Signal peptide of Arabinosidase enhances secretion of interferon-α2b protein by Bifidobacteria longum

Bifidobacteria can potentially be used for gene therapy. Here, we reported that 65% of the total hIFN-α2b produced from Bifidobacteria longum transformed with pBAD-SPIFN plasmids encoding a fusion protein of the arabinosidase signal peptide and human IFN-α2b (hIFN-α2b), was secreted. For B. longum transformed with pBAD-IFN plasmids (hIFN-α2b without the signal peptide), only 15% of the total IFN-α2b was secreted and western blotting and N-terminal amino-acid sequence analysis revealed cleavage of the arabinosidase signal peptide from the secreted hIFN-α2b. Moreover, the active level of the secreted hIFN-α2b in the supernatant of B. longum transformed with pBAD-SPIFN plasmids was over 1,000 IU/ml commercial rhIFN-α2b. Hence, the arabinosidase signal peptide can enhance the secretion efficiency of IFN-α2b from B. longum.