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.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 2339708270   1 YFMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWLGADYS 41
Cdd:cd13710   193 YFLFNKDQQKLQKDIDKALKELKKDGTLKKLSKKYFGGDYF 233

Substrate binding domain of an ABC transporter TcyJKLMN; the type 2 periplasmic binding protein fold; This group contains periplasmic cystine-binding domain (TcyK) of an ATP-binding cassette transporter from Bacillus subtilus and its closely related proteins. Cystine is an oxidized dimeric form of cysteine that is required for optimal bacterial growth. In Bacillus subtilis, three ABC transporters, TcyJKLMN (YtmJKLMN), TcyABC (YckKJI), and YxeMNO are involved in uptake of cystine. Likewise, three uptake systems were identified in Salmonella enterica serovar Typhimurium, while in Escherichia coli, two transport systems seem to be involved in cystine uptake. Moreover, L-cystine limitation was shown to prevent virulence of Neisseria gonorrhoeae; thus, its L-cystine solute receptor (Ngo0372) may be suited as target for an antimicrobial vaccine. The cystine receptor belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 2339708270   1 YFMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWLGADYS 41
Cdd:cd13710   193 YFLFNKDQQKLQKDIDKALKELKKDGTLKKLSKKYFGGDYF 233

cystine ABC transporter substrate-binding protein;

                          10        20        30
                  ....*....|....*....|....*....|....*..
gi 2339708270   6 KNSQTLADDTDRAIQKLEKDGTLKRLSEKWLGADYSK 42
Cdd:PRK11260  230 KGNPDLLKAVNQAIAEMQKDGTLKALSEKWFGADVTK 266

Bacterial periplasmic substrate-binding proteins; bacterial proteins, eukaryotic ones are in PBPe

                           10        20        30
                   ....*....|....*....|....*....|....*.
gi 2339708270    1 YFMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWL 36
Cdd:smart00062 184 AIAVRKGDPELLDKINKALKELKADGTLKKISEKWF 219

Substrate binding domain of an ABC transporter TcyJKLMN; the type 2 periplasmic binding protein fold; This group contains periplasmic cystine-binding domain (TcyK) of an ATP-binding cassette transporter from Bacillus subtilus and its closely related proteins. Cystine is an oxidized dimeric form of cysteine that is required for optimal bacterial growth. In Bacillus subtilis, three ABC transporters, TcyJKLMN (YtmJKLMN), TcyABC (YckKJI), and YxeMNO are involved in uptake of cystine. Likewise, three uptake systems were identified in Salmonella enterica serovar Typhimurium, while in Escherichia coli, two transport systems seem to be involved in cystine uptake. Moreover, L-cystine limitation was shown to prevent virulence of Neisseria gonorrhoeae; thus, its L-cystine solute receptor (Ngo0372) may be suited as target for an antimicrobial vaccine. The cystine receptor belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 2339708270   1 YFMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWLGADYS 41
Cdd:cd13710   193 YFLFNKDQQKLQKDIDKALKELKKDGTLKKLSKKYFGGDYF 233

Substrate binding domain of ABC transporters involved in cystine import; the type 2 periplasmic binding protein fold; This subgroup includes cystine-binding domain of periplasmic receptor-dependent ATP-binding cassette transporters from Neisseria gonorrhoeae and Bacillus subtilis and their related proteins. Cystine is an oxidized dimeric form of cysteine that is required for optimal bacterial growth. In Bacillus subtilis, three ABC transporters, TcyJKLMN (YtmJKLMN), TcyABC (YckKJI), and YxeMNO are involved in uptake of cystine. Likewise, three uptake systems were identified in Salmonella enterica serovar Typhimurium, while in Escherichia coli, two transport systems seem to be involved in cystine uptake. Moreover, L-cystine limitation was shown to prevent virulence of Neisseria gonorrhoeae; thus, its L-cystine solute receptor (Ngo0372) may be suited as target for an antimicrobial vaccine. The cystine receptor belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30
                  ....*....|....*....|....*....|....*....
gi 2339708270   1 YFMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWLGAD 39
Cdd:cd13711   183 AFLVRKGNDELVAAINKALKELKADGTLKKISEKYFGKD 221

