López de Saro Francisco, Georgescu Roxana E, Leu Frank, O'Donnell Mike
The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Philos Trans R Soc Lond B Biol Sci. 2004 Jan 29;359(1441):25-30. doi: 10.1098/rstb.2003.1361.
The sliding clamps of chromosomal replicases are acted upon by both the clamp loader and DNA polymerase. Several other proteins and polymerases also interact with the clamp. These proteins bind the clamp at the same spot and use it in sequential fashion. First the clamp loader must bind the clamp in order to load it onto DNA, but directly thereafter the clamp loader must clear away from the clamp so it can be used by the replicative DNA polymerase. At the end of replication, the replicase is ejected from the clamp, which presumably allows the clamp to interact with yet other proteins after its use by the replicase. This paper describes how different proteins in the Escherichia coli replicase, DNA polymerase III holoenzyme, coordinate their traffic flow on the clamp. The mechanism by which traffic flow on the beta clamp is directed is based on competition of the proteins for the clamp, where DNA structure modulates the competition. It seems likely that the principles will generalize to a traffic flow of other factors on these circular clamp proteins.
染色体复制酶的滑动夹受到夹装载器和DNA聚合酶的作用。其他几种蛋白质和聚合酶也与夹子相互作用。这些蛋白质在同一位置结合夹子并依次使用它。首先，夹装载器必须结合夹子以便将其装载到DNA上，但紧接着夹装载器必须从夹子上离开，这样它才能被复制性DNA聚合酶使用。在复制结束时，复制酶从夹子上被弹出，这大概使得夹子在被复制酶使用后能够与其他蛋白质相互作用。本文描述了大肠杆菌复制酶DNA聚合酶III全酶中的不同蛋白质如何在夹子上协调它们的运输流程。β夹上运输流程的导向机制基于蛋白质对夹子的竞争，其中DNA结构调节这种竞争。这些原则似乎有可能推广到这些环状夹蛋白上其他因子的运输流程。
