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Protein-protein-interaction network organization of the hypusine modification system.

ABSTRACT: Hypusine modification of eukaryotic initiation factor 5A (eIF-5A) represents a unique and highly specific post-translational modification with regulatory functions in cancer, diabetes, and infectious diseases. However, the specific cellular pathways that are influenced by the hypusine modification remain largely unknown. To globally characterize eIF-5A and hypusine-dependent pathways, we used an approach that combines large-scale bioreactor cell culture with tandem affinity purification and mass spectrometry: "bioreactor-TAP-MS/MS." By applying this approach systematically to all four components of the hypusine modification system (eIF-5A1, eIF-5A2, DHS, and DOHH), we identified 248 interacting proteins as components of the cellular hypusine network, with diverse functions including regulation of translation, mRNA processing, DNA replication, and cell cycle regulation. Network analysis of this data set enabled us to provide a comprehensive overview of the protein-protein interaction landscape of the hypusine modification system. In addition, we validated the interaction of eIF-5A with some of the newly identified associated proteins in more detail. Our analysis has revealed numerous novel interactions, and thus provides a valuable resource for understanding how this crucial homeostatic signaling pathway affects different cellular functions.

SUBMITTER: Sievert H

PROVIDER: S-EPMC3494187 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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Protein-protein-interaction network organization of the hypusine modification system.

Sievert Henning H Venz Simone S Platas-Barradas Oscar O Dhople Vishnu M VM Schaletzky Martin M Nagel Claus-Henning CH Braig Melanie M Preukschas Michael M Pällmann Nora N Bokemeyer Carsten C Brümmendorf Tim H TH Pörtner Ralf R Walther Reinhard R Duncan Kent E KE Hauber Joachim J Balabanov Stefan S

Molecular & cellular proteomics : MCP 20120810 11

Hypusine modification of eukaryotic initiation factor 5A (eIF-5A) represents a unique and highly specific post-translational modification with regulatory functions in cancer, diabetes, and infectious diseases. However, the specific cellular pathways that are influenced by the hypusine modification remain largely unknown. To globally characterize eIF-5A and hypusine-dependent pathways, we used an approach that combines large-scale bioreactor cell culture with tandem affinity purification and mass ...[more]

PMID: 22888148

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Project description:Translation elongation factors facilitate protein synthesis by the ribosome. Previous studies identified two universally conserved translation elongation factors, EF-Tu in bacteria (known as eEF1A in eukaryotes) and EF-G (eEF2), which deliver aminoacyl-tRNAs to the ribosome and promote ribosomal translocation, respectively. The factor eIF5A (encoded by HYP2 and ANB1 in Saccharomyces cerevisiae), the sole protein in eukaryotes and archaea to contain the unusual amino acid hypusine (N(epsilon)-(4-amino-2-hydroxybutyl)lysine), was originally identified based on its ability to stimulate the yield (endpoint) of methionyl-puromycin synthesis-a model assay for first peptide bond synthesis thought to report on certain aspects of translation initiation. Hypusine is required for eIF5A to associate with ribosomes and to stimulate methionyl-puromycin synthesis. Because eIF5A did not stimulate earlier steps of translation initiation, and depletion of eIF5A in yeast only modestly impaired protein synthesis, it was proposed that eIF5A function was limited to stimulating synthesis of the first peptide bond or that eIF5A functioned on only a subset of cellular messenger RNAs. However, the precise cellular role of eIF5A is unknown, and the protein has also been linked to mRNA decay, including the nonsense-mediated mRNA decay pathway, and to nucleocytoplasmic transport. Here we use molecular genetic and biochemical studies to show that eIF5A promotes translation elongation. Depletion or inactivation of eIF5A in the yeast S. cerevisiae resulted in the accumulation of polysomes and an increase in ribosomal transit times. Addition of recombinant eIF5A from yeast, but not a derivative lacking hypusine, enhanced the rate of tripeptide synthesis in vitro. Moreover, inactivation of eIF5A mimicked the effects of the eEF2 inhibitor sordarin, indicating that eIF5A might function together with eEF2 to promote ribosomal translocation. Because eIF5A is a structural homologue of the bacterial protein EF-P, we propose that eIF5A/EF-P is a universally conserved translation elongation factor.

Dataset Information

Protein-protein-interaction network organization of the hypusine modification system.

Publications

Protein-protein-interaction network organization of the hypusine modification system.

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