The central domain of Escherichia coli TyrR is responsible for hexamerization associated with tyrosine-mediated repression of gene expression

Abstract

TyrR from Escherichia coli regulates the expression of genes for aromatic amino acid uptake and biosynthesis. Its central ATP-hydrolyzing domain is similar to conserved domains of bacterial regulatory proteins that interact with RNA polymerase holoenzyme associated with the alternative sigma factor, σ 54. It is also related to the common module of the AAA+ superfamily of proteins that is involved in a wide range of cellular activities. We expressed and purified two TyrR central domain polypeptides. The fragment comprising residues 188-467, called TyrR-(188-467), was soluble and stable, in contrast to that corresponding to the conserved core from residues 193 to 433. TyrR-(188-467) bound ATP ..