neurotoxin-like protein from the Triatoma infestans kissing bug Salivary Gland

Correa, P.S.(1), D´Souza-Ault, M.(1), Martins, N.F.(2), Feijó, G.(1), Santana, J.M.(1), Lozzi, S.P.(1), Teixeira, A.R.L.(1)

(1)Laboratório Multidisciplinar de Pesquisa em Doença de Chagas, Universidade de Brasília, (2)Laboratório de Bioinformática, EMBRAPA, Recursos Genéticos e Biotecnologia, Brasília, DF, Brasil.

Introduction: Salivary proteins from several blood-sucking arthropods have revealed an unusual evolutionary relationship. Most induce vasodilation, inhibit blood coagulation, and reduce inflammation by different mechanisms (Montfort et al, 2000). Recently, it was found a Triatominea salivary protein with cytolytic and pore-forming activity (Amino et al, 2002). Our goal is to study the relationship between structure and function of these toxins. For this purpose the saliva from T. infestans, the major vector of Chagas disease, was submitted to a molecular screaning to identify pharmacological properties. This work presents study on the biology, biochemistry, molecular biology and modeling of a new cytolytic salivary gland protein. Methodology: The T. infestans salivary gland cDNA library that was constructed,was screened to select the clones.  Twenty clones were analysed. The most functional clone was selected for heterologous expression in insect cells and E. coli. The sequences were submitted to several bioinformatics analysis and molecular modeling procedures. Results and conclusions: the sequence analysis using BLAST and FASTA indicated 88% similarity with a neurotoxin from the scorpion Buthus occitanus. Its secondary structure was predicted using the TITO server and PROSPECT program and a proper template was found. The three dimensional structure was built using MODELLER 4.0. A theoretical model that was validated by PROCHECK and PROSAII programs, revealed a globular protein mainly with alpha-helix . The BLOCKS+ search revealed a phosphatase domain in the protein core. Active site prediction showed a possible binding cavity for the substrate docking.

CORRESPONDENCE TO:

Patrícia Spoto Corrêa, SQN 206 Bl. B apt.602, Brasília, DF, CEP: 70844-020, Brasil, Email: pcorrea@unb.br