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Singh CR, Watanabe R, Zhou D, Jennings MD, Fukao A, Lee B, Ikeda Y, Chiorini JA, Campbell SG, Ashe MP, Fujiwara T, Wek RC, Pavitt GD, Asano K. Mechanisms of translational regulation by a human eIF5-mimic protein. Nucleic Acids Res 2011; 39:8314-28. [PMID: 21745818 PMCID: PMC3201852 DOI: 10.1093/nar/gkr339] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/22/2011] [Accepted: 04/25/2011] [Indexed: 11/29/2022] Open
Abstract
The translation factor eIF5 is an important partner of eIF2, directly modulating its function in several critical steps. First, eIF5 binds eIF2/GTP/Met-tRNA(i)(Met) ternary complex (TC), promoting its recruitment to 40S ribosomal subunits. Secondly, its GTPase activating function promotes eIF2 dissociation for ribosomal subunit joining. Finally, eIF5 GDP dissociation inhibition (GDI) activity can antagonize eIF2 reactivation by competing with the eIF2 guanine exchange factor (GEF), eIF2B. The C-terminal domain (CTD) of eIF5, a W2-type HEAT domain, mediates its interaction with eIF2. Here, we characterize a related human protein containing MA3- and W2-type HEAT domains, previously termed BZW2 and renamed here as eIF5-mimic protein 1 (5MP1). Human 5MP1 interacts with eIF2 and eIF3 and inhibits general and gene-specific translation in mammalian systems. We further test whether 5MP1 is a mimic or competitor of the GEF catalytic subunit eIF2Bε or eIF5, using yeast as a model. Our results suggest that 5MP1 interacts with yeast eIF2 and promotes TC formation, but inhibits TC binding to the ribosome. Moreover, 5MP1 is not a GEF but a weak GDI for yeast eIF2. We propose that 5MP1 is a partial mimic and competitor of eIF5, interfering with the key steps by which eIF5 regulates eIF2 function.
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Affiliation(s)
- Chingakham Ranjit Singh
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Ryosuke Watanabe
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Donghui Zhou
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Martin D. Jennings
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Akira Fukao
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Bumjun Lee
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Yuka Ikeda
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - John A. Chiorini
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Susan G. Campbell
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Mark P. Ashe
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Toshinobu Fujiwara
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Ronald C. Wek
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Graham D. Pavitt
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Katsura Asano
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
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Singh CR, Udagawa T, Lee B, Wassink S, He H, Yamamoto Y, Anderson JT, Pavitt GD, Asano K. Change in nutritional status modulates the abundance of critical pre-initiation intermediate complexes during translation initiation in vivo. J Mol Biol 2007; 370:315-30. [PMID: 17512538 PMCID: PMC2041914 DOI: 10.1016/j.jmb.2007.04.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 04/06/2007] [Accepted: 04/10/2007] [Indexed: 10/23/2022]
Abstract
In eukaryotic translation initiation, eIF2GTP-Met-tRNA(i)(Met) ternary complex (TC) interacts with eIF3-eIF1-eIF5 complex to form the multifactor complex (MFC), while eIF2GDP associates with eIF2B for guanine nucleotide exchange. Gcn2p phosphorylates eIF2 to inhibit eIF2B. Here we evaluate the abundance of eIFs and their pre-initiation intermediate complexes in gcn2 deletion mutant grown under different conditions. We show that ribosomes are three times as abundant as eIF1, eIF2 and eIF5, while eIF3 is half as abundant as the latter three and hence, the limiting component in MFC formation. By quantitative immunoprecipitation, we estimate that approximately 15% of the cellular eIF2 is found in TC during rapid growth in a complex rich medium. Most of the TC is found in MFC, and important, approximately 40% of the total eIF2 is associated with eIF5 but lacks tRNA(i)(Met). When the gcn2Delta mutant grows less rapidly in a defined complete medium, TC abundance increases threefold without altering the abundance of each individual factor. Interestingly, the TC increase is suppressed by eIF5 overexpression and Gcn2p expression. Thus, eIF2B-catalyzed TC formation appears to be fine-tuned by eIF2 phosphorylation and the novel eIF2/eIF5 complex lacking tRNA(i)(Met).
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Affiliation(s)
- Chingakham Ranjit Singh
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Tsuyoshi Udagawa
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Bumjun Lee
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Sarah Wassink
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
| | - Hui He
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Yasufumi Yamamoto
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - James T. Anderson
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
| | - Graham D. Pavitt
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Katsura Asano
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
- Corresponding author: Katsura Asano, e-mail address,
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