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Biggin, M. D.

Publications and source records attributed to Biggin, M. D..

2 recordsLinked to original sources

Quantitation of cis-translational control by general mRNA sequence features in five eukaryotes

BACKGROUNDGeneral translational cis-elements are present in the mRNAs of all genes and affect the recruitment, assembly, and progress of preinitiation complexes and the ribosome under many physiological states. These elements are: mRNA folding, upstream open reading frames, specific nucleotides flanking the initiating AUG codon, protein coding sequence length, and codon usage. The quantitative contributions of these sequence features and how and why they coordinate together to control translation rates are not well understood.\n\nRESULTSHere we show that these sequence features specify 42%-81% of the variance in translation rates in S. cerevisiae, S. pombe, Arabidopsis thaliana, M. musculus, and H. Sapiens. We establish that control by RNA secondary structure is chiefly mediated by highly folded 25-60 nucleotide segments within mRNA 5 regions; that changes in tri-nucleotide frequencies between highly and poorly translated 5 regions are correlated between all species; and that control by distinct biochemical processes is extensively correlated as is regulation by a single process acting in different parts of the same mRNA.\n\nCONCLUSIONSOur work shows that the general features control a much larger fraction of the variance in translation rates than previously realized. We provide a more detailed and accurate understanding of the aspects of RNA structure that direct translation in diverse eukaryotes. In addition, we note that the strongly correlated regulation between and within cis-control features will cause more even densities of translational complexes along each mRNA and therefore more efficient use of the translation machinery by the cell.

genomics↗

Quantitating Translational Control: mRNA Abundance-Dependent and Independent Contributions

Translation rate per mRNA molecule correlates positively with mRNA abundance. As a result, protein levels do not scale linearly with mRNA levels, but instead scale with the abundance of mRNA raised to the power of an \"amplification exponent\". Here we show that to quantitate translational control, the translation rate must be decomposed into two components. One, TRmD, depends on the mRNA level and defines the amplification exponent. The other, TRmIND, is independent of mRNA amount and impacts the correlation coefficient between protein and mRNA levels. We show that in S. cerevisiae TRmD represents [~]20% of the variance in translation and directs an amplification exponent of 1.20 with a 95% confidence interval [1.14, 1.26]. TRmIND constitutes the remaining [~]80% of the variance in translation and explains [~]5% of the variance in protein expression. We also find that TRmD and TRmIND are preferentially determined by different mRNA sequence features: TRmIND by the length of the open reading frame and TRmD both by a [~]60 nucleotide element that spans the initiating AUG and by codon and amino acid frequency. Our work provides more appropriate estimates of translational control and implies that TRmIND is under different evolutionary selective pressures than TRmD.

genomics↗