Protein Domain : HTH-type transcriptional activator IlvY, PBP2 domain IPR037404

Type	Domain
Description	In Escherichia coli, IlvY is required for the regulation of ilvC gene expression that encodes acetohydroxy acid isomeroreductase (AHIR), a key enzyme in the biosynthesis of branched-chain amino acids (isoleucine, valine, and leucine). The ilvGMEDA operon genes encode remaining enzyme activities required for the biosynthesis of these amino acids [ ]. Activation of ilvC transcription by IlvY requires the additional binding of a co-inducer molecule (either alpha-acetolactate or alpha-acetohydoxybutyrate, the substrates for AHIR) to a preformed complex of IlvY protein-DNA [ ]. Like many other LysR-family members, IlvY negatively auto-regulates the transcription of its own divergently transcribed ilvY gene in an inducer-independent manner []. This substrate-binding domain has significant homology to the type 2 periplasmic binding proteins (PBP2). The PBP2 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. Besides transport proteins, the PBP2 superfamily includes the substrate- binding domains from ionotropic glutamate receptors, LysR-like transcriptional regulators, and unorthodox sensor proteins involved in signal transduction [ , , ].
Short Name	IlvY_PBP2