Identification of domains within the ε-subunit of the translation initiation factor eIF2B that are necessary for guanine nucleotide exchange activity and eIF2B holoprotein formation

Tracy Anthony, John R. Fabian, Scot R. Kimball, Leonard S. Jefferson

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Eukaryotic translation initiation factor, eIF2B, is a guanine nucleotide exchange factor (GEF) composed of five dissimilar subunits. eIF2B is important for regenerating GTP-bound eIF2 during the initiation process. This event is obligatory for eIF2 to bind initiator methionyl-tRNA, forming the ternary initiation complex. In the current investigation, deletion mutants of the catalytic subunit, eIF2Bε, were constructed to identify regions that are necessary for eIF2B catalytic activity and formation of the holoprotein. We used the baculovirus expression system to coexpress wild-type and truncated forms of the ε-subunit of mammalian eIF2B (eIF2Bε) with the other four subunits (α, β, γ, δ) of the protein in Sf9 cells. Removal of either the N- or the C-terminal conserved domains of eIF2Bε resulted in a significant loss of GEF activity and reduced or abolished interaction with the α-, γ- and δ-subunits of eIF2B. Removal of the C-terminal 552 amino acids of eIF2Bε markedly reduced its interaction with the β-subunit of eIF2 whereas loss of the N-terminal 431 amino acids did not. The results suggest that intact eIF2Bε is required for full catalytic activity and formation of the eIF2B holoprotein. In contrast, the C-terminal domain of eIF2Bε is sufficient alone for binding the β-subunit of its substrate, eIF2, in vitro. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)56-62
Number of pages7
JournalBiochimica et Biophysica Acta - Gene Structure and Expression
Volume1492
Issue number1
DOIs
StatePublished - Jun 21 2000
Externally publishedYes

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Guanine Nucleotide Exchange Factors
Peptide Initiation Factors
Guanine Nucleotides
Catalyst activity
RNA, Transfer, Met
Eukaryotic Initiation Factors
Sf9 Cells
Amino Acids
Baculoviridae
Protein Subunits
Transfer RNA
Guanosine Triphosphate
Catalytic Domain
Substrates
In Vitro Techniques

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Genetics
  • Structural Biology
  • Biophysics

Cite this

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title = "Identification of domains within the ε-subunit of the translation initiation factor eIF2B that are necessary for guanine nucleotide exchange activity and eIF2B holoprotein formation",
abstract = "Eukaryotic translation initiation factor, eIF2B, is a guanine nucleotide exchange factor (GEF) composed of five dissimilar subunits. eIF2B is important for regenerating GTP-bound eIF2 during the initiation process. This event is obligatory for eIF2 to bind initiator methionyl-tRNA, forming the ternary initiation complex. In the current investigation, deletion mutants of the catalytic subunit, eIF2Bε, were constructed to identify regions that are necessary for eIF2B catalytic activity and formation of the holoprotein. We used the baculovirus expression system to coexpress wild-type and truncated forms of the ε-subunit of mammalian eIF2B (eIF2Bε) with the other four subunits (α, β, γ, δ) of the protein in Sf9 cells. Removal of either the N- or the C-terminal conserved domains of eIF2Bε resulted in a significant loss of GEF activity and reduced or abolished interaction with the α-, γ- and δ-subunits of eIF2B. Removal of the C-terminal 552 amino acids of eIF2Bε markedly reduced its interaction with the β-subunit of eIF2 whereas loss of the N-terminal 431 amino acids did not. The results suggest that intact eIF2Bε is required for full catalytic activity and formation of the eIF2B holoprotein. In contrast, the C-terminal domain of eIF2Bε is sufficient alone for binding the β-subunit of its substrate, eIF2, in vitro. Copyright (C) 2000 Elsevier Science B.V.",
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TY - JOUR

T1 - Identification of domains within the ε-subunit of the translation initiation factor eIF2B that are necessary for guanine nucleotide exchange activity and eIF2B holoprotein formation

AU - Anthony, Tracy

AU - Fabian, John R.

AU - Kimball, Scot R.

AU - Jefferson, Leonard S.

PY - 2000/6/21

Y1 - 2000/6/21

N2 - Eukaryotic translation initiation factor, eIF2B, is a guanine nucleotide exchange factor (GEF) composed of five dissimilar subunits. eIF2B is important for regenerating GTP-bound eIF2 during the initiation process. This event is obligatory for eIF2 to bind initiator methionyl-tRNA, forming the ternary initiation complex. In the current investigation, deletion mutants of the catalytic subunit, eIF2Bε, were constructed to identify regions that are necessary for eIF2B catalytic activity and formation of the holoprotein. We used the baculovirus expression system to coexpress wild-type and truncated forms of the ε-subunit of mammalian eIF2B (eIF2Bε) with the other four subunits (α, β, γ, δ) of the protein in Sf9 cells. Removal of either the N- or the C-terminal conserved domains of eIF2Bε resulted in a significant loss of GEF activity and reduced or abolished interaction with the α-, γ- and δ-subunits of eIF2B. Removal of the C-terminal 552 amino acids of eIF2Bε markedly reduced its interaction with the β-subunit of eIF2 whereas loss of the N-terminal 431 amino acids did not. The results suggest that intact eIF2Bε is required for full catalytic activity and formation of the eIF2B holoprotein. In contrast, the C-terminal domain of eIF2Bε is sufficient alone for binding the β-subunit of its substrate, eIF2, in vitro. Copyright (C) 2000 Elsevier Science B.V.

AB - Eukaryotic translation initiation factor, eIF2B, is a guanine nucleotide exchange factor (GEF) composed of five dissimilar subunits. eIF2B is important for regenerating GTP-bound eIF2 during the initiation process. This event is obligatory for eIF2 to bind initiator methionyl-tRNA, forming the ternary initiation complex. In the current investigation, deletion mutants of the catalytic subunit, eIF2Bε, were constructed to identify regions that are necessary for eIF2B catalytic activity and formation of the holoprotein. We used the baculovirus expression system to coexpress wild-type and truncated forms of the ε-subunit of mammalian eIF2B (eIF2Bε) with the other four subunits (α, β, γ, δ) of the protein in Sf9 cells. Removal of either the N- or the C-terminal conserved domains of eIF2Bε resulted in a significant loss of GEF activity and reduced or abolished interaction with the α-, γ- and δ-subunits of eIF2B. Removal of the C-terminal 552 amino acids of eIF2Bε markedly reduced its interaction with the β-subunit of eIF2 whereas loss of the N-terminal 431 amino acids did not. The results suggest that intact eIF2Bε is required for full catalytic activity and formation of the eIF2B holoprotein. In contrast, the C-terminal domain of eIF2Bε is sufficient alone for binding the β-subunit of its substrate, eIF2, in vitro. Copyright (C) 2000 Elsevier Science B.V.

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