[protein-PII] uridylyltransferase is a bifunctional uridylyltransferase/uridylyl-removing enzyme which modifies, by uridylylation and deuridylylation, the PII regulatory proteins GlnB and GlnK, in response to the nitrogen status of the cell
[Protein-PII] uridylyltransferase; This model describes GlnD, the uridylyltransferase ...
71-937
0e+00
[Protein-PII] uridylyltransferase; This model describes GlnD, the uridylyltransferase/uridylyl-removing enzyme for the nitrogen regulatory protein PII. Not all homologs of PII share the property of uridylyltransferase modification on the characteristic Tyr residue (see Prosite pattern PS00496 and document PDOC00439), but the modification site is preserved in the PII homolog of all species with a member of this family. [Central intermediary metabolism, Nitrogen metabolism, Regulatory functions, Protein interactions]
Pssm-ID: 273761 [Multi-domain] Cd Length: 850 Bit Score: 905.63 E-value: 0e+00
GlnD PII-uridylyltransferase; This is a family of bifunctional uridylyl-removing enzymes ...
229-367
3.89e-50
GlnD PII-uridylyltransferase; This is a family of bifunctional uridylyl-removing enzymes/uridylyltransferases (UR/UTases, GlnD) that are responsible for the modification (EC:2.7.7.59) of the regulatory protein P-II, or GlnB (pfam00543). In response to nitrogen limitation, these transferases catalyze the uridylylation of the PII protein, which in turn stimulates deadenylylation of glutamine synthetase (GlnA). Deadenylylated glutamine synthetase is the more active form of the enzyme. Moreover, uridylylated PII can act together with NtrB and NtrC to increase transcription of genes in the sigma54 regulon, which include glnA and other nitrogen-level controlled genes. It has also been suggested that the product of the glnD gene is involved in other physiological functions such as control of iron metabolism in certain species. The region described in this family is found in many of its members to be C-terminal to a nucleotidyltransferase domain (pfam01909), and N-terminal to an HD domain (pfam01966) and two ACT domains (pfam01842).
Pssm-ID: 462432 [Multi-domain] Cd Length: 140 Bit Score: 173.15 E-value: 3.89e-50
Nucleotidyltransferase (NT) domain of Escherichia coli adenylyltransferase (GlnE), Escherichia ...
67-217
4.54e-28
Nucleotidyltransferase (NT) domain of Escherichia coli adenylyltransferase (GlnE), Escherichia coli uridylyl transferase (GlnD), and similar proteins; Escherichia coli GlnD and -E participate in the Glutamine synthetase (GS)/Glutamate synthase (GOGAT) pathway for the assimilation of ammonium nitrogen. In nitrogen sufficiency, GlnE adenylates GS, reducing GS activity; when nitrogen is limiting, GlnE deadenylates GS-AMP, restoring GS activity. When nitrogen is limiting, GlnD uridylylates the nitrogen regulatory protein PII to PII-UTP, and in nitrogen sufficiency, it removes the modifying groups. The activity of Escherichia coli GlnE is modulated by PII-proteins. PII-UMP promotes GlnE deadenylation activity, and PII promotes GlnE adenylation activity. Escherichia coli GlnE has two separate NT domains. The N-terminal NT domain catalyzes the deadenylylation of GS, and the C-terminal NT domain the adenylylation reaction. The majority of proteins in this family contain a C-terminal NT domain which is associated with a cystathionine beta-synthase (CBS) domain pair and a CAP_ED (cAMP receptor protein effector ) domain. This family belongs to the Pol beta-like NT superfamily. In the majority of enzymes in this superfamily, two carboxylates, Dx[D/E], together with a third more distal carboxylate, coordinate two divalent metal cations involved in a two-metal ion mechanism of nucleotide addition. For the majority of proteins in this family, these carboxylate residues are conserved.
Pssm-ID: 143391 [Multi-domain] Cd Length: 172 Bit Score: 111.28 E-value: 4.54e-28
Metal dependent phosphohydrolases with conserved 'HD' motif; Includes eukaryotic cyclic ...
