High level of expression of the Toxoplasma gondii-recombinant Rop2 protein in Escherichia coli as a soluble form for optimal use in diagnosis

NIGRO M, MARTIN V, KAUFER F, CARRAL L, ANGEL SO, PSZENNY V

MOLECULAR BIOTECHNOLOGY

HUMANA PRESS INC

Lugar: Oregon; Año: 2001 vol. 18 p. 269 - 273

1073-6085

The rhoptry 2 protein (Rop2) is an interesting protein of Toxoplasma gondii that is involved in the parasite invasion of host cell, it has three T-cell epitopes and high antigenic value. However, the expression of Rop2 as a recombinant protein in Escherichia coli is not an easy task, showing low levels of expression or degradation and solubility problems. Using a recombinant Rop2196–561 fused to 6 histidine residues, we showed high levels of expression in bacteria growing in terrific broth. rRop2196–561 was purified mainly as a soluble product and in high concentrations (approx 1 mg/mL) under native conditions (40 mM imidazol in phosphate buffer). However, after a cycle of freezing-thawing rRop2196–561 became insoluble. When glycerol was added to 26%, immediately after purification, the protein stayed soluble after cycles of freezing-thawing. Finally, it was demonstrated that under these conditions soluble rRop2196–561 keeps its diagnostic value in contrast with the insoluble protein.