Human eukaryotic initiation factor 4G (eIF4G) protein binds to eIF3c, -d, and -e to promote mRNA recruitment to the ribosome

Nancy Villa, Angelie Do, John W B Hershey, Christopher S. Fraser

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

Recruitment of mRNA to the 40S ribosomal subunit requires the coordinated interaction of a large number of translation initiation factors. In mammals, the direct interaction between eukaryotic initiation factor4G(eIF4G) and eIF3 is thought to act as the molecular bridge between the mRNA cap-binding complex and the 40S subunit. A discrete ∼90 amino acid domain in eIF4G is responsible for binding to eIF3, but the identity of the eIF3 subunit(s) involved is less clear. The eIF3e subunit has been shown to directly bind eIF4G, but the potential role of other eIF3 subunits in stabilizing this interaction has not been investigated. It is also not clear if the eIF4A helicase plays a role in stabilizing the interaction between eIF4G and eIF3. Here, we have used a fluorescence anisotropy assay to demonstrate that eIF4G binds to eIF3 independently of eIF4A binding to the middle region of eIF4G. By using a site-specific cross-linking approach, we unexpectedly show that the eIF4G-binding surface in eIF3 is comprised of the -c, -d and -e subunits. Screening multiple cross-linker positions reveals that eIF4G contains two distinct eIF3-binding subdomains within the previously identified eIF3- binding domain. Finally, by employing an eIF4G-dependent translation assay, we establish that both of these subdomains are required for efficient mRNA recruitment to the ribosome and stimulate translation. Our study reveals unexpected complexity to the eIF3-eIF4G interaction that provides new insight into the regulation of mRNA recruitment to the human ribosome.

Original languageEnglish (US)
Pages (from-to)32932-32940
Number of pages9
JournalJournal of Biological Chemistry
Volume288
Issue number46
DOIs
StatePublished - Nov 15 2013

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Eukaryotic Initiation Factor-4G
Ribosomes
Messenger RNA
Proteins
Assays
Eukaryotic Small Ribosome Subunits
Peptide Initiation Factors
Fluorescence Polarization
Mammals
Screening
Anisotropy

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Human eukaryotic initiation factor 4G (eIF4G) protein binds to eIF3c, -d, and -e to promote mRNA recruitment to the ribosome. / Villa, Nancy; Do, Angelie; Hershey, John W B; Fraser, Christopher S.

In: Journal of Biological Chemistry, Vol. 288, No. 46, 15.11.2013, p. 32932-32940.

Research output: Contribution to journalArticle

Villa, Nancy ; Do, Angelie ; Hershey, John W B ; Fraser, Christopher S. / Human eukaryotic initiation factor 4G (eIF4G) protein binds to eIF3c, -d, and -e to promote mRNA recruitment to the ribosome. In: Journal of Biological Chemistry. 2013 ; Vol. 288, No. 46. pp. 32932-32940.
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abstract = "Recruitment of mRNA to the 40S ribosomal subunit requires the coordinated interaction of a large number of translation initiation factors. In mammals, the direct interaction between eukaryotic initiation factor4G(eIF4G) and eIF3 is thought to act as the molecular bridge between the mRNA cap-binding complex and the 40S subunit. A discrete ∼90 amino acid domain in eIF4G is responsible for binding to eIF3, but the identity of the eIF3 subunit(s) involved is less clear. The eIF3e subunit has been shown to directly bind eIF4G, but the potential role of other eIF3 subunits in stabilizing this interaction has not been investigated. It is also not clear if the eIF4A helicase plays a role in stabilizing the interaction between eIF4G and eIF3. Here, we have used a fluorescence anisotropy assay to demonstrate that eIF4G binds to eIF3 independently of eIF4A binding to the middle region of eIF4G. By using a site-specific cross-linking approach, we unexpectedly show that the eIF4G-binding surface in eIF3 is comprised of the -c, -d and -e subunits. Screening multiple cross-linker positions reveals that eIF4G contains two distinct eIF3-binding subdomains within the previously identified eIF3- binding domain. Finally, by employing an eIF4G-dependent translation assay, we establish that both of these subdomains are required for efficient mRNA recruitment to the ribosome and stimulate translation. Our study reveals unexpected complexity to the eIF3-eIF4G interaction that provides new insight into the regulation of mRNA recruitment to the human ribosome.",
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