3.5.2.3: dihydroorotase
This is an abbreviated version!
For detailed information about dihydroorotase, go to the full flat file.
Word Map on EC 3.5.2.3
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3.5.2.3
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pyrimidine
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transcarbamoylase
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carbamoyl-phosphate
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phosphoribosyltransferase
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atcase
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orotidine
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carbamoyltransferase
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glutamine-dependent
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l-dihydroorotate
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2.1.3.2
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cpsase
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pyre
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dihydropyrimidinase
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hydantoinase
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dihydro-ouabain
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n-phosphonacetyl-l-aspartate
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n-carbamyl-l-aspartate
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allantoinase
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imidase
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synthesis
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succinate-grown
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amidohydrolases
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6.3.5.5
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drug development
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medicine
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5-fluoroorotate
- 3.5.2.3
- pyrimidine
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transcarbamoylase
- carbamoyl-phosphate
- phosphoribosyltransferase
- atcase
- orotidine
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carbamoyltransferase
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glutamine-dependent
- l-dihydroorotate
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2.1.3.2
- cpsase
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pyre
- dihydropyrimidinase
- hydantoinase
- dihydro-ouabain
- n-phosphonacetyl-l-aspartate
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n-carbamyl-l-aspartate
- allantoinase
- imidase
- synthesis
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succinate-grown
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amidohydrolases
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6.3.5.5
- drug development
- medicine
- 5-fluoroorotate
Reaction
Synonyms
amidohydrolase family protein, BcDHOase, CAD, carbamoylaspartic dehydrase, Class I DHOase, DHO, DHOase, dihydroorotase, dihydroorotase domain, dihydroorotate dehydrolase, hDHOase, huDHOase, human DHOase domain, LdDHOase, More, pyrC, type I DHOase, type II DHO, VcDHO, YpDHO
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General Information
General Information on EC 3.5.2.3 - dihydroorotase
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evolution
malfunction
metabolism
physiological function
additional information
despite evolutionary divergence, the CAD DHOase active site components are highly conserved with those in bacterial DHOases, encoded as monofunctional enzymes. An important element for catalysis, conserved from Escherichia coli to humans, is a flexible loop that closes as a lid over the active site. The flexible loop exhibits a two-amino acid signature that is characteristic for each DHOase type
evolution
dihydroorotase (DHO) is an amidohydrolase that catalyzes the reversible condensation of carbamoyl aspartate to form dihydroorotate in de novo pyrimidine biosynthesis in virtually all organisms. Although the same reaction is catalyzed by all DHOs, the structure, oligomeric organization, and metal content of this family of enzymes is diverse
evolution
dihydroorotase (DHOase) is a member of the cyclic amidohydrolase family, which also includes allantoinase, hydantoinase, dihydropyrimidinase (DHPase), and imidase. Almost all of these zinc metalloenzymes possess a binuclear metal center in which two metal ions are bridged by a post-translational carbamylated Lys
evolution
mammals have a large, multifunctional dihydroorotate synthetase (CAD) enzyme for the first three steps of the de novo pyrimidine biosynthesis pathway, while prokaryotes use three separate monofunctional enzymes for each. DHOase is divided into two evolutionary classes, with very low sequence identity (< 30%) between classes. Class I DHOases are found in gram-positive bacteria, mold, and insects, while Class II DHOases are found in gram-negative bacteria and fungi. The major structural difference between the Class I and Class II DHOase is the longer catalytic loop of Class II counterparts
