IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Modelado y predicción de los epitopes del antigeno P22 de Toxoplasma gondii
Autor/es:
COSTA, JUAN GABRIEL; FACCENDINI, PABLO LUIS; LAGIER, CLAUDIA MARINA; MARCIPAR, IVÁN SERGIO
Lugar:
Córdoba
Reunión:
Congreso; 2do Congreso de Bioinformática y Biología Computacional; 2011
Institución organizadora:
Asociación Argentina de Bioinformática y Biología Computacional
Resumen:
Modelling and epitope prediction of Toxoplasma gondii P22 antigen Juan Gabriel Costa 1, Pablo Faccendini 2, Claudia Marina Lagier 2, Iván Sergio Marcipar 1 1 Laboratorio de Tecnología Inmunológica, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina 2IQUIR-CONICET, Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina Background: P22 is a membrane protein from Toxoplasma gondii which has been proposed as a useful diagnostic tool to assess specific antibodies in acute toxoplasmosis. The identification of its antigenic regions would allow the rational design of vaccines and antigens to be used in immunochemical assays. Experimental approaches are time consuming, expensive and they may lead to not reliable results. Therefore, to identify the above mentioned regions we have modeled the 3D structure and we have used the model to predict conformational and continuous B epitopes. Methods and Results: The model was obtained by homology modelling using Modeller software. We used the X-ray crystallographic structure from sporoSAG protein as template. This molecule is expressed in T. gondii and although it has low identity with P22 antigen (29%), it is evolutionarily related to P22 [1]. Several models were obtained and the best was selected based on online software tests: Verify3D (http://nihserver.mbi.ucla.edu/Verify_3D/) and ANOLEA (http://protein.bio.puc.cl/cardex/servers/anolea/index.html). We considered as evaluation criterion, the aminoacid ratio which overcome the 0,15 value from the internal score of Verify3D, and display ANOLEA values below 0 E/kT. The model which had the best ratio in both analyses was selected. The refined model shown in Figure 1 was obtained using UCSF Chimera software and LOBO (online: http://protein.cribi.unipd.it/lobo/). Figure 1: Refined model of P22 protein Conformational B epitopes were predicted using Discotope online software (http://www.cbs.dtu.dk/services/DiscoTope/), based on the 3D structure obtained. The best antigenic performance were predicted for residues corresponding to positions 34 to 40, 52, 63, 65, 66, 69, 77, 80, 83 a 86, 95, 96, 98, 162, 163, 165, 166, 169 y 182 to 186. Continous B epitopes were also assessed using online AAPPred software (http://www.bioinf.ru/aappred/), the main antigenic regions being predicted between residues 30 to 45, 93 to 99 and 115 to 145. Conclusion: We have predicted the tridimensional structure of T. gondii acute phase protein P22 and the putatives epitopes by using free softwares. The bioinformatics approach showed to provide a valuable source of information which complements the experimental results. References: 1. Crawford J, Lamb E, Wasmuth J, Grujic O, Grigg M, Boulanger M. Structural and functional characterization of SporoSAG: a SAG2-related surface antigen from Toxoplasma gondii. J.Biol.Chem. 2010, 285: 12063-12070