Heterotypic Sam–Sam Association between Odin-Sam1 and Arap3-Sam: Binding Affinity and Structural Insights

Authors

  • Flavia A. Mercurio,

    1. Department of Biological Sciences, University of Naples “Federico II”, Via Mezzocannone 16, 80134 Naples (Italy)
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  • Dr. Daniela Marasco,

    1. Department of Biological Sciences, University of Naples “Federico II”, Via Mezzocannone 16, 80134 Naples (Italy)
    2. Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, 80134 Naples (Italy)
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  • Dr. Luciano Pirone,

    1. Institute of Crystallography, National Research Council, Via Giovanni Amendola 122/O, 70126 Bari (Italy)
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  • Dr. Pasqualina L. Scognamiglio,

    1. Department of Biological Sciences, University of Naples “Federico II”, Via Mezzocannone 16, 80134 Naples (Italy)
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  • Dr. Emilia M. Pedone,

    1. Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, 80134 Naples (Italy)
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  • Prof. Maurizio Pellecchia,

    1. Infectious Diseases and Cancer Center, Sanford–Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037 (USA)
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  • Dr. Marilisa Leone

    Corresponding author
    1. Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, 80134 Naples (Italy)
    • Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, 80134 Naples (Italy)
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Abstract

Arap3 is a phosphatidylinositol 3 kinase effector protein that plays a role as GTPase activator (GAP) for Arf6 and RhoA. Arap3 contains a sterile alpha motif (Sam) domain that has high sequence homology with the Sam domain of the EphA2-receptor (EphA2-Sam). Both Arap3-Sam and EphA2-Sam are able to associate with the Sam domain of the lipid phosphatase Ship2 (Ship2-Sam). Recently, we reported a novel interaction between the first Sam domain of Odin (Odin-Sam1), a protein belonging to the ANKS (ANKyrin repeat and Sam domain containing) family, and EphA2-Sam. In our latest work, we applied NMR spectroscopy, surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) to characterize the association between Arap3-Sam and Odin-Sam1. We show that these two Sam domains interact with low micromolar affinity. Moreover, by means of molecular docking techniques, supported by NMR data, we demonstrate that Odin-Sam1 and Arap3-Sam might bind with a topology that is common to several Sam-Sam complexes. The revealed structural details form the basis for the design of potential peptide antagonists that could be used as chemical tools to investigate functional aspects related to heterotypic Arap3-Sam associations.

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