In vivo and in vitro analyses of the AmyR binding site of the Aspergillus nidulans agdA promoter; Requirement of the CGG direct repeat for induction and high affinity binding of AmyR

The alpha -glucosidase gene (agdA) of Aspergillus nidulans has a single CGG N(8)CGG type AmyR binding site in its promoter region. The binding site is functional in vivo as a cis-element responsible for induction by starch, an d mutational studies indicated that both the CGG triplets are required for high-level induction. A part of AmyR (residues 1-411; AmyR(1-411)), which was produced as a MalE fusion protein in E. coli, bound to the CGGN(8)CGG site of the agdA promote r. DNA binding profiles to the mutant binding sites that lacked both or eit her one of the CGG triplets suggested that AmyR(1-411) can bind to a single CGG triplet site with low affinity and that two AmyR molecules cooperative ly bind to the CGG direct repeat.