Determinant Of Translation Efficiency Research Articles

Shine-Dalgarno Sequences Play an Essential Role in the Translation of Plastid mRNAs in Tobacco.

In prokaryotic systems, the translation initiation of many, though not all, mRNAs depends on interaction between a sequence element upstream of the start codon (the Shine-Dalgarno sequence [SD]) and a complementary sequence in the 3' end of the 16S rRNA (anti-Shine-Dalgarno sequence [aSD]). Although many chloroplast mRNAs harbor putative SDs in their 5' untranslated regions and the aSD displays strong conservation, the functional relevance of SD-aSD interactions in plastid translation is unclear. Here, by generating transplastomic tobacco (Nicotiana tabacum) mutants with point mutations in the aSD coupled with genome-wide analysis of translation by ribosome profiling, we provide a global picture of SD-dependent translation in plastids. We observed a pronounced correlation between weakened predicted SD-aSD interactions and reduced translation efficiency. However, multiple lines of evidence suggest that the strength of the SD-aSD interaction is not the only determinant of the translational output of many plastid mRNAs. Finally, the translation efficiency of mRNAs with strong secondary structures around the start codon is more dependent on the SD-aSD interaction than weakly structured mRNAs. Thus, our data reveal the importance of the aSD in plastid translation initiation, uncover chloroplast genes whose translation is influenced by SD-aSD interactions, and provide insights into determinants of translation efficiency in plastids.

Determinants of translation efficiency of specific mRNAs in mammalian cells.

The means by which the ribosomes of mammalian cells recognize translation initiation sites and the structural features of an mRNA that define its overall translation efficiency are only partially understood. Even so, an effort to engineer the efficient translation of a specific sequence in mammalian cells can benefit from existing information about mechanisms of translation initiation. The purpose of this article is to review briefly our present knowledge of the factors that influence translation efficiency and to suggest some means by which this knowledge can be exploited to influence the translation efficiency of a specific mRNA.