title: Interaction of the eukaryotic initiation factor 4E with 4E-BP2 at a dynamic bipartite interface.
abstract: Cap-dependent translation initiation is regulated by the interaction of eukaryotic initiation factor 4E (eIF4E) with eIF4E binding proteins (4E-BPs). Whereas the binding of 4E-BP peptides containing the eIF4E-binding ⁵⁴YXXXXLΦ⁶⁰ motif has been studied, atomic-level characterization of the interaction of eIF4E with full-length 4E-BPs has been lacking. Here, we use isothermal titration calorimetry and nuclear magnetic resonance spectroscopy to characterize the dynamic, structural and binding properties of 4E-BP2. Although disordered, 4E-BP2 contains significant fluctuating secondary structure and binds eIF4E at an extensive bipartite interface including the canonical ⁵⁴YXXXXLΦ⁶⁰ and ⁷⁸IPGVT⁸² sites. Each of the two binding elements individually has submicromolar affinity and exchange on and off of the eIF4E surface within the context of the overall nanomolar complex. This dynamic interaction facilitates exposure of regulatory phosphorylation sites within the complex. The 4E-BP2 interface on eIF4E overlaps yet is more extensive than the eIF4G:eIF4E interface, suggesting that these key interactions may be differentially targeted for therapeutics.
authors.affiliation: Molecular Structure and Function Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
authors.forename: Sabelo
authors.initials: S
authors.lastname: Lukhele
authors.forename: Alaji
authors.initials: A
authors.lastname: Bah
authors.forename: Hong
authors.initials: H
authors.lastname: Lin
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.forename: Julie D
authors.initials: JD
authors.lastname: Forman-Kay
mesh_terms: D000494:Allosteric Regulation; D001665:Binding Sites; D039561:Eukaryotic Initiation Factor-4E / Q000737:chemistry*; D039603:Eukaryotic Initiation Factor-4G / Q000737:chemistry; D039642:Eukaryotic Initiation Factors / Q000737:chemistry*; D006801:Humans; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D011487:Protein Conformation
chemical_list: C104151:EIF4EBP2 protein, human; D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D039642:Eukaryotic Initiation Factors