Buhot Laurence, Horvàth Eva, Medgyesy Peter, Lerbs-Mache Silva
Laboratoire Plastes et Differenciation cellulaire, Université Joseph Fourier and Centre National de la Recherche Scientifique, BP 53, F-38041 Grenoble, France.
Plant J. 2006 May;46(4):700-7. doi: 10.1111/j.1365-313X.2006.02718.x.
Plastid transformation technologies have developed rapidly over the last few years, reflecting their value in the study of the principal mechanisms of plastid gene expression and commercial interest in using plastids as bioreactors. Application of this technology is still limited by the difficulty of obtaining regulated, selective expression of plastid transgenes. The plastid genome is transcribed by two different types of RNA polymerase. One of them is of the eubacterial type of polymerase, and its subunits are encoded in the plastid genome [plastid-encoded RNA polymerase (PEP)]. The other one is of the phage type and nucleus-encoded [nucleus-encoded RNA polymerase (NEP)]. To obtain selective transgene expression, we have made use of the similarities and differences between the eubacterial and the plastid eubacterial type transcription systems. We created a hybrid transcription system in which the transgene is placed under the control of a eubacterial promoter which does not exist in the plastid genome and which is not recognized by the plastid endogenous transcriptional machinery. Selective transcription of the transgene is achieved by the supply of a chimeric transcription factor that interacts with PEP and directs it specifically to the foreign eubacterial-type transgene promoter. This hybrid transcription system could be used for biotechnological and fundamental research applications as well as in the characterization of the evolutionary differences between the eubacterial and the plastid eubacterial-type transcription systems.
在过去几年中，质体转化技术发展迅速，这反映出其在质体基因表达主要机制研究中的价值以及将质体用作生物反应器的商业价值。然而，由于难以实现质体转基因的调控性、选择性表达，该技术的应用仍受到限制。质体基因组由两种不同类型的RNA聚合酶转录。其中一种是细菌类型的聚合酶，其亚基由质体基因组编码[质体编码的RNA聚合酶（PEP）]。另一种是噬菌体类型且由细胞核编码的[细胞核编码的RNA聚合酶（NEP）]。为了实现转基因的选择性表达，我们利用了细菌和质体细菌型转录系统之间的异同。我们创建了一种杂交转录系统，其中转基因置于质体基因组中不存在且不被质体内源转录机制识别的细菌启动子的控制之下。通过提供一种与PEP相互作用并将其特异性导向外源细菌型转基因启动子的嵌合转录因子，实现转基因的选择性转录。这种杂交转录系统可用于生物技术和基础研究应用，以及表征细菌和质体细菌型转录系统之间的进化差异。
