FUNCTIONAL EXPRESSION OF TX1 FROM THE BRAZILIAN “ARMED” SPIDER Phoneutria nigriventer, A Ca⁺⁺ CHANNEL BLOCKER

Diniz, M.R.V., Theakston, R.D.G., de Assis, J.B., Crampton, J.M., Diniz C.R., de Lima M.E. 

Centro de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte, MG, Brazil

The Tx1 from the venom of the Brazilian spider Phoneutria nigriventer, a lethal neurotoxic polypeptide of Mr 8kDa with fourteen cysteine residues, selectively inhibits voltage sensitive calcium channels from GH3 cells. The cDNA gene encoding this toxin was previously isolated and identified (Diniz et al. (1993) J. Biol. Chem. 268, 15340-15342). The coding region for matured toxin was amplified, cloned and expressed as thioredoxin fusion product in cytoplasm of Escherichia coli. After affinity purification and cleavage, the recombinant TX-1 displayed the same properties as the native toxin in its chromatographical behaviour, convulsive-inducing biological activity, immunological reactivity towards the antibodies raised against the toxin and binding to receptors in rat brain synaptosomes.

Supported by: FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais).

CORRESPONDENCE TO:

DINIZ, M.R.V., Centro de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Rua Conde Pereira Carneiro, 80. 30510-010, Belo Horizonte (MG), Brazil, Email: mdiniz@funed.mg.gov.br