511-622
2.30e-04
Metal dependent phosphohydrolases with conserved 'HD' motif; Includes eukaryotic cyclic nucleotide phosphodiesterases (PDEc). This profile/HMM does not detect HD homologues in bacterial glycine aminoacyl-tRNA synthetases (beta subunit).
Pssm-ID: 214679 [Multi-domain] Cd Length: 124 Bit Score: 41.90 E-value: 2.30e-04
[Protein-PII] uridylyltransferase; This model describes GlnD, the uridylyltransferase ...
71-937
0e+00
[Protein-PII] uridylyltransferase; This model describes GlnD, the uridylyltransferase/uridylyl-removing enzyme for the nitrogen regulatory protein PII. Not all homologs of PII share the property of uridylyltransferase modification on the characteristic Tyr residue (see Prosite pattern PS00496 and document PDOC00439), but the modification site is preserved in the PII homolog of all species with a member of this family. [Central intermediary metabolism, Nitrogen metabolism, Regulatory functions, Protein interactions]
Pssm-ID: 273761 [Multi-domain] Cd Length: 850 Bit Score: 905.63 E-value: 0e+00
GlnD PII-uridylyltransferase; This is a family of bifunctional uridylyl-removing enzymes ...
229-367
3.89e-50
GlnD PII-uridylyltransferase; This is a family of bifunctional uridylyl-removing enzymes/uridylyltransferases (UR/UTases, GlnD) that are responsible for the modification (EC:2.7.7.59) of the regulatory protein P-II, or GlnB (pfam00543). In response to nitrogen limitation, these transferases catalyze the uridylylation of the PII protein, which in turn stimulates deadenylylation of glutamine synthetase (GlnA). Deadenylylated glutamine synthetase is the more active form of the enzyme. Moreover, uridylylated PII can act together with NtrB and NtrC to increase transcription of genes in the sigma54 regulon, which include glnA and other nitrogen-level controlled genes. It has also been suggested that the product of the glnD gene is involved in other physiological functions such as control of iron metabolism in certain species. The region described in this family is found in many of its members to be C-terminal to a nucleotidyltransferase domain (pfam01909), and N-terminal to an HD domain (pfam01966) and two ACT domains (pfam01842).
Pssm-ID: 462432 [Multi-domain] Cd Length: 140 Bit Score: 173.15 E-value: 3.89e-50
Nucleotidyltransferase (NT) domain of Escherichia coli adenylyltransferase (GlnE), Escherichia ...
67-217
4.54e-28
Nucleotidyltransferase (NT) domain of Escherichia coli adenylyltransferase (GlnE), Escherichia coli uridylyl transferase (GlnD), and similar proteins; Escherichia coli GlnD and -E participate in the Glutamine synthetase (GS)/Glutamate synthase (GOGAT) pathway for the assimilation of ammonium nitrogen. In nitrogen sufficiency, GlnE adenylates GS, reducing GS activity; when nitrogen is limiting, GlnE deadenylates GS-AMP, restoring GS activity. When nitrogen is limiting, GlnD uridylylates the nitrogen regulatory protein PII to PII-UTP, and in nitrogen sufficiency, it removes the modifying groups. The activity of Escherichia coli GlnE is modulated by PII-proteins. PII-UMP promotes GlnE deadenylation activity, and PII promotes GlnE adenylation activity. Escherichia coli GlnE has two separate NT domains. The N-terminal NT domain catalyzes the deadenylylation of GS, and the C-terminal NT domain the adenylylation reaction. The majority of proteins in this family contain a C-terminal NT domain which is associated with a cystathionine beta-synthase (CBS) domain pair and a CAP_ED (cAMP receptor protein effector ) domain. This family belongs to the Pol beta-like NT superfamily. In the majority of enzymes in this superfamily, two carboxylates, Dx[D/E], together with a third more distal carboxylate, coordinate two divalent metal cations involved in a two-metal ion mechanism of nucleotide addition. For the majority of proteins in this family, these carboxylate residues are conserved.
Pssm-ID: 143391 [Multi-domain] Cd Length: 172 Bit Score: 111.28 E-value: 4.54e-28
C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase ...
