Yean D, Gralla J
Department of Chemistry and Biochemistry, University of California at Los Angeles 90095-1569, USA.
Nucleic Acids Res. 1996 Jul 15;24(14):2723-9. doi: 10.1093/nar/24.14.2723.
Basal and GC-box activated transcription were compared by various assays in order to learn the basis for an 8-fold difference observed under standard conditions. The time required for forming pre-initiation complexes and initiating and elongating RNA synthesis, and the extent of transcription reinitiation were found to be quite similar for basal and activated transcription, with complex formation being the slow step in both cases. The extent of activation was found to vary widely with the amount of template DNA used. Activated pre-initiation complexes were found to have a higher stability than basal complexes. The data are interpreted to indicate that GC-box elements do not stimulate the rate constants for critical steps in this system but rather increase the equilibrium constant for pre-initiation complex formation, probably by 10-30-fold.
通过各种测定方法比较了基础转录和GC框激活的转录，以便了解在标准条件下观察到的8倍差异的基础。发现形成预起始复合物、起始和延伸RNA合成所需的时间，以及转录重新起始的程度，对于基础转录和激活转录来说非常相似，复合物形成在两种情况下都是较慢的步骤。发现激活程度随所用模板DNA的量有很大差异。发现激活的预起始复合物比基础复合物具有更高的稳定性。这些数据被解释为表明GC框元件不会刺激该系统中关键步骤的速率常数，而是可能将预起始复合物形成的平衡常数提高10至30倍。
