[Preparation of Saccharomyces cerevisiae strains with regulated MFalpha1 promotor activity]

Two Saccharomyces cerevisiae strains containing integrated copies of the MAT alpha 1 gene fused to the PHO5 promoter have been obtained by transformation of a MAT alpha 1 mutant. The strains differ in length of 5'-uncoding region of the MAT alpha 1 in the integrated constructions. The mating activity and the ability of these strains to express the yeast MF alpha 1 gene and the hyman alpha-N-interferon gene under the control of MF alpha 1 promoter was shown to be regulated by the exogenous inorganic phosphate. The level of intracellular alpha-N-interferon synthesized in these strains was several fold higher as compared with the wild type alpha mating type strain. At the same time the observed increase in intracellular production is not accompanied by an increase in the level of secreted alpha-N-interferon. On the contrary, one of the strains had a two-fold reduction in the rate of secretion.