Structural analysis of an eIF3 subcomplex reveals conserved interactions required for a stable and proper translation pre-initiation complex assembly
Anna Herrmannová,Dalia Daujotytė,Ji-Chun Yang,Lucie Cuchalová,Fabrice Gorrec,Susan Wagner,István Dányi,Peter J. Lukavsky,Leoš Shivaya Valášek +8 more
TLDR
It is concluded that the C-terminus of eIF3b/PRT1 orchestrates co-operative recruitment of eif3i/TIF34 and eIF 3g/Tif35 to the 40S subunit for a stable and proper assembly of 48S pre-initiation complexes necessary for stringent AUG recognition on mRNAs.Abstract:
Translation initiation factor eIF3 acts as the key orchestrator of the canonical initiation pathway in eukaryotes, yet its structure is greatly unexplored. We report the 2.2 A resolution crystal structure of the complex between the yeast seven-bladed β-propeller eIF3i/TIF34 and a C-terminal α-helix of eIF3b/PRT1, which reveals universally conserved interactions. Mutating these interactions displays severe growth defects and eliminates association of eIF3i/TIF34 and strikingly also eIF3g/TIF35 with eIF3 and 40S subunits in vivo. Unexpectedly, 40S-association of the remaining eIF3 subcomplex and eIF5 is likewise destabilized resulting in formation of aberrant pre-initiation complexes (PICs) containing eIF2 and eIF1, which critically compromises scanning arrest on mRNA at its AUG start codon suggesting that the contacts between mRNA and ribosomal decoding site are impaired. Remarkably, overexpression of eIF3g/TIF35 suppresses the leaky scanning and growth defects most probably by preventing these aberrant PICs to form. Leaky scanning is also partially suppressed by eIF1, one of the key regulators of AUG recognition, and its mutant sui1(G107R) but the mechanism differs. We conclude that the C-terminus of eIF3b/PRT1 orchestrates co-operative recruitment of eIF3i/TIF34 and eIF3g/TIF35 to the 40S subunit for a stable and proper assembly of 48S pre-initiation complexes necessary for stringent AUG recognition on mRNAs.read more
Citations
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Journal ArticleDOI
The Scanning Mechanism of Eukaryotic Translation Initiation
TL;DR: In eukaryotes, the translation initiation codon is generally identified by the scanning mechanism, wherein every triplet in the messenger RNA leader is inspected for complementarity to the anticodon of methionyl initiator transfer RNA (Met-tRNAi).
Journal ArticleDOI
A mechanistic overview of translation initiation in eukaryotes
TL;DR: The current understanding of eukaryotic translation initiation is outlined, key molecular events in this critical phase of gene expression are illuminated and important outstanding challenges are discussed.
Journal ArticleDOI
Structural Insights into the Mechanism of Scanning and Start Codon Recognition in Eukaryotic Translation Initiation
TL;DR: High-resolution structures of PICs assembled with different ligands reveal that the eIF3 complex interacts with multiple functional sites in the PIC, rationalizing its participation in numerous steps of initiation and restricting to AUG codons the transition to the closed conformation.
Journal ArticleDOI
Structure of mammalian eIF3 in the context of the 43S preinitiation complex
Amedee des Georges,Vidya Dhote,Lauriane Kuhn,Christopher U.T. Hellen,Tatyana V. Pestova,Joachim Frank,Yaser Hashem +6 more
TL;DR: A cryo-electron microscopy structure of eIF3 is presented in the context of the DHX29-bound 43S complex, showing the PCI/MPN core at ∼6 Å resolution and revealing the organization of the individual subunits and their interactions with components of the 43Scomplex.
Journal ArticleDOI
Molecular Architecture of the 40S⋅eIF1⋅eIF3 Translation Initiation Complex.
Jan P. Erzberger,Florian Stengel,Riccardo Pellarin,S. Zhang,Tanja Schaefer,Christopher H. S. Aylett,Peter Cimermancic,Daniel Boehringer,Andrej Sali,Ruedi Aebersold,Ruedi Aebersold,Nenad Ban +11 more
TL;DR: X-ray structures of all major components of the minimal, six-subunit Saccharomyces cerevisiae eIF3 core are presented, revealing an extended, modular arrangement of eIF2 subunits and 43S ribosomal subunit complex.
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