The C-terminal substrate binding domain of an uncharacterized LysR-type transcriptional regulator similar to regulators involved in the catabolism of aromatic compounds, contains type 2 periplasmic binding fold.
This CD represents the substrate binding domain of an uncharacterized LysR-type regulator similar to CbnR which is involved in the regulation of chlorocatechol breakdown. 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. 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.