evolution
the enzyme belongs to the amidohydrolase superfamily
evolution
the structure of YpDHO has essentially the same conformation as the structure of DHO from Escherichia coli (EcDHO), the most thoroughly studied bacterial type II DHO. The enzyme belongs to the amidohydrolase superfamily
evolution
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mammals have a large, multifunctional dihydroorotate synthetase (CAD) enzyme for the first three steps of the de novo pyrimidine biosynthesis pathway, while prokaryotes use three separate monofunctional enzymes for each. DHOase is divided into two evolutionary classes, with very low sequence identity (< 30%) between classes. Class I DHOases are found in gram-positive bacteria, mold, and insects, while Class II DHOases are found in gram-negative bacteria and fungi. The major structural difference between the Class I and Class II DHOase is the longer catalytic loop of Class II counterparts
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evolution
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the enzyme belongs to the amidohydrolase superfamily
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evolution
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the enzyme belongs to the amidohydrolase superfamily
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a huDHOase chimera bearing the Escherichia coli DHOase flexible loop is inactive, suggesting the presence of distinctive elements in the flexible loop of huDHOase that cannot be replaced by the bacterial sequence. Substitutions of Phe1563 with Ala, Leu, or Thr prevent the closure of the flexible loop and inactivated the protein, whereas substitution with Tyr enhances the interactions of the loop in the closed position and reduced fluctuations and the reaction rate
malfunction
a parallel salvage pathway of pyrimidine biosynthesis exists, since kaempferol cannot completely inhibit the pathway in vivo
malfunction
the replacement of the zinc ligand Cys181 with glycine does not restore the latent catalytic activity suggesting that it plays a minor role in stabilizing loop A
malfunction
Leishmania donovani BHU 1081
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a parallel salvage pathway of pyrimidine biosynthesis exists, since kaempferol cannot completely inhibit the pathway in vivo
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third enzyme in the bacterial de novo pyrimidine biosynthesis pathway, overview
metabolism
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catalyzes the conversion of N-carbamoyl-L-aspartate to dihydroorotate in the third step of the de novo biosynthesis of pyrimidines
metabolism
de novo pyrimidine biosynthesis pathway is well developed and functional in protozoan parasite Leishmania donovani. The dihydroorotase (LdDHOase) is the third enzyme of the pathway
metabolism
dihydroorotase (DHO) is an amidohydrolase that catalyzes the reversible condensation of carbamoyl aspartate to form dihydroorotate in de novo pyrimidine biosynthesis
metabolism
dihydroorotase (DHOase) catalyses the third reaction of the de novo pyrimidine biosynthetic pathway, the reversible condensation of carbamylaspartate into dihydroorotate
metabolism
the de novo pyrimidine biosynthesis pathway is essential for the proliferation of many pathogens. One of the pathway enzymes, dihydroorotase (DHO), catalyzes the reversible interconversion of N-carbamoyl-L-aspartate to 4,5-dihydroorotate. De novo pyrimidine biosynthesis pathway, overview
metabolism
the de novo pyrimidine biosynthesis pathway is essential for the proliferation of many pathogens. One of the pathway enzymes, dihydroorotase (DHO), catalyzes the reversible interconversion of N-carbamoyl-L-aspartate to 4,5-dihydroorotate. De novo pyrimidine biosynthesis pathway, overview
metabolism
the dihydroorotase (DHOase) domain of the multifunctional protein carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase (CAD) catalyzes the third step in the de novo biosynthesis of pyrimidine nucleotides in animals
metabolism
Leishmania donovani BHU 1081
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de novo pyrimidine biosynthesis pathway is well developed and functional in protozoan parasite Leishmania donovani. The dihydroorotase (LdDHOase) is the third enzyme of the pathway
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metabolism
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the de novo pyrimidine biosynthesis pathway is essential for the proliferation of many pathogens. One of the pathway enzymes, dihydroorotase (DHO), catalyzes the reversible interconversion of N-carbamoyl-L-aspartate to 4,5-dihydroorotate. De novo pyrimidine biosynthesis pathway, overview
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metabolism
Methanocaldococcus jannaschii ATCC 624773
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catalyzes the conversion of N-carbamoyl-L-aspartate to dihydroorotate in the third step of the de novo biosynthesis of pyrimidines
