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A network of eIF2β interactions with eIF1 and Met-tRNAi promotes accurate start codon selection by the translation preinitiation complex
- Source :
- Nucleic Acids Research
- Publication Year :
- 2018
- Publisher :
- Oxford University Press, 2018.
-
Abstract
- In translation initiation, a 43S preinitiation complex (PIC) containing eIF1 and a ternary complex (TC) of GTP-bound eIF2 and Met-RNAi scans the mRNA for the start codon. AUG recognition triggers eIF1 release and rearrangement from an open PIC conformation to a closed state with more tightly-bound Met-tRNAi (PIN state). Cryo-EM models reveal eIF2β contacts with eIF1 and Met-tRNAi exclusive to the open complex that should destabilize the closed state. eIF2β or eIF1 substitutions disrupting these contacts increase initiation at UUG codons, and compound substitutions also derepress translation of GCN4, indicating slower TC recruitment. The latter substitutions slow TC loading while stabilizing TC binding at UUG codons in reconstituted PICs, indicating a destabilized open complex and shift to the closed/PIN state. An eIF1 substitution that should strengthen the eIF2β:eIF1 interface has the opposite genetic and biochemical phenotypes. eIF2β is also predicted to restrict Met-tRNAi movement into the closed/PIN state, and substitutions that should diminish this clash increase UUG initiation in vivo and stabilize Met-tRNAi binding at UUG codons in vitro with little effect on TC loading. Thus, eIF2β anchors eIF1 and TC to the open complex, enhancing PIC assembly and scanning, while impeding rearrangement to the closed conformation at non-AUG codons.
- Subjects :
- RNA, Transfer, Met
Saccharomyces cerevisiae Proteins
Translation preinitiation complex
Eukaryotic Initiation Factor-1
Codon, Initiator
Saccharomyces cerevisiae
Ternary Complex Factors
Biology
03 medical and health sciences
0302 clinical medicine
Eukaryotic translation
Start codon
Genetics
RNA and RNA-protein complexes
Peptide Chain Initiation, Translational
Ternary complex
030304 developmental biology
0303 health sciences
eIF2
Cryoelectron Microscopy
Translation (biology)
EIF1
Eukaryotic Initiation Factor-2B
Basic-Leucine Zipper Transcription Factors
Protein Biosynthesis
Transcription preinitiation complex
Biophysics
030217 neurology & neurosurgery
Subjects
Details
- Language :
- English
- ISSN :
- 13624962 and 03051048
- Volume :
- 47
- Issue :
- 5
- Database :
- OpenAIRE
- Journal :
- Nucleic Acids Research
- Accession number :
- edsair.doi.dedup.....d376a2d515a8100fcdb9cad4014f0d0b