The goal of this project is to elucidate basic mechanisms of eukaryotic translation initiation using structural and other biochemical methods. Eukaryotic translation initiation is highly regulated by elements of the untranslated regions of mRNAs, 5'UTR and 3'UTR, by the cellular concentration of initiation factors, by the action of regulatory proteins and by signaling pathways that are initiated by external messages or cellular events. Dysregulation of translation initiation by elevated levels of initiation factors is found in many forms of cancer. Thus, correcting for out-of-balance initiation with small molecule agents is a promising new route for cancer therapy. The proposed research is focused on the mechanisms by which the small ribosomal particle is recruited to mRNA, mediated by the initiation factors eIF4E, eIF4G and the regulatory phosphoprotein 4EBP-1. The second aspect is focused on scanning of the pre-initiation complex to the AUG initiation codon, aided by the interplay between the initiation factors eIF4A, eIF4G and eIF4H. The third topic is on elucidating processes by which the factors eIF1, eIF1A, eIF5 and eIF22 help recruiting the initiator Met-tRNAMet to the ribosome and warrant the correct placement. A significant aspect is to discover and characterize inhibitors of initiation with the goal of developing anti-cancer agents with broad specificity. The research will pursue three specific aims: 1. Define the regulation of eIF4E by tumor-suppressive proteins and small molecules 2. Structure of the eIF4G/eIF4A/eIF4H complex and approaches for inhibition 3. Control of start-codon selection by interactions of eIF5, eIF1, eIF1A and eIF2

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Using structural methods we will study mechanisms of eukaryotic translation initiation. We will investigate routes for inhibiting this process to develop novel anti-tumor agents. We also will study the complex of the scaffold protein eIF4G with the RNA helicase eIF4A and the interaction of factors eIF5, eIF1 and eIF1A, which support start codon recognition by interacting with eIF2.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Macromolecular Structure and Function C Study Section (MSFC)
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Knowlton, John R
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Harvard Medical School
Schools of Medicine
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Obayashi, Eiji; Luna, Rafael E; Nagata, Takashi et al. (2017) Molecular Landscape of the Ribosome Pre-initiation Complex during mRNA Scanning: Structural Role for eIF3c and Its Control by eIF5. Cell Rep 18:2651-2663
Salvi, Nicola; Papadopoulos, Evangelos; Blackledge, Martin et al. (2016) The Role of Dynamics and Allostery in the Inhibition of the eIF4E/eIF4G Translation Initiation Factor Complex. Angew Chem Int Ed Engl 55:7176-9
Leigh, Kendra E; Sharma, Mayuri; Mansueto, My Sam et al. (2015) Structure of a herpesvirus nuclear egress complex subunit reveals an interaction groove that is essential for viral replication. Proc Natl Acad Sci U S A 112:9010-5
Edmonds, Katherine A; Wagner, Gerhard (2015) (1)H, (13)C, and (15)N backbone and sidechain chemical shift assignments for the HEAT2 domain of human eIF4GI. Biomol NMR Assign 9:157-60
Sekiyama, Naotaka; Arthanari, Haribabu; Papadopoulos, Evangelos et al. (2015) Molecular mechanism of the dual activity of 4EGI-1: Dissociating eIF4G from eIF4E but stabilizing the binding of unphosphorylated 4E-BP1. Proc Natl Acad Sci U S A 112:E4036-45
Yi, Tingfang; Arthanari, Haribabu; Akabayov, Barak et al. (2015) eIF1A augments Ago2-mediated Dicer-independent miRNA biogenesis and RNA interference. Nat Commun 6:7194
Yi, Tingfang; Kabha, Eihab; Papadopoulos, Evangelos et al. (2014) 4EGI-1 targets breast cancer stem cells by selective inhibition of translation that persists in CSC maintenance, proliferation and metastasis. Oncotarget 5:6028-37
Mahalingam, Poornachandran; Takrouri, Khuloud; Chen, Ting et al. (2014) Synthesis of rigidified eIF4E/eIF4G inhibitor-1 (4EGI-1) mimetic and their in vitro characterization as inhibitors of protein-protein interaction. J Med Chem 57:5094-111
Yefidoff-Freedman, Revital; Chen, Ting; Sahoo, Rupam et al. (2014) 3-substituted indazoles as configurationally locked 4EGI-1 mimetics and inhibitors of the eIF4E/eIF4G interaction. Chembiochem 15:595-611
Luna, Rafael E; Akabayov, Sabine R; Ziarek, Joshua J et al. (2014) Examining weak protein-protein interactions in start codon recognition via NMR spectroscopy. FEBS J 281:1965-73

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