Debyser Z, Tabor S, Richardson C C
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Cell. 1994 Apr 8;77(1):157-66. doi: 10.1016/0092-8674(94)90243-7.
We have used the T7 DNA replication system to examine coordination of leading and lagging strand synthesis at a replication fork. The 63 kd gene 4 protein provides both helicase and primase activities; we demonstrate that primer synthesis inhibits helicase activity on a synthetic replication fork. Lagging strand DNA synthesis by a complex of gene 4 protein and T7 DNA polymerase decreases the rate of leading strand synthesis. Both leading and lagging strand synthesis are resistant to dilution of the replication proteins, and to challenge with heparin. Furthermore, dilution does not increase the average length of Okazaki fragments. We propose that leading and lagging strand synthesis at a T7 replication fork are coupled and that the replication proteins are recycled.
我们利用T7 DNA复制系统来研究复制叉处前导链和后随链合成的协调性。63 kd的基因4蛋白兼具解旋酶和引发酶活性；我们证明，在合成复制叉上，引物合成会抑制解旋酶活性。由基因4蛋白和T7 DNA聚合酶组成的复合物进行的后随链DNA合成会降低前导链合成的速率。前导链和后随链的合成对复制蛋白的稀释以及肝素的挑战均具有抗性。此外，稀释并不会增加冈崎片段的平均长度。我们提出，T7复制叉处的前导链和后随链合成是偶联的，并且复制蛋白会循环利用。
