Structural Insights into the Mammalian Late-Stage Initiation Complexes

By A. Simonetti, E. Guca, A. Bochler, L. Kuhn, Y. Hashem. 2020

68 citations recorded by the source corpus.

Summary In higher eukaryotes, the mRNA sequence in the direct vicinity of the start codon, called the Kozak sequence (CRCCaugG, where R is a purine), is known to influence the rate of the initiation process. However, the molecular basis underlying its role remains poorly understood. Here, we present the cryoelectron microscopy (cryo-EM) structures of mammalian late-stage 48S initiation complexes (LS48S ICs) in the presence of two different native mRNA sequences, β-globin and histone 4, at overall resolution of 3 and 3.5 Å, respectively. Our high-resolution structures unravel key interactions from the mRNA to eukaryotic initiation factors (eIFs): 1A, 2, 3, 18S rRNA, and several 40S ribosomal proteins. In addition, we are able to study the structural role of ABCE1 in the formation of native 48S ICs. Our results reveal a comprehensive map of ribosome/eIF-mRNA and ribosome/eIF-tRNA interactions and suggest the impact of mRNA sequence on the structure of the LS48S IC.

Subfields: Molecular Biology

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Citations in the corpus

Dynamic competition between SARS-CoV-2 NSP1 and mRNA on the human ribosome inhibits translation initiation (2020, methodology): “The following Protein Data Bank (PDB) models were used: PDB ID codes 4UG0 (75), 5A2Q (38), 6ZLW (19), 6YAL (76), and 6ZMW (33).”