866-936
4.75e-22
C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD and related domains; This ACT domain family, ACT_ACR-UUR-like_2, includes the second of two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD are the second and fourth ACT domains of a novel protein composed almost entirely of ACT domain repeats, the ACR protein. These ACR proteins, found in Arabidopsis and Oryza, are proposed to function as novel regulatory or sensor proteins in plants. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153171 [Multi-domain] Cd Length: 70 Bit Score: 90.59 E-value: 4.75e-22
ACT domain family, ACT_UUR-like_1, includes the first of two C-terminal ACT domains of the ...
754-826
1.42e-20
ACT domain family, ACT_UUR-like_1, includes the first of two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD and related domains; This ACT domain family, ACT_UUR-like_1, includes the first of two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD is the N-terminal ACT domain of a yet characterized Arabidopsis/Oryza predicted tyrosine kinase. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153172 [Multi-domain] Cd Length: 73 Bit Score: 86.38 E-value: 1.42e-20
ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) ...
866-936
4.02e-19
ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; This ACT domain family, ACT_UUR_ACR-like, includes the two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD are the four ACT domains of a novel protein composed almost entirely of ACT domain repeats (the ACR protein) and like proteins. These ACR proteins, found in Arabidopsis and Oryza, are proposed to function as novel regulatory or sensor proteins in plants. This CD also includes the first of the two ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein and related domains, as well as, the N-terminal ACT domain of a yet characterized Arabidopsis/Oryza predicted tyrosine kinase. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153145 [Multi-domain] Cd Length: 70 Bit Score: 82.21 E-value: 4.02e-19
ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) ...
755-826
5.93e-10
ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; This ACT domain family, ACT_UUR_ACR-like, includes the two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD are the four ACT domains of a novel protein composed almost entirely of ACT domain repeats (the ACR protein) and like proteins. These ACR proteins, found in Arabidopsis and Oryza, are proposed to function as novel regulatory or sensor proteins in plants. This CD also includes the first of the two ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein and related domains, as well as, the N-terminal ACT domain of a yet characterized Arabidopsis/Oryza predicted tyrosine kinase. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153145 [Multi-domain] Cd Length: 70 Bit Score: 56.02 E-value: 5.93e-10
ACT domain-containing protein which is composed almost entirely of four ACT domain repeats ...
866-936
2.67e-09
ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein); This CD includes the second ACT domain, of a novel type of ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein). ACR proteins, found only in Arabidopsis and Oryza, as yet, are proposed to function as novel regulatory or sensor proteins in plants. Nine ACR gene products have been described (ACR1-8 in Arabidopsis and OsARC1-9 in Oryza) and are represented in this CD. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153197 Cd Length: 74 Bit Score: 54.36 E-value: 2.67e-09
C-terminal ACT domain, of a novel type of ACT domain-containing protein which is composed ...
868-930
7.38e-07
C-terminal ACT domain, of a novel type of ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein); This CD includes the C-terminal ACT domain, of a novel type of ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein). ACR proteins, found only in Arabidopsis and Oryza, as yet, are proposed to function as novel regulatory or sensor proteins in plants. Nine ACR gene products have been described (ACR1-8 in Arabidopsis and OsARC1-9 in Oryza) and are represented in this CD. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153198 Cd Length: 72 Bit Score: 47.34 E-value: 7.38e-07
ACT domain family, ACT_UUR-like_1, includes the first of two C-terminal ACT domains of the ...
874-936
8.05e-07
ACT domain family, ACT_UUR-like_1, includes the first of two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD and related domains; This ACT domain family, ACT_UUR-like_1, includes the first of two C-terminal ACT domains of the bacterial signal-transducing uridylyltransferase /uridylyl-removing (UUR) enzyme, GlnD; including those enzymes similar to the GlnD found in enteric Escherichia coli and those found in photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum. Also included in this CD is the N-terminal ACT domain of a yet characterized Arabidopsis/Oryza predicted tyrosine kinase. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153172 [Multi-domain] Cd Length: 73 Bit Score: 47.47 E-value: 8.05e-07
ACT domain; This family of domains generally have a regulatory role. ACT domains are linked to ...
