The C-terminal substrate biniding domain of an uncharacterized LysR-like transcriptional regulator Pa0477 related to DntR, contains the type 2 periplasmic binding fold.
LysR-type transcriptional regulator Pa0477 is related to DntR, which controls genes encoding enzymes for oxidative degradation of the nitro-aromatic compound 2,4-dinitrotoluene. 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. The topology of this substrate-binding domain is most similar to that of 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.