Crute J J, LaDuca R J, Johanson K O, McHenry C S, Bambara R A
J Biol Chem. 1983 Sep 25;258(18):11344-9.
We have previously shown that the processive synthesis of long DNA products on a poly(dA) X oligo(dT)10 primer-template is facilitated by formation of an isolable initiation complex between the Escherichia coli DNA polymerase III holoenzyme and DNA in the presence of ATP (Fay, P. J., Johanson, K. O., McHenry, C. S., and Bambara, R. A. (1982) J. Biol. Chem. 257, 5692-5699). Here we have demonstrated that the ATP requirement for processive synthesis can be obviated by a large excess of the beta subunit of the DNA polymerase III holoenzyme. The reaction which occurs in the presence of excess beta can be distinguished from the ATP-mediated reaction by its salt sensitivity and the lack of stabile initiation complex formation between polymerase and primed DNA. A model is presented which suggest that one of the functions of ATP in the DNA polymerase III holoenzyme reaction is to lock beta into the replicative complex such that it does not readily equilibrate with solution.
我们之前已经表明，在ATP存在的情况下，大肠杆菌DNA聚合酶III全酶与DNA之间形成可分离的起始复合物，有助于在聚（dA）X寡聚（dT）10引物模板上进行长DNA产物的连续合成（Fay, P. J., Johanson, K. O., McHenry, C. S., and Bambara, R. A. (1982) J. Biol. Chem. 257, 5692 - 5699）。在此我们证明，DNA聚合酶III全酶的β亚基大量过量可消除连续合成对ATP的需求。在过量β亚基存在下发生的反应，可通过其对盐的敏感性以及聚合酶与引发的DNA之间缺乏稳定起始复合物形成，与ATP介导的反应区分开来。提出了一个模型，该模型表明ATP在DNA聚合酶III全酶反应中的功能之一是将β亚基锁定在复制复合物中，使其不易与溶液达到平衡。
