DELETION ANALYSIS OF PROMOTER ELEMENTS OF THE ASPERGILLUS-ORYZAE AGDAENCODING ALPHA-GLUCOSIDASE

The nucleotide sequence of a 1.5-kb fragment of the promoter region of the Aspergillus oryzae agdA gene encoding alpha-glucosidase was deter mined. A comparison with the promoter regions of other Aspergillus amy lase genes indicated that there are three highly conserved sequences, designated Regions I, II and III, located at - 670 nt, - 596 nt and - 544 nt relative to the start codon, respectively. The function of thes e consensus sequences in the agdA promoter was investigated by deletio n analysis of a promoter fusion with the Escherichia coli uidA gene, u sing the niaD homologous-transformation system, Deletion of the upstre am half of Region III (IIIa; - 544 to - 529) resulted in a more than 9 0% reduction in GUS activity and abolished maltose induction, suggesti ng that Region IIIa is a functionally essential element for high-level expression and maltose induction, Deletion of Region I and the downst ream half of Region III (IIIb; - 521 to - 511) resulted in a significa nt reduction in GUS activity, but did not affect maltose induction, Th is suggested that these two elements most likely contain sequences inv olved in efficient expression in cooperation with Region IIIa. In addi tion, deletion of a 340-bp region between Region IIIb and the putative TATA bos resulted in a 2-fold increase in activity.