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Modeling the interaction between aldolase and the thrombospondin-related anonymous protein, a key connection of the malaria parasite invasion machinery

Authors

  • Carlos A. Buscaglia,

    Corresponding author
    1. Michael Heidelberg Division of Pathology of Infectious Diseases, Department of Pathology, New York University School of Medicine (NYSoM), New York
    • Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de General San Martín-CONICET; Av. Gral Paz y Albarellos, Predio INTI, edificio 24, San Martín (1650), Buenos Aires, Argentina
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  • Wim G. J. Hol,

    1. Department of Biochemistry, Howard Hughes Medical Institute, Biomolecular Structure Center, University of Washington, Seattle, Washington
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  • Victor Nussenzweig,

    1. Michael Heidelberg Division of Pathology of Infectious Diseases, Department of Pathology, New York University School of Medicine (NYSoM), New York
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  • Timothy Cardozo

    1. Department of Pharmacology, New York University School of Medicine (NYSoM), New York
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Abstract

A complex molecular motor empowers substrate-dependent motility and host cell invasion in malaria parasites. The interaction between aldolase and the transmembrane adhesin thrombospondin-related anonymous protein (TRAP) transduces the motor force across the parasite surface. Here, we analyzed this interaction by using state-of-the-art flexible docking. Besides algorithms to account for induced fit in the side-chains of the Plasmodium falciparum aldolase (PfAldo) structure, we used additional in silico receptors modeled upon crystallographic structures of evolutionarily related aldolases to incorporate enzyme backbone flexibility, and to overcome structure inaccuracies due to the relatively low resolution (3.0 Å) of the genuine PfAldo structure. Our results indicate that, in spite of multiple intermolecular contacts, only the six C-terminal residues of the TRAP cytoplasmic tail bind in an ordered manner to PfAldo. This portion of TRAP targets the PfAldo active site, with its n-1 Trp residue, which is essential for this interaction, buried within the PfAldo catalytic pocket. Docking of a TRAP peptide bearing a Trp to Ala mutation rendered the lower energy configurations either bound weakly outside the active site or not bound to PfAldo at all. The position of the bound TRAP peptide, and particularly the close proximity between the carbonyl of its n-2 Asp residue and the experimentally determined position of the phosphate-6 group of fructose 1,6-phosphate bound to mammalian aldolases, predicts an inhibitory effect of TRAP on catalysis. Enzymatic and TRAP-binding assays using mutant PfAldo molecules strongly support the overall structural model. These results might provide the initial framework for the identification of novel antiparasitic compounds. Proteins 2007. © 2006 Wiley-Liss, Inc.

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