Title:Expression of Brazzein, a Small Sweet-Tasting Protein in Saccharomyces cerevisiae: An Introduction for Production of Sweet Yeasts
Volume: 27
Issue: 10
Author(s): Akram Kazemi-Nasab and Azar Shahpiri*
Affiliation:
- Department of Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111,Iran
Keywords:
Brazzein, E. coli, recombinant, Saccharomyces cerevisiae, solubility sweetness, glutathione-S-transferase.
Abstract:
Background: The replacement of carbohydrate sweeteners with protein sweeteners from
plants has attracted the interest of researchers because these proteins don’t trigger the insulin response
and are more nutritive for consumption in food. Brazzein (Braz) is a small and heat- stable
sweet protein that has been originally derived from African plant Pentadiplandra brazzeana. In the
present work the solubility, sweetness and yield of recombinant forms of Braz in two expression
hosts, E. coli and S. cerevisiae were comprised.
Methods: The codon-optimized gene of Braz was cloned in expression vectors pET28a and
pET41a and GPD. The resulted vectors pET28a-Braz and pEt41a-Braz were transformed into
Escherichia coli strain Rosetta (DE3) and the vector GPD-Braz was transformd to S. cerevisiae.
The expression of Braz in different systems was analyzed by SDS-PAGE and western blotting.
Results: The results verified the heterologous expression of Braz in S. cerevisiae carrying GPDBraz.
Also the expression of Braz as carboxy-terminal extensions of His-tag and Glutathione-STransferase
(GST) were verified in transgenic E. coli containing pET28a-Braz and pET41a-Braz,
respectively.
Conclusion: Although the yield of GST-Braz was higher than His-Braz and Braz expressed in S.
cerevisiae, but the higher solubility, sweetness, safety (GRAS) are important advantages of the use
of S. cerevisiae as expression host for production of Braz. Therefore the result of present work
opens new insights for providing the new sweet yeasts that can be used as food additives.
