PMID:12358433
| Citation |
Komarova, AV, Tchufistova, LS, Supina, EV and Boni, IV (2002) Protein S1 counteracts the inhibitory effect of the extended Shine-Dalgarno sequence on translation. RNA 8:1137-47 |
|---|---|
| Abstract |
There are two major components of Escherichia coli ribosomes directly involved in selection and binding of mRNA during initiation of protein synthesis-the highly conserved 3' end of 16S rRNA (aSD) complementary to the Shine-Dalgarno (SD) domain of mRNA, and the ribosomal protein S1. A contribution of the SD-aSD and S1-mRNA interactions to translation yield in vivo has been evaluated in a genetic system developed to compare efficiencies of various ribosome-binding sites (RBS) in driving beta-galactosidase synthesis from the single-copy (chromosomal) lacZ gene. The in vivo experiments have been supplemented by in vitro toeprinting and gel-mobility shift assays. A shortening of a potential SD-aSD duplex from 10 to 8 and to 6 bp increased the beta-galactosidase yield (four- and sixfold, respectively) suggesting that an extended SD-aSD duplex adversely affects translation, most likely due to its redundant stability causing ribosome stalling at the initiation step. Translation yields were significantly increased upon insertion of the A/U-rich S1 binding targets upstream of the SD region, but the longest SD remained relatively less efficient. In contrast to complete 30S ribosomes, the S1-depleted 30S particles have been able to form an extended SD-aSD duplex, but not the true ternary initiation complex. Taken together, the in vivo and in vitro data allow us to conclude that S1 plays two roles in translation initiation: It forms an essential part of the mRNA-binding track even when mRNA bears a long SD sequence, and through the binding to the 5' untranslated region, it can ensure a substantial enhancing effect on translation. |
| Links | |
| Keywords |
5' Untranslated Regions; Base Sequence; Binding Sites/genetics; Enhancer Elements, Genetic; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Lac Operon; Protein Biosynthesis; RNA, Bacterial/genetics; RNA, Bacterial/metabolism; RNA, Messenger/genetics; RNA, Messenger/metabolism; Ribosomal Proteins/metabolism; Ribosomes/metabolism; beta-Galactosidase/biosynthesis; beta-Galactosidase/genetics |
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