DNA的復(fù)制和轉(zhuǎn)錄通常在體內(nèi)同時發(fā)生。在DNA鏈上用于進行DNA復(fù)制的DNA合成酶與用于轉(zhuǎn)錄的RNA合成酶迎頭碰撞會使DNA合成過程停止,，但一個復(fù)制體（replisome）碰到一個在DNA模板上沿同一方向工作的一個RNA聚合酶會發(fā)生什么情況呢,？
美國洛克菲勒大學的Richard Pomerantz 和 Mike O’Donnell發(fā)現(xiàn),，復(fù)制體（一種集聚合與校對活性于一身的多酶復(fù)合物）碰到障礙時可以靈活完成自己的任務(wù)。RNA聚合酶被從DNA中移走，但復(fù)制體和新生成的mRNA仍然附著在其上,。一個復(fù)制組裝因子（beta clamp）會找到mRNA的3\'端,，并與仍然結(jié)合在一起的復(fù)制體相連，后者利用mRNA作為一個引子來重新啟動DNA的合成,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 456, 762-766 (11 December 2008) | doi:10.1038/nature07527
The replisome uses mRNA as a primer after colliding with RNA polymerase
Richard T. Pomerantz1 & Mike O'Donnell1
The Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, New York 10021, USA
Replication forks are impeded by DNA damage and protein–nucleic acid complexes such as transcribing RNA polymerase. For example, head-on collision of the replisome with RNA polymerase results in replication fork arrest. However, co-directional collision of the replisome with RNA polymerase has little or no effect on fork progression. Here we examine co-directional collisions between a replisome and RNA polymerase in vitro. We show that the Escherichia coli replisome uses the RNA transcript as a primer to continue leading-strand synthesis after the collision with RNA polymerase that is displaced from the DNA. This action results in a discontinuity in the leading strand, yet the replisome remains intact and bound to DNA during the entire process. These findings underscore the notable plasticity by which the replisome operates to circumvent obstacles in its path and may explain why the leading strand is synthesized discontinuously in vivo.
