Duplication of secretion signal sequences is deleterious for the secretion of human interferon alpha 4 from Saccharomyces cerevisiae and Bacillus subtilis.

Tandem duplication of a mitochondrial import leader sequence has been shown to markedly increase the efficiency of translocation of chimaeric precursors across mitochondrial membranes to the mitochondrial matrix. The principle of leader sequence duplication was applied to the protein secretion system of the yeast Saccharomyces cerevisiae and of Bacillus subtilis. The secretion signal sequences of yeast invertase and B. subtilis neutral protease were used to direct the secretion of human interferon alpha 4. Our results show that the duplication of these N-terminal signal sequences does not enhance secretion of interferon alpha 4 in either of the cell systems studied.