Caldentey J, Blanco L, Bamford D H, Salas M
Department of Genetics, University of Helsinki, Finland.
Nucleic Acids Res. 1993 Aug 11;21(16):3725-30. doi: 10.1093/nar/21.16.3725.
Bacteriophage PRD1 replicates its DNA by means of a protein-primed replication mechanism. Using single-stranded oligonucleotide templates carrying the sequence corresponding to the 25 first bases of the 3' end of PRD1 DNA, and Mg2+ as the activating metal ion of the phage DNA polymerase, we show that the fourth base from the 3' end of the template directs, by base complementarity, the dNMP to be linked to the phage terminal protein (TP) in the initiation reaction. This result suggests that phage PRD1 maintains its 3' end DNA sequences via a sliding-back mechanism. The single-stranded DNA templates could not be replicated by the PRD1 DNA polymerase, much in contrast to the natural TP-DNA. Nevertheless, the analysis of the transition products obtained with TP-DNA and origin-containing oligonucleotides suggests that sliding-back occurs stepwise, the fourth base being the directing position during the entire process.
噬菌体PRD1通过蛋白质引发的复制机制复制其DNA。使用携带与PRD1 DNA 3'端前25个碱基序列相对应的单链寡核苷酸模板，并以Mg2+作为噬菌体DNA聚合酶的激活金属离子，我们发现模板3'端的第四个碱基通过碱基互补性在起始反应中指导dNMP与噬菌体末端蛋白（TP）相连。这一结果表明噬菌体PRD1通过回滑机制维持其3'端DNA序列。与天然的TP-DNA形成鲜明对比的是，PRD1 DNA聚合酶无法复制单链DNA模板。然而，对用TP-DNA和含起始位点的寡核苷酸获得的过渡产物的分析表明，回滑是逐步发生的，第四个碱基在整个过程中是指导位置。
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