文章基本信息

标题：Biochemical and functional analysis of a 9-nt RNA sequence that affects translation efficiency in eukaryotic cells
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作者：Stephen A. Chappell ; Gerald M. Edelman ; Vincent P. Mauro 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：26
页码：9590-9594
DOI：10.1073/pnas.0308759101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We previously identified an internal ribosome entry site (IRES) within the 5' leader of the mRNA encoding the Gtx homeodomain protein and showed that shorter nonoverlapping segments of this 5' leader could enhance the translation of a second cistron in a dicistronic mRNA. One of these segments was 9 nt in length, and when multiple copies of this IRES module were linked together, IRES activity was greatly enhanced. To further expand the potential uses of these synthetic constructs and facilitate analyses of the mechanism by which they affect translation, we show here that an IRES containing five linked copies of the 9-nt sequence can also enhance translation in the 5' leader of a monocistronic mRNA. Moreover, a search for interactions of the IRES module with cellular factors revealed specific binding to 40S ribosomal subunits but not to other cellular components. Based on the results of earlier studies suggesting that this sequence could bind to a complementary segment of 18S rRNA, we tested various sequences for possible links between the length of the complementary match, their binding to ribosomes, and their influence on translational efficiency. We found that the length of the complementary match was directly correlated with the ability of RNA probes to bind to ribosomes. In addition, translation was maximally enhanced ({approx}8-fold) by a 7-nt segment of the 9-nt element; the enhancement declined progressively as the complementary stretches became progressively longer or shorter. The results suggest that the Gtx 9-nt sequence affects translation efficiency by a mechanism that involves base pairing to 18S rRNA.