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metabolism
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third enzyme in the bacterial de novo pyrimidine biosynthesis pathway, overview
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metabolism
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the de novo pyrimidine biosynthesis pathway is essential for the proliferation of many pathogens. One of the pathway enzymes, dihydroorotase (DHO), catalyzes the reversible interconversion of N-carbamoyl-L-aspartate to 4,5-dihydroorotate. De novo pyrimidine biosynthesis pathway, overview
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following pyrimidine limitation of orotidine 5'-monophosphate decarboxylase mutant strain cells, dihydroorotase and dihydroorotate dehydrogenase activities double while aspartate transcarbamoylase and orotate phosphoribosyltransferase activities are slightly elevated compared to their activities in the mutant strain cells grown on excess uracil
physiological function
cells rely on nucleotide synthesis for survival and proliferation, and pyrimidines are essential building blocks of RNA and DNA. Dihydroorotase (DHOase), the third enzyme in the essential de novo pyrimidine pathway, is responsible for the reversible cyclization of carbamyl-asparate (Ca-asp) to dihydroorotate (DHO)
physiological function
the enzyme catalyzes the reversible cyclization of N-carbamyl aspartate to dihydroorotate
physiological function
Leishmania donovani BHU 1081
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the enzyme catalyzes the reversible cyclization of N-carbamyl aspartate to dihydroorotate
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physiological function
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cells rely on nucleotide synthesis for survival and proliferation, and pyrimidines are essential building blocks of RNA and DNA. Dihydroorotase (DHOase), the third enzyme in the essential de novo pyrimidine pathway, is responsible for the reversible cyclization of carbamyl-asparate (Ca-asp) to dihydroorotate (DHO)
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additional information
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the enzyme contains four histidine, one aspartate, and one post-carboxylated lysine residue, which are required for metal binding and catalytic activity
additional information
analysis of the catalytic flexible loop in the dihydroorotase domain of the human multi-enzymatic protein CAD, molecular dynamics simulations, overview. Residue Phe1563, a residue absolutely conserved at the tip of the flexible loop in CAD's DHOase domain, is a critical element for the conformational equilibrium between the two catalytic states of the protein. Key role of Phe-1563 in configuring the active site and in promoting substrate strain and catalysis. The flexible loop reaches in toward the active site with N-carbamoyl-L-aspartate bound and is proposed to aid in catalysis by orienting and increasing the electrophilicity of the substrate, excluding water molecules, and stabilizing the transition-state. Then, upon the formation of DHO, the loop moves away from the active site, facilitating product release. As an exception, bacterial type I DHOases present a rigid and shorter loop that interacts minimally with the substrate, requiring the intimate association with ATCase to complete the active site and attain full activity
additional information
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analysis of the catalytic flexible loop in the dihydroorotase domain of the human multi-enzymatic protein CAD, molecular dynamics simulations, overview. Residue Phe1563, a residue absolutely conserved at the tip of the flexible loop in CAD's DHOase domain, is a critical element for the conformational equilibrium between the two catalytic states of the protein. Key role of Phe-1563 in configuring the active site and in promoting substrate strain and catalysis. The flexible loop reaches in toward the active site with N-carbamoyl-L-aspartate bound and is proposed to aid in catalysis by orienting and increasing the electrophilicity of the substrate, excluding water molecules, and stabilizing the transition-state. Then, upon the formation of DHO, the loop moves away from the active site, facilitating product release. As an exception, bacterial type I DHOases present a rigid and shorter loop that interacts minimally with the substrate, requiring the intimate association with ATCase to complete the active site and attain full activity
additional information
homology modeling of LdDHOase showing the active site residues, overview
additional information
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homology modeling of LdDHOase showing the active site residues, overview
additional information
