Type 2 periplasmic binding fold superfamily; This evolutionary model and hierarchy represent the ligand-binding domains found in solute binding proteins that serve as initial receptors in the transport, signal transduction and channel gating. The PBP2 proteins share the same architecture as periplasmic binding proteins type 1 (PBP1), but have a different topology. They are typically comprised of two globular subdomains connected by a flexible hinge and bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap. The origin of PBP module can be traced across the distant phyla, including eukaryotes, archebacteria, and prokaryotes. The majority of PBP2 proteins are involved in the uptake of a variety of soluble substrates such as phosphate, sulfate, polysaccharides, lysine/arginine/ornithine, and histidine. 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 family includes ionotropic glutamate receptors and unorthodox sensor proteins involved in signal transduction. The substrate binding domain of the LysR transcriptional regulators and the oligopeptide-like transport systems also contain the type 2 periplasmic binding fold and thus they are significantly homologous to that of the PBP2; however, these two families are grouped into a separate hierarchy of the PBP2 superfamily due to the large number of protein sequences.

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                 ....*....|....*....|....*....|....*....|....*....|....
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDEL 68
Cdd:cd08422  144 GIALLPDFLVAEDLASGRLVRVLPDWRPPPLPIYAVYPSRRHLPAKVRAFIDFL 197

The C-terminal substrate binding domain of LysR-type transcriptional regulator CrgA and its related homologs, contains the type 2 periplasmic binding domain; This CD includes the substrate binding domain of LysR-type transcriptional regulator (LTTR) CrgA and its related homologs. The LTTRs are acting as both auto-repressors and activators of target promoters, controlling operons involved in a wide variety of cellular processes such as amino acid biosynthesis, CO2 fixation, antibiotic resistance, degradation of aromatic compounds, nodule formation of nitrogen-fixing bacteria, and synthesis of virulence factors, to name a few. In contrast to the tetrameric form of other LTTRs, CrgA from Neisseria meningitides assembles into an octameric ring, which can bind up to four 63-bp DNA oligonucleotides. Phylogenetic cluster analysis further showed that the CrgA-like regulators form a subclass of the LTTRs that function as octamers. The CrgA is an auto-repressor of its own gene and activates the expression of the mdaB gene which coding for an NADPH-quinone reductase and that its action is increased by MBL (alpha-methylene-gamma-butyrolactone), an inducer of NADPH-quinone oxidoreductase. The structural 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.

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                 ....*....|....*....|....*....|....*....|....*....|....
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDEL 68
Cdd:cd08422  144 GIALLPDFLVAEDLASGRLVRVLPDWRPPPLPIYAVYPSRRHLPAKVRAFIDFL 197

LysR substrate binding domain; The structure of this domain is known and is similar to the periplasmic binding proteins. This domain binds a variety of ligands that caries in size and structure, such as amino acids, sugar phosphates, organic acids, metal cations, flavonoids, C6-ring carboxylic acids, H2O2, HOCl, homocysteine, NADPH, ATP, sulphate, muropeptides, acetate, salicylate, citrate, phenol- and quinolone derivatives, acetylserines, fatty acid CoA, shikimate, chorismate, homocysteine, indole-3-acetic acid, Na(I), c-di-GMP, ppGpp and hydrogen peroxide (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 446467454    7 VRALVVLN-GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDELTTRLA 73
Cdd:pfam03466 138 LLQLVAAGlGIALLPRSAVARELADGRLVALPLPEPPLPRELYLVWRKGRPLSPAVRAFIEFLREALA 205

The C-terminal substrate binding domain of LysR-type transcriptional regulator CrgA and its related homologs, contains the type 2 periplasmic binding domain; This CD includes the substrate binding domain of LysR-type transcriptional regulator (LTTR) CrgA and its related homologs. The LTTRs are acting as both auto-repressors and activators of target promoters, controlling operons involved in a wide variety of cellular processes such as amino acid biosynthesis, CO2 fixation, antibiotic resistance, degradation of aromatic compounds, nodule formation of nitrogen-fixing bacteria, and synthesis of virulence factors, to name a few. In contrast to the tetrameric form of other LTTRs, CrgA from Neisseria meningitides assembles into an octameric ring, which can bind up to four 63-bp DNA oligonucleotides. Phylogenetic cluster analysis further showed that the CrgA-like regulators form a subclass of the LTTRs that function as octamers. The CrgA is an auto-repressor of its own gene and activates the expression of the mdaB gene which coding for an NADPH-quinone reductase and that its action is increased by MBL (alpha-methylene-gamma-butyrolactone), an inducer of NADPH-quinone oxidoreductase. The structural 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.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDEL 68
Cdd:cd08422  144 GIALLPDFLVAEDLASGRLVRVLPDWRPPPLPIYAVYPSRRHLPAKVRAFIDFL 197

