Development of plant vectors carrying translational enhancers

翻译增强子是增强所编码蛋白质的翻译效率的mRNA基序。在本研究之前，我们在转基因烟草的研究中发现了两个植物翻译增强子元件。因此，本项目的初步计划是将这些基序应用于建立新的高翻译效率的植物表达载体。然而，在研究的中途，我们发现上述基序的翻译增强子效应根据侧翼序列（包括5' UTR内的序列和编码区中的序列）而发生很大变化。因此，使用上述基序不太可能建立可靠的表达载体。我们的最终目标是建立一种可靠的方法来提高植物基因工程的翻译效率。我们在1999年改变了这个项目的过程，以追求使我们能够获得针对任何给定mRNA的翻译增强子的方法。经过两年的试验和错误，我们终于创造了一种满足这些要求的新方法。该方法基于体外进化理论和PCR技术，是第一种可靠的分离翻译增强子的方法。

Translational enhancers are mRNA motifs that enhance translational efficiency of encoded proteins. In advance of this research project, we had found two translational enhancer elements of plants from the studies with transgenic tobacco. Hence, the initial plan of this project was to apply those motifs in establishing new plant expression vectors of high translation efficiency. However, halfway the research period, we found that the translational enhancer effects of above motifs greatly alter according to the flanking sequences including those within the 5' UTR and in the coding region. Thus, it became unlikely to establish reliable expression vectors using above motifs. Our ultimate goal was to establish a reliable method to improve translation efficiency in plant gene engineering. We altered the course of this project in 1999 for pursuing the method that enables us to obtain translational enhancers against any given mRNAs. After two years of trial and error, we finally created a novel method fulfilling these requirements. This method is based on the in vitro evolution theory and PCR technology, and is the first reliable method to isolate translational enhancers.