Smagowicz W J, Scheit K H
Nucleic Acids Res. 1978 Jun;5(6):1919-32. doi: 10.1093/nar/5.6.1919.
Ternary complexes of T7 DNA, RNA polymerase and the antibiotic rifampicin carry out the promoter specific abortive initiation when dinucleoside monophosphates were employed as primers. Primed abortive initiation, leading to synthesis of trinucleoside diphosphates, only occured with combinations of primers and substrates complementary to a promoter region of 8 base pairs centered around the origin of transcription. The steady state kinetics of three abortive initiations at T7 promoter A3 were studied in detail. The reactions appeared to be truly ordered. Affinity constants, maximal velocities and elementary step rate constants were thus obtained. The stimulation by dinucleoside monophosphate primers is brought about by positively effecting the function of the substrate site rather then by their higher affinity to the primer site of the transcriptional complex.
当使用二核苷单磷酸作为引物时,T7 DNA、RNA 聚合酶和抗生素利福平的三元复合物进行启动子特异性流产起始。引物介导的流产起始导致三核苷二磷酸的合成,仅在引物和底物与以转录起始点为中心的8个碱基对的启动子区域互补的组合中发生。详细研究了T7启动子A3处三次流产起始的稳态动力学。反应似乎是真正有序的。由此获得了亲和常数、最大速度和基本步骤速率常数。二核苷单磷酸引物的刺激是通过积极影响底物位点的功能,而不是通过它们对转录复合物引物位点的更高亲和力实现的。