MFalpha signal peptide enhances the expression of cellulase eg1 gene in yeast.

Ethanol production from lignocellulose by recombinant yeast with high level expression of heterologous cellulase genes has been a major anticipation. The native secretion signal sequence of the cellulase endoglucanase I (eg1) gene was replaced by Saccharomyces cerevisiae mating factor alpha prepro-leader sequence (MFalpha). The transformants containing native secretion signal (Y(1)) and MFalpha secretion signal (Y(2)) were characterized with respect to gene expression and growth on cellulose substrate. Increased enzyme activity and cellulose utilization were observed. The enzyme activity of Y(2) was 0.084 U/ml, 61.5% higher than Y(1) (0.052 U/ml). The sufficiency parameter (S value) was raised from 0.6 to 0.84. MFalpha signal peptide was more efficient than the native signal peptide of eg1 gene, suggesting that signal peptide replacement is an efficient way to enhance the cellulase expression level in yeast, for cellulose-derived ethanol production.