Substrate binding domain of an ABC transporter YxeMNO; the type 2 periplasmic binding protein fold; This group contains cystine-binding domain (YxeM) of a periplasmic receptor-dependent ATP-binding cassette transporter and its closely related proteins. Cystine is an oxidized dimeric form of cysteine that is required for optimal bacterial growth. In Bacillus subtilis, three ABC transporters, TcyJKLMN (YtmJKLMN), TcyABC (YckKJI), and YxeMNO are involved in uptake of cystine. Likewise, three uptake systems were identified in Salmonella enterica serovar Typhimurium, while in Escherichia coli, two transport systems seem to be involved in cystine uptake. Moreover, L-cystine limitation was shown to prevent virulence of Neisseria gonorrhoeae; thus, its L-cystine solute receptor (Ngo0372) may be suited as target for an antimicrobial vaccine. The cystine receptor belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|
gi 2339708270   2 FMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWLGADYS 41
Cdd:cd13709   188 FVKNEKGKKLLEKVNKALEEMRKDGTLKKISEKWFGIDIT 227

Bacterial extracellular solute-binding proteins, family 3; This is a sensor domain found in solute-binding protein family 3 members from Gram-positive bacteria, Gram-negative bacteria and archaea. It can also be found in the N-terminal of the membrane-bound lytic murein transglycosylase F (MltF) protein. This domain recognizes Nicotinate, quidalnate, pyridine-2,5-dicarboxylate and salicylate (Matilla et. al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 2339708270   1 YFMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWL 36
Cdd:pfam00497 186 GIAVRKGDPELLAAVNKALAELKADGTLAKIYEKWF 221

Peptide-binding protein and related homologs; type 2 periplasmic binding protein fold; This domain is found in solute binding proteins that serve as initial receptors in the ABC transport, signal transduction and channel gating. The PBP2 proteins share the same architecture as periplasmic binding proteins type 1, 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 majority of PBP2 proteins function in the uptake of small soluble substrates in eubacteria and archaea. 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.

                          10        20        30
                  ....*....|....*....|....*....|....
gi 2339708270   2 FMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKW 35
Cdd:cd13530   184 IAVRKGNPELLDAINKALAELKADGTLDKLLEKW 217

Substrate binding domain of an Escherichia coli ABC transporter; the type 2 periplasmic binding protein fold; This group contains cystine binding domain FliY and its related proteins. Cystine is an oxidized dimeric form of cysteine that is required for optimal bacterial growth. In Bacillus subtilis, three ABC transporters, TcyJKLMN (YtmJKLMN), TcyABC (YckKJI), and YxeMNO are involved in uptake of cystine. Likewise, three uptake systems were identified in Salmonella enterica serovar Typhimurium, while in Escherichia coli, two transport systems seem to be involved in cystine uptake. Moreover, L-cystine limitation was shown to prevent virulence of Neisseria gonorrhoeae; thus, its L-cystine solute receptor (Ngo0372) may be suited as target for an antimicrobial vaccine. The cystine receptor belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30
                  ....*....|....*....|....*....|....
gi 2339708270   4 FNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWLG 37
Cdd:cd13712   186 FRKGNPKLKAAINKAIEDLRADGTLAKLSEKWFG 219

Substrate binding domain of ABC-type octopine transporter-like; the type 2 periplasmic-binding protein fold; This group includes periplasmic octopine-binding protein and related proteins. This group belongs to the type 2 periplasmic-binding fold protein (PBP2) superfamily, whose members are involved in chemotaxis and uptake of nutrients and other small molecules from the extracellular space as a primary receptor. PBP2 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30
                  ....*....|....*....|....*....|..
gi 2339708270   4 FNKNSQTLADDTDRAIQKLEKDGTLKRLSEKW 35
Cdd:cd13699   179 LRKGDTELKAKFDSAIKAAVADGTVKKLSEKW 210

Plant glutamate receptor domain; the type 2 periplasmic binding protein fold; This subfamily contains the glutamate receptor domain GluR. These domains are found in the GluR proteins that have been shown to function as L-glutamate activated potassium channels, also known ionotropic glutamate receptors or iGluRs. In addition to two ligand binding core domains, iGluRs typically have a channel-like domain inserted in the middle of the GluR-like domain. Animal iGluRs mediate the ion flux in the synapses of the CNS and can be subdivided into several classes depending on the neurotransmitter specificity and ion conductance properties. Their plant homologs have been shown to function in light signal transduction and calcium homeostasis. The GluR proteins belong to the PBP2 superfamily of periplasmic binding proteins that differ in size and ligand specificity, but have similar tertiary structures consisting of two globular subdomains connected by a flexible hinge. They have been shown to bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 2339708270   2 FMFNKNSQtLADDTDRAIQKLEKDGTLKRLSEKWL 36
Cdd:cd13686   199 FAFPKGSP-LVADVSRAILKVTEGGKLQQIENKWF 232

