Structure of a Fab Complex with the C-terminal fragment of merozoite surface protein-1 of Plasmodium vivax determined by Computational Docking

Issue title: II Congress of Theoretical and Computational Physical Chemistry, Choroni, Venezuela, 2008

Guest editors: H. Soscunxy, F. Ruettez and A. Sierraltaz

Article type: Research Article

Authors: Serrano, M.L.^{a; *} | Gauna, A.^b | Pérez, H.A.^c | Squitieri, E.^b | Medina, J.D.^d

Affiliations: [a] Unidad de Química Medicinal, Facultad de Farmacia, Universidad Central de Venezuela, Caracas 1041-A, Venezuela | [b] Escuela de Química, Facultad de Ciencias, Universidad Central de Venezuela, Apartado 47102, Caracas 1020-A, Venezuela | [c] Laboratorio de Inmunoparasitología, Centro de Microbiología y Biología Celular, IVIC, Apartado 21827, Caracas 1020-A, Venezuela | [d] Unidad de Productos Naturales, Facultad de Farmacia, Universidad Central de Venezuela, Caracas 1041-A, Venezuela | [x] Centro Nacional de Tecnologia Quimica CNTQ, Complejo Tecnologico Simon Rodriguez CTSR, La Carlota, Caracas, Venezuela | [y] Departamento de Quimica, Facultad Experimental de Ciencias, La Universidad del Zulia LUZ, Maracaibo, Venezuela | [z] Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas IVIC, Caracas, Venezuela

Correspondence: [*] Corresponding author: María Luisa Serrano; Unidad de Química Medicinal, Facultad de Farmacia, Universidad Central de Venezuela, Caracas, 1041-A, Venezuela. Tel.: +58 212 605 2697; Fax: +58 212 605 2707; E-mail: maria.serrano@ucv.ve.

Abstract: One current vaccine candidate against Plasmodium vivax, targeting asexual blood stages, is the major merozoite surface protein-1 of P. vivax (PvMSP-1). Vaccine trials with PvMSP-119 and PvMSP-133 have succeeded in protecting monkeys and it has been shown that a large proportion of individuals naturally exposed to P. vivax infection, develop specific antibodies to PvMSP-119. In the present study, computational protein-protein docking was used to predict the structure of the antigen--antibody complex between PvMSP119 and the Fab region of the G17.12 monoclonal antibody. This antibody does not inhibit erythrocyte invasion or MSP1 processing, but it recognises a discontinuous epitope on PfMSP119 that has been mapped to regions recognised by invasion-inhibiting antibodies. The molecular simulations were performed using, as starting structures, the Fab fragment of the P. falciparum MSP119-mAbG17.12 complex (pdb:1ob1) and the structure of the P. vivax MSP119 previously determined by homology modeling. The mAb was submitted to a docking procedure with antigen PvMSP119 using the programs PatchDock and FireDock to obtain an initial structure for the complex. A final optimization was performed with RosettaDock using a Monte Carlo algorithm. The final structure of the PvMP119-mAb17.12 complex shows that the antibody recognizes a discontinuous epitope that include segments on the first domain and some residues at the end of the second domain. The model provides valuable guidelines for future experimental work devoted to the identification of B-epitopes and synthesis of peptides with antigenic activity.

Keywords: Merozoite surface protein 1, Plasmodium vivax, malaria vaccine candidate, antibody–antigen complex, docking

DOI: 10.3233/JCM-2009-0309

Journal: Journal of Computational Methods in Sciences and Engineering, vol. 9, no. 4-6, pp. 353-361, 2009