An mRNA-binding channel in the ES6S region of the translation 48S-PIC promotes RNA unwinding and scanning

Loading of mRNA onto the ribosomal 43S pre-initiation complex (PIC) and its subsequent scanning require the removal of the secondary structure of the by RNA helicases such as eIF4A. However, the topology and mechanics of the scanning complex bound to mRNA (48S-PIC) and the influence of its solvent-s...

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Bibliographic Details
Published in:eLife 2019-12, Vol.8
Main Authors: Díaz-López, Irene, Toribio, René, Berlanga, Juan José, Ventoso, Iván
Format: Article
Language:English
Subjects:
5' Untranslated Regions - genetics
Analysis
Cellular signal transduction
Chromosomes and Gene Expression
ES6S region
Eukaryotic Initiation Factor-4F - genetics
G quadruplex
G-Quadruplexes
Genomes
Genomics
Initiation complex
Mammals
Messenger RNA
mRNA
mRNA secondary structure
Peptide Chain Initiation, Translational - genetics
Protein Biosynthesis - genetics
Protein structure
Proteins
Ribosomes - genetics
RNA
RNA Helicases - chemistry
RNA Helicases - genetics
RNA, Messenger - chemistry
RNA, Messenger - genetics
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae Proteins - genetics
Scanning
Secondary structure
Signal transduction
Solvents
Transduction, Genetic
Translation
Translation (Genetics)
Unwinding
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Summary:Loading of mRNA onto the ribosomal 43S pre-initiation complex (PIC) and its subsequent scanning require the removal of the secondary structure of the by RNA helicases such as eIF4A. However, the topology and mechanics of the scanning complex bound to mRNA (48S-PIC) and the influence of its solvent-side composition on the scanning process are poorly known. Here, we found that the ES6S region of the 48S-PIC constitutes an extended binding channel for eIF4A-mediated unwinding of mRNA and scanning. Blocking ES6S inhibited the cap-dependent translation of mRNAs that have structured 5' UTRs (including G-quadruplexes), many of which are involved in signal transduction and growth, but it did not affect IRES-driven translation. Genome-wide analysis of mRNA translation revealed a great diversity in ES6S-mediated scanning dependency. Our data suggest that mRNA threading into the ES6S region makes scanning by 48S PIC slower but more processive. Hence, we propose a topological and functional model of the scanning 48S-PIC.
ISSN:2050-084X
2050-084X
DOI:10.7554/eLife.48246