Effect of structure of the initiator codon on translation in <i>E. coli</i>

Khudyakov, Yuri; Neplyueva, V.S.; Kalinina, T.I.; Smirnov, V. D.

doi:10.1016/0014-5793(88)80771-3

Cited by 14 publications

(12 citation statements)

References 14 publications

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“…7B,C). Intriguingly, both corL and mgtM use the inefficient start codon UUG, which could be especially sensitive to global changes in translation, such as ribosome availability 37 . Because the majority of cytosolic Mg 2+ is devoted to maintenance of ribosome structure and activity, an increase in Mg 2+ uptake may help the cell cope with translational stressors 38 .…”

Section: Discussionmentioning

confidence: 99%

The Bacterial Transcription Termination Factor Rho Coordinates Mg2+ Homeostasis with Translational Signals

Kriner

Groisman

2015

Journal of Molecular Biology

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The bacterial protein Rho triggers transcription termination at the ends of many operons and when transcription and translation become uncoupled. In addition to these genome-wide activities, Rho implements regulation of specific genes by dictating whether RNA polymerase terminates transcription within the 5’ leader region or continues into the downstream coding region. Here, we report that the Mg2+ channel gene corA in Salmonella enterica serovar Typhimurium, which was previously thought to be constitutively expressed, is regulated by a Rho-dependent terminator located within its 5’ leader region. We demonstrate that the unusually long and highly conserved corA leader mRNA can adopt two mutually exclusive conformations that determine whether or not Rho interacts with a Rho utilization (rut) site on the nascent RNA and thereby prevents transcription of the corA coding region. The RNA conformation that promotes Rho-dependent termination is favored by efficient translation of corL, a short open reading frame located within the corA leader. Thus, corA transcription is inversely coupled to corL translation. This mechanism resembles those governing expression of Salmonella’s other two Mg2+ transport genes, suggesting that Rho links Mg2+ uptake to translational signals.

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Section: Discussionmentioning

confidence: 99%

The Bacterial Transcription Termination Factor Rho Coordinates Mg2+ Homeostasis with Translational Signals

Kriner

Groisman

2015

Journal of Molecular Biology

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“…Nevertheless, in prokaryotes this triplet is fairly degenerate because, in addition to the most common "best-fit" AUG, other rare 3' or 5' wobbling codons (i.e., GUG, UUG, AUA, AUU) are occasionally found as translational starts. Changing these rare codons to AUG sometimes resulted in moderate (4,5) or large (6, 7) increases of expression, suggesting that the rare triplets may be used to slow down the expression of some select genes. The catalogue of genes starting with the rare triplets, which includes some of the most abundantly expressed genes in Escherichia coli, such as tufA (elongation factor Tu, ref.…”

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confidence: 99%

Translation of mRNAs with degenerate initiation triplet AUU displays high initiation factor 2 dependence and is subject to initiation factor 3 repression.

Teana

Pon

Gualerzi

1993

Proc. Natl. Acad. Sci. U.S.A.

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The influence of the rare initiation triplet AUU on mRNA translation was investigated by comparing the activity of two pairs of model mRNAs that differ in the length of Shine-Dalgarno and spacer sequences. Irrespective of the initiation triplet (AUG or AUU), all mRNAs had similar template activity in vitro, but translation of AUU mRNAs depended more on initiation factor (IF) 2 and less on IF3 than that of AUG mRNAs. Increasing the IF3/ribosome ratio from 2 to 10 progressively inhibited the AUU mRNAs and abolished their capacity to compete for translating ribosomes with other mRNAs but did not affect activity of the AUG mRNAs. The effects induced by IF3 are from its different influence on onand off-rates of the transition 30S preinitiation complex -30S initiation complex; depending on the nature of the initiation triplet (AUG or AUU) of the mRNA, IF3 shifts the position of equilibrium toward binding or dissociation of fMet-tRNA, respectively. Stimulation of fMet-tRNA binding and dissociation yields superimposable IF3 titration curves that saturate at an IF3/30S ratio of -1, indicating that the data are from the interaction of one molecule of IF3 with the same 30S binding site. Both effects are either lost or strongly reduced with 30S mutants defective in IF3 binding. Translational repression of AUU mRNAs by IF3 is from the factor-dependent dissociation of fMet-tRNA from 30S subunits, which becomes relevant when excess IF3 interferes with the formation of 70S initiation complex, presumably by interacting with 50S subunit.

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“…Mutagenesis of the UUG initiation triplet of the cyaA gene has shown that initiation codons UUG, GUG and AUG directed the synthesis of adenylate cyclase at relative levels of 1:2:6, respectively (28). In another case, lacZ translation from GUG and UUG (53) or AUC (54) codons instead of AUG was reduced two- to three-times; likewise, a truncated form of bacteriophage HB-3 murein hydrolase was synthesized in E. coli with an efficiency of 7.5 and 5% when instead of AUG the initiation codon was AUA and AUU or AUC (54). …”

Section: Resultsmentioning

confidence: 99%

“…For instance, the nature of the +2 codon was shown to be one of the determinants for the high translational efficiency of an mRNA beginning with UUG but not of a GUG start codon (62); likewise, a change in the initiation codon from AUG to AUA, which did not affect mRNA binding by ribosomes in the case of phage T7 0.3 gene (52), reduced the binding to the Qβ coat protein cistron to <10 and to 30% if the initiation triplet was followed by a G and by an A, respectively (63). Finally, the relative amounts of adenylate cyclase synthesized from initiation codons UUG, GUG and AUG is 1:2:6 when the triplets are located within the cyaA mRNA TIR but become 1:2:3 when the translation is driven from a lacZ fusion (53). …”

Section: Discussionmentioning

confidence: 99%

Ribosomal selection of mRNAs with degenerate initiation triplets

Sabatini

Brandi

et al. 2017

Nucleic Acids Research

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To assess the influence of degenerate initiation triplets on mRNA recruitment by ribosomes, five mRNAs identical but for their start codon (AUG, GUG, UUG, AUU and AUA) were offered to a limiting amount of ribosomes, alone or in competition with an identical AUGmRNA bearing a mutation conferring different electrophoretic mobility to the product. Translational efficiency and competitiveness of test mRNAs toward this AUGmRNA were determined quantifying the relative amounts of the electrophoretically separated wt and mutated products synthesized in vitro and found to be influenced to different extents by the nature of their initiation triplet and by parameters such as temperature and nutrient availability in the medium. The behaviors of AUAmRNA, UUGmRNA and AUGmRNA were the same between 20 and 40°C whereas the GUG and AUUmRNAs were less active and competed poorly with the AUGmRNA, especially at low temperature. Nutrient limitation and preferential inhibition by ppGpp severely affected activity and competitiveness of all mRNAs bearing non-AUG starts, the UUGmRNA being the least affected. Overall, our data indicate that beyond these effects exclusively due to the degenerate start codons within an optimized translational initiation region, an important role is played by the context in which the rare start codons are present.

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Effect of structure of the initiator codon on translation in E. coli

Cited by 14 publications

References 14 publications

The Bacterial Transcription Termination Factor Rho Coordinates Mg2+ Homeostasis with Translational Signals

The Bacterial Transcription Termination Factor Rho Coordinates Mg2+ Homeostasis with Translational Signals

Translation of mRNAs with degenerate initiation triplet AUU displays high initiation factor 2 dependence and is subject to initiation factor 3 repression.

Ribosomal selection of mRNAs with degenerate initiation triplets

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