Dual transcriptional regulator of the TyrR regulon, which includes a number of genes coding for proteins involved in the biosynthesis or transport of the three aromatic amino acids, phenylalanine, tyrosine and tryptophan. These three aromatic amino acids act as effectors which bind to the TyrR protein to form an active regulatory protein. Acts by binding specifically to TyrR boxes in the promoter region of the target genes. Homodimer. In presence of tyrosine (or high concentrations of phenylalanine or tryptophan) and ATP, it self-associates to form an hexamer.