Insertion analysis of putative functional elements in the promoter region of the Aspergillus oryzae Taka-amylase A gene (amyB) using a heterologous Aspergillus nidulans amdS-lacZ fusion gene system

Expression of the Taka-amylase A gene (amyB) of Aspergillus oryzae is induc ed by starch or maltose. The A. oryzae amyB gene promoter contains three hi ghly conserved sequences, designated Regions I, II, and III, compared with promoter regions of the A. oryzae glaA encoding glucoamylase and the agdA e ncoding alpha-glucosidase. To identify the function of these sequences with in the amyB promoter, various fragments containing conserved sequences in t he amyB promoter were introduced into the upstream region of the heterologo us A. nidulans amdS gene (encoding acetamidase) fused to the Escherichia co li lacZ gene as a reporter. Introduction of the sequence between -290 to -2 33 (the number indicates the distance in base pairs from the translation in itiation point(+1)) containing Region III significantly increased the expre ssion of the lacZ reporter gene in the presence of maltose. The sequence be tween -377 to -290 containing Region I also increased the lacZ activity, bu t its maltose inducibility was less than that of Region III. The sequence b etween -233 to -181 containing Region II had no effect on the expression. T hese results indicated that Region III is most likely involved in the malto se induction of the amyB gene expression.