866-911
1.05e-06
ACT domain; This family of domains generally have a regulatory role. ACT domains are linked to a wide range of metabolic enzymes that are regulated by amino acid concentration. Pairs of ACT domains bind specifically to a particular amino acid leading to regulation of the linked enzyme. The ACT domain is found in: D-3-phosphoglycerate dehydrogenase EC:1.1.1.95, which is inhibited by serine. Aspartokinase EC:2.7.2.4, which is regulated by lysine. Acetolactate synthase small regulatory subunit, which is inhibited by valine. Phenylalanine-4-hydroxylase EC:1.14.16.1, which is regulated by phenylalanine. Prephenate dehydrogenase EC:4.2.1.51. formyltetrahydrofolate deformylase EC:3.5.1.10, which is activated by methionine and inhibited by glycine. GTP pyrophosphokinase EC:2.7.6.5
Pssm-ID: 426468 [Multi-domain] Cd Length: 66 Bit Score: 46.92 E-value: 1.05e-06
ACT domain-containing protein which is composed almost entirely of four ACT domain repeats ...
866-932
1.18e-06
ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein); This CD includes the N-terminal ACT domain, of a novel type of ACT domain-containing protein which is composed almost entirely of four ACT domain repeats (the "ACR" protein). ACR proteins, found only in Arabidopsis and Oryza, as yet, are proposed to function as novel regulatory or sensor proteins in plants. Nine ACR gene products have been described (ACR1-8 in Arabidopsis and OsARC1-9 in Oryza) and are represented in this CD. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153167 [Multi-domain] Cd Length: 72 Bit Score: 46.68 E-value: 1.18e-06
ACT domains are commonly involved in specifically binding an amino acid or other small ligand ...
868-932
6.45e-06
ACT domains are commonly involved in specifically binding an amino acid or other small ligand leading to regulation of the enzyme; Members of this CD belong to the superfamily of ACT regulatory domains. Pairs of ACT domains are commonly involved in specifically binding an amino acid or other small ligand leading to regulation of the enzyme. The ACT domain has been detected in a number of diverse proteins; some of these proteins are involved in amino acid and purine biosynthesis, phenylalanine hydroxylation, regulation of bacterial metabolism and transcription, and many remain to be characterized. ACT domain-containing enzymes involved in amino acid and purine synthesis are in many cases allosteric enzymes with complex regulation enforced by the binding of ligands. The ACT domain is commonly involved in the binding of a small regulatory molecule, such as the amino acids L-Ser and L-Phe in the case of D-3-phosphoglycerate dehydrogenase and the bifunctional chorismate mutase-prephenate dehydratase enzyme (P-protein), respectively. Aspartokinases typically consist of two C-terminal ACT domains in a tandem repeat, but the second ACT domain is inserted within the first, resulting in, what is normally the terminal beta strand of ACT2, formed from a region N-terminal of ACT1. ACT domain repeats have been shown to have nonequivalent ligand-binding sites with complex regulatory patterns such as those seen in the bifunctional enzyme, aspartokinase-homoserine dehydrogenase (ThrA). In other enzymes, such as phenylalanine hydroxylases, the ACT domain appears to function as a flexible small module providing allosteric regulation via transmission of conformational changes, these conformational changes are not necessarily initiated by regulatory ligand binding at the ACT domain itself. ACT domains are present either singularly, N- or C-terminal, or in pairs present C-terminal or between two catalytic domains. Unique to cyanobacteria are four ACT domains C-terminal to an aspartokinase domain. A few proteins are composed almost entirely of ACT domain repeats as seen in the four ACT domain protein, the ACR protein, found in higher plants; and the two ACT domain protein, the glycine cleavage system transcriptional repressor (GcvR) protein, found in some bacteria. Also seen are single ACT domain proteins similar to the Streptococcus pneumoniae ACT domain protein (uncharacterized pdb structure 1ZPV) found in both bacteria and archaea. Purportedly, the ACT domain is an evolutionarily mobile ligand binding regulatory module that has been fused to different enzymes at various times.
