Department of Microbiology, Third Military Medical University, Chongqing, China.
Arch Virol. 2012 Nov;157(11):2133-41. doi: 10.1007/s00705-012-1409-5. Epub 2012 Jul 22.
Terminase proteins are responsible for DNA recognition and initiation of DNA packaging in phages. We previously reported the genomic sequence of a temperate Pseudomonas aeruginosa phage, PaP3, and determined its precise integration site in the host bacterial chromosome. In this study, we present a detailed functional identification of the DNA packaging terminase for phage PaP3. The purified large subunit p03 was demonstrated to possess ATPase and nuclease activities, as well as the ability to bind to specific DNA when it is unassembled. In addition, a small terminase subunit (p01) of a new type was found and shown to bind specifically to cos-containing DNA and stimulate the cos-cleavage and ATPase activities of p03. The results presented here suggest that PaP3 utilizes a typical cos site mechanism for DNA packaging and provide a first step towards understanding the molecular mechanism of the PaP3 DNA packaging reaction.
噬菌体的终止酶蛋白负责 DNA 的识别和包装起始。我们之前报道了一株温和型铜绿假单胞菌噬菌体 PaP3 的基因组序列，并确定了其在宿主细菌染色体上的精确整合位点。在这项研究中，我们详细鉴定了噬菌体 PaP3 的 DNA 包装终止酶的功能。纯化的大分子量亚基 p03 被证实具有 ATP 酶和核酸酶活性，并且在未组装时能够与特定的 DNA 结合。此外，还发现了一种新型的小终止酶亚基（p01），它能够特异性地结合含有 cos 的 DNA，并刺激 p03 的 cos 切割和 ATP 酶活性。这里呈现的结果表明，PaP3 利用了一种典型的 cos 位点机制进行 DNA 包装，并为理解 PaP3 DNA 包装反应的分子机制提供了第一步的认识。
