Modulation of Bacillus subtilis alpha-amylase promoter activity by the presence of a palindromic sequence in front of the gene.

Upstream of the promoter of the Bacillus subtilis alpha-amylase gene (amyE) derived from an alpha-amylase hyper-producing strain, there is an inverted repeat sequence (palindromic sequence), which has a free energy of 21.2 kcal/mol due to the formation of stable stem-loop structure. The role of the palindromic sequence for the expression of amyE was studied using a plasmid encoding the amyE'-'bla (E. coli beta-lactamase) fused gene in an alpha-amylase-deficient B. subtilis mutant as the host. By the presence of the palindromic sequence, the transcription activity of the amyE promoter was enhanced approximately 6 fold by starch (3%) in the medium and was less repressed by glucose.