The C-terminal substrate binding domain of LysR-type transcriptional regulators that involved in the catabolism of nitroaromatic/naphthalene compounds and that of related regulators; contains the type 2 periplasmic binding fold.
This CD includes the C-terminal substrate binding domain of LysR-type transcriptional regulators involved in the catabolism of dinitrotoluene and similar compounds, such as DntR, NahR, and LinR. The transcription of the genes encoding enzymes involved in such degradation is regulated and expression of these enzymes is enhanced by inducers, which are either an intermediate in the metabolic pathway or compounds to be degraded. Also included are related LysR-type regulators clustered together in phylogenetic trees, including NodD, ToxR, LeuO, SyrM, TdcA, and PnbR. This substrate-binding domain shows significant homology to the type 2 periplasmic binding proteins (PBP2), which are responsible for the uptake of a variety of substrates such as phosphate, sulfate, polysaccharides, lysine/arginine/ornithine, and histidine. The PBP2 bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap. After binding their specific ligand with high affinity, they can interact with a cognate membrane transport complex comprised of two integral membrane domains and two cytoplasmically located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.