SECRETION OF STREPTOKINASE FUSION PROTEINS FROM ESCHERICHIA-COLI-CELLS THROUGH THE HEMOLYSIN TRANSPORTER

The hemolysin (HlyA) secretion system was used to achieve the sec-inde pendent secretion of streptokinase (Skc) originating from Streptococcu s equisimilis into the medium by Escherichia coli cells. The in-frame fusions of the skc gene, either possessing or lacking a region encodin g the signal peptide (SP) with the 3'-end of the hlyA gene of various lengths were analysed. All hybrids retained Skc activity. Hybrid prote ins devoided of the N-terminal SP, regardless of length of the hlyA se cretion signal (62 vs. 194 amino acids), were secreted into the medium by the E. coli HlyA transporter at similar levels. Considerable amoun ts of hybrid proteins were still, however, associated with E. coli cel ls, mainly in the degraded form.