Critical Role of Alanine-161 in Delila Protein Involved in Regulation of Anthocyanin Pigmentation for Transcriptional Activation in Yeast

Abstract

Delila protein is a member of MYC-like transcriptional activator family, which regulates the expression of structural genes in the biosynthesis of anthocyanin in snapdragon. We have mutated several amino acid of Delila to elucidate their function using transcriptional activation by yeast one-hybrid system. Among several site-directed mutations, the replacement of alanine-161 with 18 different amino acids resulted in severe decrease in the transcriptional activation of the yeast GAL1 promoter Delila fused to the yeast GAL4 DNA-binding domain. This lack of induction indicates the importance of alanine-161 for transcriptional activation by Delila protein. Although the mutational change at residue 161 from alanine to aspartic acid exhibited no activity, the deletion of N-terminus (1-136 amino acids) of this mutant resulted in the recovery of activity. These results suggest that alanine-161 located outside the activation domain in Delila plays a critical role for its transcriptional activation in yeast.