HETEROLOGOUS GENE EXPRESSION IN LACTOCOCCUS, AND THE EXPRESSION PRODUCTS THEREFROM

摘要

Heterologous polypeptides are produced in Lactococcus by means of a T7 or T7-like RNA polymerase gene placed under the control of an inducible promoter effective in the Lactococcal host, and a promoter specific for said polymerase upstream of a coding sequence for the desired polypeptide, whereby the promoter directs transcription of said coding sequence selectively as a result of expression of said polymerase. Surprisingly, the Gram-negative E. coli derived T7 RNA polymerase system works extremely well in the Gram-positive Lactococcus host. The heterologous polypeptide can be produced in high yields (e.g. 22%) as soluble intracellular protein, or can be secreted, e.g. at a rate commensurate with its expression so that only low levels or zero amount of polypeptide is accumulated intracellularly. The polypeptide within the cell, being biologically active, can be delivered in that encapsulated form, e.g. as a parenteral, topical or oral medicament or vaccine, or as an environmental pesticide. Examples of expression product are TTFC, the HIV V3 loop and B. thuringiensis toxins.