Cenatiempo Y
Biochimie. 1986 Apr;68(4):505-15. doi: 10.1016/s0300-9084(86)80195-x.
Transcription-translation coupled systems have been developed to study prokaryotic gene expression. Several types of expression system have been described. The original system consists of a crude unfractionated Escherichia coli extract, which supports protein synthesis directed by a template DNA. Control of gene expression at the transcriptional stage has been studied using this unfractionated system. In this respect, two examples of particular interest, lactose and tryptophan operons, are described. Other systems are either partially reconstituted or highly defined, containing up to 30 purified factors necessary for transcription (RNA polymerase) and translation (aminoacyl-tRNA synthetases, initiation, elongation and release factors). Additional differences between the various systems relate to the analysis of the gene products. Whereas most methods involve analysis of the totally synthesized protein, a particular system implies the formation of only the N-terminal di- or tripeptide of the gene product. Reconstituted systems have proved useful in studies on transcriptional, e.g., discovery and role of L factor, as well as translational regulation of gene expression, e.g., autogenous control of ribosomal protein synthesis.
转录-翻译偶联系统已被开发用于研究原核基因表达。已描述了几种类型的表达系统。最初的系统由未分级的大肠杆菌粗提物组成，它支持由模板DNA指导的蛋白质合成。使用这种未分级的系统研究了转录阶段的基因表达调控。在这方面，描述了两个特别有趣的例子，即乳糖操纵子和色氨酸操纵子。其他系统要么是部分重组的，要么是高度明确的，包含多达30种转录（RNA聚合酶）和翻译（氨酰-tRNA合成酶、起始、延伸和释放因子）所需的纯化因子。各种系统之间的其他差异与基因产物的分析有关。虽然大多数方法涉及对完全合成的蛋白质的分析，但一种特定的系统意味着仅形成基因产物的N端二肽或三肽。重组系统已被证明在转录研究中很有用，例如L因子的发现和作用，以及基因表达的翻译调控，例如核糖体蛋白合成的自体调控。
