Clonagem e expressão do cDNA codificante para a toxina do veneno de Lasiodora sp, LTx2, em vetor de expressão pET11a.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The venom from snakes, scorpions, spiders and other venomous animals is a very rich source of potent toxins. An interesting feature of some toxins is their remarkable species specificity. In the present work we cloned a sequence which codifies for the toxin LTx2 from the venom of the spider Lasiodora sp, in the expression vector pET11a. This toxin was previously identified in the screening of the cDNA library of the total venom. This toxin, when submitted to the local alignment tool, BLAST, shown similarity with the toxins huwetoxina-II and huwetoxina-VII, from the venom of the spider Selenocosmia huwena, as well as with the toxins LTx1 and LTx3 from Lasiodora sp. venom. After cloning in expression vector we verified if the fragment was inserted in the correct frame using the Sanger DNA sequencing method. The expression of the target protein was made by adding 0,6 mM IPTG to the media followed by a 3 to 4 hours incubation. With the assistance of immunochemical assays, we were able to detect that the target protein was been expressed in the form of inclusion bodies. Then we defined a strategy to recover the soluble refolded protein. Using a solution containing 6 M urea we proceed the solubilization of the inclusion bodies. The refolding of the soluble protein was made by the dialysis method in refolding buffer. The sample was, then, submitted to high pressure liquid chromatography, in a reversed phase column, to purify the protein. The purifying process was efficient, as shown by the Western Blotting and electrophoresis results. After that, we made an anti microbial assay, where we could see that the target protein, in the concentration of 400 mg/mL, inhibited the growth of the organisms used in the test. The expression and recovery of larger amounts of the target protein will allow tests with this toxin in other organisms and electrophysiological experiments.

ASSUNTO(S)

toxina biologia molecular clonagem biologia molecular

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