Analysis of interaction of regulatory protein TyrR with DNA

Abstract

Publisher Summary This chapter describes the methodology used to characterize the linkage between the binding of ligands to TyrR and the interaction of TyrR with DNA. The experimental strategies, based primarily on the analysis of sedimentation behavior, provide a quantitative model for the role of tyrosine as a low molecular weight effector of the TyrR regulon. TyrR is a DNA-binding protein that regulates several genes involved in aromatic amino acid biosynthesis in Escherichia coli . Regulation occurs via the repression or activation of several unlinked operons that comprise the TyrR regulon. It discusses that repression varies considerably in magnitude between the different operons and usually involves the coeffectors ATP and tyrosine whereas activation is ATP independent and requires any of the three aromatic amino acids. Strong boxes bind TyrR strongly in vitro in the absence of coeffectors whereas weak boxes have less identity with the consensus sequence and do not bind TyrR unless there is an adjacent strong box and both ATP and tyrosine are present. In most operons repressed by tyrosine, overlap of the promoter by the operator is predominantly via the weak box.