Markovtsov V, Mustaev A, Goldfarb A
The Public Health Research Institute, New York, NY 10016, USA.
Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3221-6. doi: 10.1073/pnas.93.8.3221.
By using a crosslinkable probe incorporated into the 3' terminus of nascent transcript, three sites were mapped in Escherichia coli RNA polymerase that are contacted by the RNA in the productive elongation complex. Two of these sites are in the beta subunit and one is in the beta' subunit. During elongation, the transcription complex occasionally undergoes an arrest whereby it can neither extend nor release the RNA transcript. It is demonstrated that in an arrested complex, the three contacts of RNA 3' terminus are lost, while a new beta' subunit contact becomes prominent. Thus, elongation arrest appears to involve the disengagement of the bulk of the active center from the 3' terminus of RNA and the transfer of the terminus into a new protein environment.
通过使用掺入新生转录本3'末端的可交联探针，在大肠杆菌RNA聚合酶中定位了三个与延伸复合物中RNA接触的位点。其中两个位点在β亚基中，一个位点在β'亚基中。在延伸过程中，转录复合物偶尔会发生停滞，在此期间它既不能延伸也不能释放RNA转录本。结果表明，在停滞的复合物中，RNA 3'末端的三个接触点消失，而一个新的β'亚基接触点变得突出。因此，延伸停滞似乎涉及活性中心的大部分与RNA 3'末端的脱离以及末端转移到新的蛋白质环境中。