Pssm-ID: 153139 [Multi-domain] Cd Length: 60 Bit Score: 44.21 E-value: 6.45e-06
Metal dependent phosphohydrolases with conserved 'HD' motif; Includes eukaryotic cyclic ...
511-622
2.30e-04
Metal dependent phosphohydrolases with conserved 'HD' motif; Includes eukaryotic cyclic nucleotide phosphodiesterases (PDEc). This profile/HMM does not detect HD homologues in bacterial glycine aminoacyl-tRNA synthetases (beta subunit).
Pssm-ID: 214679 [Multi-domain] Cd Length: 124 Bit Score: 41.90 E-value: 2.30e-04
ACT domain found C-terminal of the RelA/SpoT domains; ACT_RelA-SpoT: the ACT domain found ...
868-904
5.14e-04
ACT domain found C-terminal of the RelA/SpoT domains; ACT_RelA-SpoT: the ACT domain found C-terminal of the RelA/SpoT domains. Enzymes of the Rel/Spo family enable bacteria to survive prolonged periods of nutrient limitation by controlling guanosine-3'-diphosphate-5'-(tri)diphosphate ((p)ppGpp) production and subsequent rRNA repression (stringent response). Both the synthesis of (p)ppGpp from ATP and GDP(GTP), and its hydrolysis to GDP(GTP) and pyrophosphate, are catalyzed by Rel/Spo proteins. In Escherichia coli and its close relatives, the metabolism of (p)ppGpp is governed by two homologous proteins, RelA and SpoT. The RelA protein catalyzes (p)ppGpp synthesis in a reaction requiring its binding to ribosomes bearing codon-specified uncharged tRNA. The major role of the SpoT protein is the breakdown of (p)ppGpp by a manganese-dependent (p)ppGpp pyrophosphohydrolase activity. Although the stringent response appears to be tightly regulated by these two enzymes in E. coli, a bifunctional Rel/Spo protein has been discovered in most gram-positive organisms studied so far. These bifunctional Rel/Spo homologs (rsh) appear to modulate (p)ppGpp levels through two distinct active sites that are controlled by a reciprocal regulatory mechanism ensuring inverse coupling of opposing activities. In studies with the Streptococcus equisimilis Rel/Spo homolog, the C-terminal domain appears to be involved in this reciprocal regulation of the two opposing catalytic activities present in the N-terminal domain, ensuring that both synthesis and degradation activities are not coinduced. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153148 [Multi-domain] Cd Length: 71 Bit Score: 39.36 E-value: 5.14e-04
Nucleotidyltransferase domain; Members of this family belong to a large family of ...
124-148
2.02e-03
Nucleotidyltransferase domain; Members of this family belong to a large family of nucleotidyltransferases. This family includes kanamycin nucleotidyltransferase (KNTase) which is a plasmid-coded enzyme responsible for some types of bacterial resistance to aminoglycosides. KNTase in-activates antibiotics by catalysing the addition of a nucleotidyl group onto the drug.
Pssm-ID: 396474 Cd Length: 91 Bit Score: 38.17 E-value: 2.02e-03
Uncharacterized, N-terminal ACT domain of an Arabidopsis/Oryza predicted tyrosine kinase and ...
868-912
2.31e-03
Uncharacterized, N-terminal ACT domain of an Arabidopsis/Oryza predicted tyrosine kinase and other related ACT domains; This CD includes a novel, yet uncharacterized, N-terminal ACT domain of an Arabidopsis/Oryza predicted tyrosine kinase and other related ACT domains. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153200 Cd Length: 68 Bit Score: 37.54 E-value: 2.31e-03
ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein, ...
867-895
8.27e-03
ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein, and other related domains; This CD includes the second of the two ACT domains that comprise the Glycine Cleavage System Transcriptional Repressor (GcvR) protein, and other related domains. The glycine cleavage enzyme system in Escherichia coli provides one-carbon units for cellular methylation reactions. This enzyme system, encoded by the gcvTHP operon and lpd gene, catalyzes the cleavage of glycine into CO2 + NH3 and transfers a one-carbon unit to tetrahydrofolate, producing 5,10-methylenetetrahydrofolate. The gcvTHP operon is activated by the GcvA protein in response to glycine and repressed by a GcvA/GcvR interaction in the absence of glycine. It has been proposed that the co-activator glycine acts through a mechanism of de-repression by binding to GcvR and preventing GcvR from interacting with GcvA to block GcvA's activator function. Evidence also suggests that GcvR interacts directly with GcvA rather than binding to DNA to cause repression. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153141 [Multi-domain] Cd Length: 81 Bit Score: 36.05 E-value: 8.27e-03
N-terminal ACT domain of the yet uncharacterized, small (~133 a.a.), putative amino acid ...
