Expression of a membrane-bound form of Trypanosoma cruzi trans-sialidase in baculovirus-infected insect cells: a potential tool for sialylation of glycoproteins produced in the baculovirus-insect cells system

A chimeric protein containing the catalytic domain of Trypanosoma cruzi tra ns-sialidase, the transmembrane domain of the major envelope glycoprotein o f the baculovirus (gp67), and the signal peptide of ecdysteroid glucosyltra nsferase of the baculovirus was expressed under the control of the very lat e promoter p10 in baculovirus-infected lepidopteran cells. The recombinant protein was found to be enzymatically active. Three days after infection, e qual amounts of activity were found associated to the plasma membrane and i n the infection medium, both forms having the same apparent molecular weigh t and being N-glycosylated. When exogenous galactosylated accepters (lactos e or asialo-alpha1-acid glycoprotein) were added in the culture medium of c ells infected with the recombinant baculovirus in the presence of a sialyla ted donor, a sialylation could be observed. Therefore, we propose the use o f trans-sialidase as a potential tool for sialylation of glycoconjugates in the baculovirus-insect cells system.