Kim S, Dallmann H G, McHenry C S, Marians K J
Graduate Program in Molecular Biology, Cornell University Graduate School of Medical Sciences, New York 10021, USA.
Cell. 1996 Feb 23;84(4):643-50. doi: 10.1016/s0092-8674(00)81039-9.
The E. coli replication fork synthesizes DNA at the rate of nearly 1000 nt/s. We show here that an interaction between the tau subunit of the replicative polymerase (the DNA polymerase III holoenzyme) and the replication fork DNA helicase (DnaB) is required to mediate this high rate of replication fork movement. In the absence of this interaction, the polymerase follows behind the helicase at a rate equal to the slow (approximately 35 nt/s) unwinding rate of the helicase alone, whereas upon establishing a tau-DnaB contact, DnaB becomes a more effective helicase, increasing its translocation rate by more than 10-fold. This finding establishes the existence of both a physical and communications link between the two major replication machines in the replisome: the DNA polymerase and the primosome.
大肠杆菌复制叉以近1000个核苷酸/秒的速度合成DNA。我们在此表明，复制性聚合酶（DNA聚合酶III全酶）的τ亚基与复制叉DNA解旋酶（DnaB）之间的相互作用是介导这种高速度复制叉移动所必需的。在没有这种相互作用的情况下，聚合酶以与解旋酶单独的缓慢（约35个核苷酸/秒）解旋速度相等的速率跟在解旋酶后面，而一旦建立了τ-DnaB接触，DnaB就会成为更有效的解旋酶，其移位速率提高10倍以上。这一发现证实了复制体中两个主要复制机器之间存在物理和通信联系：DNA聚合酶和引发体。
