Expression of the MuIFN alpha 7 gene in Bacillus subtilis using the levansucrase system

The mouse interferon alpha 7 gene, the signal sequence of which has been removed by oligonucleotide-directed mutagenesis, was introduced into a Bacillus subtilis secretion vector containing the promoter and the signal sequence of the B. subtilis levansucrase gene. Different B. subtilis strains were transformed with the fused levansucrase-interferon gene; their cell extracts and culture supernatants tested for antiviral activity and the IFN alpha 7 protein showed the presence of IFN alpha 7 only in the cell extracts. To promote IFN alpha 7 secretion, constructs were realized in order to restore the alpha helix conformation of the signal sequence of levansucrase and interferon protein junction. Our results suggest that factors other than the structure of the peptide around the cleavage site are involved in the secretion of IFN alpha 7 by B. subtilis.