757-825
9.06e-03
N-terminal ACT domain of the yet uncharacterized, small (~133 a.a.), putative amino acid binding protein, Af1403, and related domains; This CD includes the N-terminal ACT domain of the yet uncharacterized, small (~133 a.a.), putative amino acid binding protein, Af1403, from Archaeoglobus fulgidus and other related archeal ACT domains. Members of this CD belong to the superfamily of ACT regulatory domains.
Pssm-ID: 153146 [Multi-domain] Cd Length: 72 Bit Score: 35.74 E-value: 9.06e-03
ACT domains are commonly involved in specifically binding an amino acid or other small ligand ...
757-804
9.25e-03
ACT domains are commonly involved in specifically binding an amino acid or other small ligand leading to regulation of the enzyme; Members of this CD belong to the superfamily of ACT regulatory domains. Pairs of ACT domains are commonly involved in specifically binding an amino acid or other small ligand leading to regulation of the enzyme. The ACT domain has been detected in a number of diverse proteins; some of these proteins are involved in amino acid and purine biosynthesis, phenylalanine hydroxylation, regulation of bacterial metabolism and transcription, and many remain to be characterized. ACT domain-containing enzymes involved in amino acid and purine synthesis are in many cases allosteric enzymes with complex regulation enforced by the binding of ligands. The ACT domain is commonly involved in the binding of a small regulatory molecule, such as the amino acids L-Ser and L-Phe in the case of D-3-phosphoglycerate dehydrogenase and the bifunctional chorismate mutase-prephenate dehydratase enzyme (P-protein), respectively. Aspartokinases typically consist of two C-terminal ACT domains in a tandem repeat, but the second ACT domain is inserted within the first, resulting in, what is normally the terminal beta strand of ACT2, formed from a region N-terminal of ACT1. ACT domain repeats have been shown to have nonequivalent ligand-binding sites with complex regulatory patterns such as those seen in the bifunctional enzyme, aspartokinase-homoserine dehydrogenase (ThrA). In other enzymes, such as phenylalanine hydroxylases, the ACT domain appears to function as a flexible small module providing allosteric regulation via transmission of conformational changes, these conformational changes are not necessarily initiated by regulatory ligand binding at the ACT domain itself. ACT domains are present either singularly, N- or C-terminal, or in pairs present C-terminal or between two catalytic domains. Unique to cyanobacteria are four ACT domains C-terminal to an aspartokinase domain. A few proteins are composed almost entirely of ACT domain repeats as seen in the four ACT domain protein, the ACR protein, found in higher plants; and the two ACT domain protein, the glycine cleavage system transcriptional repressor (GcvR) protein, found in some bacteria. Also seen are single ACT domain proteins similar to the Streptococcus pneumoniae ACT domain protein (uncharacterized pdb structure 1ZPV) found in both bacteria and archaea. Purportedly, the ACT domain is an evolutionarily mobile ligand binding regulatory module that has been fused to different enzymes at various times.
Pssm-ID: 153139 [Multi-domain] Cd Length: 60 Bit Score: 35.35 E-value: 9.25e-03
Database: CDSEARCH/cdd Low complexity filter: no Composition Based Adjustment: yes E-value threshold: 0.01
References:
Wang J et al. (2023), "The conserved domain database in 2023", Nucleic Acids Res.51(D)384-8.
Lu S et al. (2020), "The conserved domain database in 2020", Nucleic Acids Res.48(D)265-8.
Marchler-Bauer A et al. (2017), "CDD/SPARCLE: functional classification of proteins via subfamily domain architectures.", Nucleic Acids Res.45(D)200-3.
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