Binding of eIF3 in complex with eIF5 and eIF1 to the 40S ribosomal subunit is accompanied by dramatic structural changes.
Nucleic Acids Res
; 47(15): 8282-8300, 2019 09 05.
Article
in En
| MEDLINE
| ID: mdl-31291455
ABSTRACT
eIF3 is a large multiprotein complex serving as an essential scaffold promoting binding of other eIFs to the 40S subunit, where it coordinates their actions during translation initiation. Perhaps due to a high degree of flexibility of multiple eIF3 subunits, a high-resolution structure of free eIF3 from any organism has never been solved. Employing genetics and biochemistry, we previously built a 2D interaction map of all five yeast eIF3 subunits. Here we further improved the previously reported in vitro reconstitution protocol of yeast eIF3, which we cross-linked and trypsin-digested to determine its overall shape in 3D by advanced mass-spectrometry. The obtained cross-links support our 2D subunit interaction map and reveal that eIF3 is tightly packed with its WD40 and RRM domains exposed. This contrasts with reported cryo-EM structures depicting eIF3 as a molecular embracer of the 40S subunit. Since the binding of eIF1 and eIF5 further fortified the compact architecture of eIF3, we suggest that its initial contact with the 40S solvent-exposed side makes eIF3 to open up and wrap around the 40S head with its extended arms. In addition, we mapped the position of eIF5 to the region below the P- and E-sites of the 40S subunit.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Peptide Chain Initiation, Translational
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Eukaryotic Initiation Factor-1
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Saccharomyces cerevisiae Proteins
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Eukaryotic Initiation Factor-5
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Eukaryotic Initiation Factor-3
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Ribosome Subunits, Small, Eukaryotic
Type of study:
Prognostic_studies
Language:
En
Journal:
Nucleic Acids Res
Year:
2019
Document type:
Article