Synergism of regulatory elements in σ^B- and σ^A-dependent promoters enhances recombinant protein expression in Bacillus subtilis

Abstract

© 2015 The Society for Biotechnology, Japan. Strong promoter is an essential factor for production of recombinant protein in various expression systems including Bacillus subtilis. In this study, we described a strategy to improve the expression efficiency using synthetic double promoter. Assembly of the conserved elements from σB- and σA-dependent promoters constitutively improved the yield of recombinant protein approximately 2-3-fold in both exponential and stationary growth phase. The synergistic effect in the double promoter was observed only when σB-promoter was located upstream to σA-promoter but independent to its orientation. A conserved element in either -10 or -35 box of σB-promoter is sufficient to promote the synergism. Hence, this simple strategy of promoter engineering could be an effective way to generate a pool of strong constitutive promoters applicable for heterologous protein expression in B. subtilis in the future.