FUNCTIONAL EXPRESSION OF TOXINS FROM THE BRAZILIAN “ARMED” SPIDER Phoneutria nigriventer IN Escherichia coli

DINIZ, M.R.V.(1)

(1)From The Centro de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Rua Conde Pereira Carneiro, 80, CEP 30510-010, Belo Horizonte, MG, Brazil

The venomous glands of the Brazilian spider Phoneutria nigriventer produce a complex mixture of basic neurotoxic dissulfide-rich polypeptide ranging in size from 2-16 Kda They are associated with distinct effect of the venom. The molecular characterization of the precursor sequence of theses toxins have been performed by integrating information generated from a molecular genetic approach using cDNAs with data provided from primary sequence of native toxins. The likely mechanisms by which the toxins precursors peptides are processed to their mature forms have been deduced. A particularly interesting feature of the prepropeptides are the occurrence of the glutamate rich sequence interposed between the signal sequence and mature toxin peptide. Excision of the functional toxin appears to be signalled by flanking arginine residue and probably occurs only after the dissuphides linkages have been formed. The cDNA coding region for matured toxin of Tx1 and Tx3-2 have been amplified, cloned and expressed as thioredoxin fusion product in cytoplasm of Escherichia coli. After affinity purification and cleavage, the recombinant toxins displayed the same properties as the native toxins at least in their neurotoxic biological activity after intracerebral ventricular injection.

This research was 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, CEP 30510-010, Belo Horizonte, MG, Brazil, Email: mdiniz@funed.mg.gov.br