ABSTRACT
Foreign genes can be inserted into the vector such that the DNA encoding the mature region of the secretory protein is fused directly to the 3' end of the MWP signal sequence. The frequency of transformation varied up to 10 transformants per 1 fig of plasmid DNA, depending on the kinds of plasmids and host strains. Production of large amounts of some animal proteins (more than 0.5 g/L) has been reported in other systems, such as Pichiapastoris. Another interesting feature of this chapter is to elucidate the secretory pathway of animal proteins in bacteria. That B. brevis secretes epidermal growth factor in extraordinary high yield indicates that bacterial secretory machinery can function quite well in translocating newly formed animal polypeptides into the external medium. Analysis of hypersecretory mutants as well as those protein-folding enzymes, including “chaperon-in,” should provide important information for further improvements in the system.
