Liu Shumo, Libchaber Albert
NEC Laboratories America, 4 Independence Way, Princeton, NJ 08540, USA.
J Mol Evol. 2006 May;62(5):536-50. doi: 10.1007/s00239-005-0128-x. Epub 2006 Apr 11.
We devised a molecular evolution procedure to evolve E. coli promoter sequences and applied it to observe an arbitrary, nonfunctional sequence evolving into functional promoters. In the experiments, DNA sequence variations were generated with error-prone PCR and were inserted in the promoter region of the cat (chloramphenicol acetyl transferase) gene on a plasmid. Upon transforming the cells, functional promoters on the plasmid were selected according to the chloramphenicol resistance. Within a few cycles of mutation-selection, promoters emerged, and the sequences converged into a small number of groups. In the process, the extended minus 10 type of promoters emerged quickly, and small deletions were often involved in adjusting the length between the -35 and the -10 elements. Our results also suggest a possible selection for promoter stability against mutation.
我们设计了一种分子进化程序来进化大肠杆菌启动子序列，并将其应用于观察一个任意的、无功能的序列进化为功能性启动子的过程。在实验中，通过易错PCR产生DNA序列变异，并将其插入到质粒上cat（氯霉素乙酰转移酶）基因的启动子区域。在转化细胞后，根据氯霉素抗性选择质粒上的功能性启动子。在几个突变-选择循环内，启动子出现了，并且序列收敛为少数几个组。在此过程中，扩展的-10型启动子迅速出现，并且小的缺失常常参与调节-35和-10元件之间的长度。我们的结果还表明可能存在针对启动子抗突变稳定性的选择。
