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The C-terminal substrate-binding domain of LysR-type trnascriptional regulator BlaA which involved in control of the beta-lactamase gene expression; contains the type 2 periplasmic binding fold. This CD represents the C-terminal substrate binding domain of LysR-type transcriptional regulator, BlaA, that involved in control of the expression of beta-lactamase genes, blaA and blaB. Beta-lactamases are responsible for bacterial resistance to beta-lactam antibiotics such as penicillins. The blaA gene is located just upstream of blaB in the opposite direction and regulates the expression of the blaB. BlaA also negatively auto-regulates the expression of its own gene, blaA. BlaA (a constitutive class A penicllinase) belongs to the LysR family of transcriptional regulators, whereas BlaB (an inducible class C cephalosporinase or AmpC) can be referred to as a penicillin binding protein but it does not act as a beta-lactamase. 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. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",