Translation Enhancer Improves the Ribosome Liberation from Translation Initiation

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• 作者：Shuntaro Takahashi ; Hiroyuki Furusawa ; Takuya Ueda ; Yoshio Okahata
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：September 4, 2013
• 年：2013
• 卷：135
• 期：35
• 页码：13096-13106
• 全文大小：533K
• 年卷期：v.135,no.35(September 4, 2013)
• ISSN：1520-5126

文摘

For translation initiation in bacteria, the Shine鈥揇algarno (SD) and anti-SD sequence of the 30S subunit play key roles for specific interactions between ribosomes and mRNAs to determine the exact position of the translation initiation region. However, ribosomes also must dissociate from the translation initiation region to slide toward the downstream sequence during mRNA translation. Translation enhancers upstream of the SD sequences of mRNAs, which likely contribute to a direct interaction with ribosome protein S1, enhance the yields of protein biosynthesis. Nevertheless, the mechanism of the effect of translation enhancers to initiate the translation is still unknown. In this paper, we investigated the effects of the SD and enhancer sequences on the binding kinetics of the 30S ribosomal subunits to mRNAs and their translation efficiencies. mRNAs with both the SD and translation enhancers promoted the amount of protein synthesis but destabilized the interaction between the 30S subunit and mRNA by increasing the dissociation rate constant (k_off) of the 30S subunit. Based on a model for kinetic parameters, a 16-fold translation efficiency could be achieved by introducing a tandem repeat of adenine sequences (A20) between the SD and translation enhancer sequences. Considering the results of this study, translation enhancers with an SD sequence regulate ribosomal liberation from translation initiation to determine the translation efficiency of the downstream coding region.