Identification of Intersubunit Domain Interactions within Eukaryotic Initiation Factor (eIF) 2B, the Nucleotide Exchange Factor for Translation Initiation
| Autor: | Peter J. Reid, Graham D. Pavitt, Sarah S. Mohammad-Qureshi |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Translation
Saccharomyces cerevisiae Proteins Protein Synthesis Saccharomyces cerevisiae Biology Peptide Mapping Biochemistry Protein Structure Secondary Nucleotide exchange factor Eukaryotic translation Transcription Initiation Factors Multienzyme Complexes Catalytic Domain Eukaryotic initiation factor Humans Initiation factor Peptide Chain Initiation Translational Molecular Biology Genetics Translation Regulation eIF2 Cell Biology EIF4A1 Eukaryotic translation initiation factor 4 gamma Protein Structure Tertiary Eukaryotic Initiation Factor-2B Protein Synthesis and Degradation Protein-Protein Interactions eIF2B biology.protein |
| Zdroj: | The Journal of Biological Chemistry |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m111.331645 |
| Popis: | Background: eIF2B is a critical translation factor and regulator of protein synthesis that is implicated in human disease. Results: Protein-protein interactions within the five-subunit eIF2B complex are identified. Conclusion: eIF2B complex formation requires extensive intersubunit domain interactions. Significance: The first experimental model is proposed for eIF2Bγ and -ϵ subunit interactions. In eukaryotic translation initiation, eIF2B is the guanine nucleotide exchange factor (GEF) required for reactivation of the G protein eIF2 between rounds of protein synthesis initiation. eIF2B is unusually complex with five subunits (α–ϵ) necessary for GEF activity and its control by phosphorylation of eIF2α. In addition, inherited mutations in eIF2B cause a fatal leukoencephalopathy. Here we describe experiments examining domains of eIF2Bγ and ϵ that both share sequence and predicted tertiary structure similarity with a family of phospho-hexose sugar nucleotide pyrophosphorylases. Firstly, using a genetic approach, we find no evidence to support a significant role for a potential nucleotide-binding region within the pyrophosphorylase-like domain (PLD) of eIF2Bϵ for nucleotide exchange. These findings are at odds with one mechanism for nucleotide exchange proposed previously. By using a series of constructs and a co-expression and precipitation strategy, we find that the eIF2Bϵ and -γ PLDs and a shared second domain predicted to form a left-handed β helix are all critical for interprotein interactions between eIF2B subunits necessary for eIF2B complex formation. We have identified extensive interactions between the PLDs and left-handed β helix domains that form the eIF2Bγϵ subcomplex and propose a model for domain interactions between eIF2B subunits. |
| Databáze: | OpenAIRE |
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