Structural Insights into the Mammalian Late-Stage Initiation Complexes

Angelita Simonetti; Ewelina Guca; Anthony Bochler; Lauriane Kuhn; Yaser Hashem

doi:10.1016/j.celrep.2020.03.061

Structural Insights into the Mammalian Late-Stage Initiation Complexes

Cell Rep. 2020 Apr 7;31(1):107497. doi: 10.1016/j.celrep.2020.03.061.

Authors

Angelita Simonetti¹, Ewelina Guca², Anthony Bochler³, Lauriane Kuhn⁴, Yaser Hashem⁵

Affiliations

¹ Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg 67000, France.
² INSERM U1212 Acides nucléiques: Régulations Naturelle et Artificielle (ARNA), Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France.
³ Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg 67000, France; INSERM U1212 Acides nucléiques: Régulations Naturelle et Artificielle (ARNA), Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France.
⁴ Proteomic Platform Strasbourg - Esplanade, Institut de Biologie Moléculaire et Cellulaire, CNRS, Université de Strasbourg, Strasbourg 67000, France.
⁵ INSERM U1212 Acides nucléiques: Régulations Naturelle et Artificielle (ARNA), Institut Européen de Chimie et Biologie, Université de Bordeaux, Pessac 33607, France. Electronic address: [email protected].

Abstract

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

ATP-Binding Cassette Transporters / genetics
ATP-Binding Cassette Transporters / metabolism
Animals
Codon, Initiator / genetics
Codon, Initiator / ultrastructure
Cryoelectron Microscopy / methods
Enhancer Elements, Genetic / genetics
Eukaryotic Initiation Factor-1 / genetics
Eukaryotic Initiation Factor-1 / metabolism
Eukaryotic Initiation Factor-2 / genetics
Eukaryotic Initiation Factor-2 / metabolism
Eukaryotic Initiation Factor-3 / genetics
Eukaryotic Initiation Factor-3 / metabolism
Eukaryotic Initiation Factors / metabolism*
Eukaryotic Initiation Factors / ultrastructure*
Humans
Mice
Peptide Chain Initiation, Translational
Protein Biosynthesis
RNA, Messenger / metabolism
RNA, Ribosomal, 18S / genetics
RNA, Ribosomal, 18S / metabolism
RNA, Transfer / metabolism
Ribosomal Proteins / metabolism
Ribosomes / metabolism
Transcription Initiation, Genetic / physiology*
beta-Globins / genetics
beta-Globins / ultrastructure

Substances

ATP-Binding Cassette Transporters
Codon, Initiator
Eukaryotic Initiation Factor-1
Eukaryotic Initiation Factor-2
Eukaryotic Initiation Factor-3
Eukaryotic Initiation Factors
RNA, Messenger
RNA, Ribosomal, 18S
Ribosomal Proteins
beta-Globins
eukaryotic peptide initiation factor-1A
RNA, Transfer