Expression and Secretion in S. Cerevisiae of Biologically Active Leech Hirudin

Hirudin synthesized by the medicinal leech Hirudo medicinalis is the most potent antithrombic factor found in nature. We have used Saccharomyces cerevisiae for the efficient production of recombinant hirudin variant 2 (rHV2). The mature hirudin coding sequence was placed in frame with the prepro sequence of the yeast MFα1 gene. Multicopy plasmids carrying different fused genes transcribed from the MFα1 promoter were used to transform a yeast strain selecting for uracil prototrophy. Analysis of proteins from culture supernatants revealed efficient secretion of hirudin in all cases. However, only precursors in which the HV2 mature sequence directly followed the cleavage site for yscF (a protease involved in the maturation of yeast α factor) were processed correctly to yield biologically active hirudin.