Substrate binding domain of an ABC cystine transporter; the type 2 periplasmic binding protein fold; Periplasmic cystine-binding domain (YckB) of an ATP-binding cassette (ABC) transporter from Bacillus subtilis and its related proteins. Cystine is an oxidized dimeric form of cysteine that is required for optimal bacterial growth. In Bacillus subtilis, three ABC transporters, TcyJKLMN (YtmJKLMN), TcyABC (YckKJI), and YxeMNO are involved in uptake of cystine. Likewise, three uptake systems were identified in Salmonella enterica serovar Typhimurium, while in Escherichia coli, two transport systems seem to be involved in cystine uptake. Moreover, L-cystine limitation was shown to prevent virulence of Neisseria gonorrhoeae; thus, its L-cystine solute receptor (Ngo0372) may be suited as target for an antimicrobial vaccine. The cystine receptor belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins are typically comprises 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|.
gi 2339708270   2 FMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWL-GADYS 41
Cdd:cd01003   189 LVMKKSNAALQEKVNKALKEMSKDGTLTKISEQFFnGADVS 229

Bacterial GluR0 ligand-binding domain; the type 2 periplasmic binding protein fold; Glutamate receptor domain GluR0. These domains are found in the GluR0 proteins that have been shown to function as prokaryotic L-glutamate activated potassium channels, also known ionotropic glutamate receptors or iGluRs. In addition to two ligand binding core domains, iGluRs typically have a channel-like domain inserted in the middle of the GluR-like domain. The GluR0 proteins belong to the PBP2 superfamily of periplasmic binding proteins that differ in size and ligand specificity, but have similar tertiary structures consisting of two globular subdomains connected by a flexible hinge. They have been shown to bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap.

                          10        20        30
                  ....*....|....*....|....*....|....*.
gi 2339708270   2 FMFNKNSqTLADDTDRAIQKLEKDGTLKRLSEKWLG 37
Cdd:cd00997   184 IVFPTGS-PLRKPINQALLNLREDGTYDELYEKWFG 218

lysine-arginine-ornithine-binding periplasmic protein; [Transport and binding proteins, Amino acids, peptides and amines]

                          10        20        30
                  ....*....|....*....|....*....|.
gi 2339708270   6 KNSQTLADDTDRAIQKLEKDGTLKRLSEKWL 36
Cdd:TIGR01096 220 KGDTELKAAFNKALAAIRADGTYQKISKKWF 250

Substrate binding domain of the arginine-, lysine-, histidine-binding protein ArtJ; the type 2 periplasmic binding protein fold; This group includes the periplasmic substrate-binding protein ArtJ of the ATP-binding cassette (ABC) transport system from the thermophilic bacterium Geobacillus stearothermophilus, which is specific for arginine, lysine, and histidine. ArtJ belongs to the type 2 periplasmic-binding fold protein (PBP2) superfamily, whose members are involved in chemotaxis and uptake of nutrients and other small molecules from the extracellular space as a primary receptor. PBP2 typically comprises 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30
                  ....*....|....*....|....*....|....*
gi 2339708270   2 FMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKWL 36
Cdd:cd13624   185 IAVRKGNKELLDKINKALKKIKENGTYDKIYKKWF 219

Substrate binding domain of an ABC aspartate/glutamate transporter; the type 2 periplasmic-binding protein fold; This group includes periplasmic aspartate/glutamate binding domain Peb1a and its closely related protein. The Peb1a is an important virulence factor in the food-borne human pathogen Campylobacter jejuni, which has a major role in adherence and host colonization. The Peb1a domain belongs to the type 2 periplasmic binding protein fold superfamily (PBP2), whose many members are involved in chemotaxis and uptake of nutrients and other small molecules from the extracellular space as a primary receptor. The PBP2 proteins 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30
                  ....*....|....*....|....*....|
gi 2339708270   6 KNSQTLADDTDRAIQKLEKDGTLKRLSEKW 35
Cdd:cd13691   198 KGSTDLSKYVDDAVKKWLADGTLEALIKKW 227

Mimosine binding domain of ABC-type transporter MidA and similar proteins; the type 2 periplasmic binding protein fold; This subgroup includes the periplasmic binding component of ABC transporter involved in uptake of mimosine MidA and its similar proteins. This periplasmic binding domain belongs to the type 2 periplasmic-binding fold protein (PBP2) superfamily, whose members are involved in chemotaxis and uptake of nutrients and other small molecules from the extracellular space as a primary receptor. PBP2 typically comprises 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. 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 receptor cytoplasmically-located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.

                          10        20        30
                  ....*....|....*....|....*....|....
gi 2339708270   2 FMFNKNSQTLADDTDRAIQKLEKDGTLKRLSEKW 35
Cdd:cd01004   195 IAVKKDDPALADAVQAALNALIADGTYKKILKKW 228