DNA-binding transcriptional regulator, LysR family [Transcription];

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                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDELTTRLA 73
Cdd:COG0583  197 GIALLPRFLAADELAAGRLVALPLPDPPPPRPLYLVWRRRRHLSPAVRAFLDFLREALA 255

The C-terminal substrate binding domain of an uncharacterized LysR-type transcriptional regulator CrgA-like, contains the type 2 periplasmic binding fold; This CD represents the substrate binding domain of an uncharacterized LysR-type transcriptional regulator (LTTR) CrgA-like 3. The LTTRs are acting as both auto-repressors and activators of target promoters, controlling operons involved in a wide variety of cellular processes such as amino acid biosynthesis, CO2 fixation, antibiotic resistance, degradation of aromatic compounds, nodule formation of nitrogen-fixing bacteria, and synthesis of virulence factors, to name a few. In contrast to the tetrameric form of other LTTRs, CrgA from Neisseria meningitides assembles into an octameric ring, which can bind up to four 63-bp DNA oligonucleotides. Phylogenetic cluster analysis showed that the CrgA-like regulators form a subclass of the LTTRs that function as octamers. The CrgA is an auto-repressor of its own gene and activates the expression of the mdaB gene which coding for an NADPH-quinone reductase and that its action is increased by MBL (alpha-methylene-gamma-butyrolactone), an inducer of NADPH-quinone oxidoreductase. The structural 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.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMD 66
Cdd:cd08472  146 GIIQVPRFMVRPHLASGRLVEVLPDWRPPPLPVSLLYPHRRHLSPRVRVFVD 197

LysR family transcriptional regulator; Provisional

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                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDELTTRLA 73
Cdd:PRK14997 238 GLVQLPVLMVKEQLAAGELVAVLEEWEPRREVIHAVFPSRRGLLPSVRALVDFLTEEYA 296

The C-terminal substrate binding domain of an uncharacterized LysR-type transcriptional regulator CrgA-like, contains the type 2 periplasmic binding fold; This CD represents the substrate binding domain of an uncharacterized LysR-type transcriptional regulator (LTTR) CrgA-like 8. The LTTRs are acting as both auto-repressors and activators of target promoters, controlling operons involved in a wide variety of cellular processes such as amino acid biosynthesis, CO2 fixation, antibiotic resistance, degradation of aromatic compounds, nodule formation of nitrogen-fixing bacteria, and synthesis of virulence factors, to name a few. In contrast to the tetrameric form of other LTTRs, CrgA from Neisseria meningitides assembles into an octameric ring, which can bind up to four 63-bp DNA oligonucleotides. Phylogenetic cluster analysis showed that the CrgA-like regulators form a subclass of the LTTRs that function as octamers. The CrgA is an auto-repressor of its own gene and activates the expression of the mdaB gene which coding for an NADPH-quinone reductase and that its action is increased by MBL (alpha-methylene-gamma-butyrolactone), an inducer of NADPH-quinone oxidoreductase. The structural 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.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 446467454  15 GVALLPQFACKQGLANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMD 66
Cdd:cd08477  144 GIVLQPEALLAEDLASGRLVELLPDYLPPPRPMHLLYPPDRRPTPKLRSFID 195

The C-terminal substrate binding domain of an uncharacterized LysR-type transcriptional regulator CrgA-like, contains the type 2 periplasmic binding fold; This CD represents the substrate binding domain of an uncharacterized LysR-type transcriptional regulator (LTTR) CrgA-like 9. The LTTRs are acting as both auto-repressors and activators of target promoters, controlling operons involved in a wide variety of cellular processes such as amino acid biosynthesis, CO2 fixation, antibiotic resistance, degradation of aromatic compounds, nodule formation of nitrogen-fixing bacteria, and synthesis of virulence factors, to name a few. In contrast to the tetrameric form of other LTTRs, CrgA from Neisseria meningitides assembles into an octameric ring, which can bind up to four 63-bp DNA oligonucleotides. Phylogenetic cluster analysis showed that the CrgA-like regulators form a subclass of the LTTRs that function as octamers. The CrgA is an auto-repressor of its own gene and activates the expression of the mdaB gene which coding for an NADPH-quinone reductase and that its action is increased by MBL (alpha-methylene-gamma-butyrolactone), an inducer of NADPH-quinone oxidoreductase. The structural 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.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|.
gi 446467454  28 LANGELVRLFAPWSGIPRPLYALFAGRKGMPAIARYFMDEL 68
Cdd:cd08479  158 LRSGRLVRVLPDWQLPDADIWAVYPSRLSRSARVRVFVDFL 198