phi 29 DNA聚合酶在没有任何辅助蛋白的情况下具有高度的持续性；2）该聚合酶本身能够产生与聚合过程偶联的链置换。以引发的M13 DNA为模板，phi 29 DNA聚合酶能够合成大于70千碱基对的DNA链。此外，增加模板二级结构稳定性的条件不会影响该酶的持续性和链置换能力。因此，phi 29 DNA聚合酶的催化特性适用于涉及两个复制起点、链置换以及两条链连续合成的phi 29 DNA复制机制。phi 29 DNA复制的酶学将支持DNA复制的对称模型。