in the hyperthermophilic bacterium Aquifex aeolicus, aspartate transcarbamylase (ATCase, EC 2.1.3.2) and dihydroorotase (DHOase) are noncovalently associated. Upon dissociation, ATCase keeps its activity entirely while DHOase is totally inactivated. High pressure fully restores the activity of this isolated DHOase. Under high-hydrostatic pressure, at 600 bar, and to a greater extent at 1200 bar, the orthorhombic form of DHOase displays a structure, which includes the Cys-181 bridge of the C2-ap form and some additional residues of the missing loops that become ordered and visible in the electron density
additional information
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in the hyperthermophilic bacterium Aquifex aeolicus, aspartate transcarbamylase (ATCase, EC 2.1.3.2) and dihydroorotase (DHOase) are noncovalently associated. Upon dissociation, ATCase keeps its activity entirely while DHOase is totally inactivated. High pressure fully restores the activity of this isolated DHOase. Under high-hydrostatic pressure, at 600 bar, and to a greater extent at 1200 bar, the orthorhombic form of DHOase displays a structure, which includes the Cys-181 bridge of the C2-ap form and some additional residues of the missing loops that become ordered and visible in the electron density
additional information
structure homology modelling using the Plasmodium falciparum enzyme structure as model (PfDHO, UniProtKB ID Q8IKA9)
additional information
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structure homology modelling using the Plasmodium falciparum enzyme structure as model (PfDHO, UniProtKB ID Q8IKA9)
additional information
structure homology modelling using the Plasmodium falciparum enzyme structure as model (PfDHO,UniProtKB ID Q8IKA9)
additional information
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structure homology modelling using the structure of DHOase from Methanocaldococcus jannaschii strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440, UniProt ID Q58885. Sequence and structure comparisons
additional information
the isolated DHO protein, a 45-kDa monomer, lacks catalytic activity but becomes active upon formation of a dodecameric complex with aspartate transcarbamoylase (ATC, EC 2.1.3.2). In the isolated DHO, a flexible loop occludes the active site blocking the access of substrates. The loop is mostly disordered but is tethered to the active site region by several electrostatic and hydrogen bonds. This loop becomes ordered and is displaced from the active site upon formation of DHO-ATC complex. The application of pressure to the complex causes its time-dependent dissociation and the loss of both DHO and ATC activities. Pressure induces irreversible dissociation of the obligate ATC trimer, and as a consequence the DHO is also inactivated
additional information
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the isolated DHO protein, a 45-kDa monomer, lacks catalytic activity but becomes active upon formation of a dodecameric complex with aspartate transcarbamoylase (ATC, EC 2.1.3.2). In the isolated DHO, a flexible loop occludes the active site blocking the access of substrates. The loop is mostly disordered but is tethered to the active site region by several electrostatic and hydrogen bonds. This loop becomes ordered and is displaced from the active site upon formation of DHO-ATC complex. The application of pressure to the complex causes its time-dependent dissociation and the loss of both DHO and ATC activities. Pressure induces irreversible dissociation of the obligate ATC trimer, and as a consequence the DHO is also inactivated
additional information
the two Zn2+ ions hold the substrate Ca-asp in position along with the active site residues, Arg60, Asn93, and His308, which also overlap well, suggesting the substrate is stabilized by the same hydrogen bond interactions. The hydrogen bond interaction between Ca-asp and the two threonine on the catalytic loop play a crucial role in Class II enzymes, but neither of the threonine residues is present in Bacillus anthracis DHOase, structure analysis reveals that glycine (G152) in the shorter Class I loop serves this function. Catalytic mechanism, overview
additional information
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the two Zn2+ ions hold the substrate Ca-asp in position along with the active site residues, Arg60, Asn93, and His308, which also overlap well, suggesting the substrate is stabilized by the same hydrogen bond interactions. The hydrogen bond interaction between Ca-asp and the two threonine on the catalytic loop play a crucial role in Class II enzymes, but neither of the threonine residues is present in Bacillus anthracis DHOase, structure analysis reveals that glycine (G152) in the shorter Class I loop serves this function. Catalytic mechanism, overview
additional information
Leishmania donovani BHU 1081
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homology modeling of LdDHOase showing the active site residues, overview
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additional information
-
the two Zn2+ ions hold the substrate Ca-asp in position along with the active site residues, Arg60, Asn93, and His308, which also overlap well, suggesting the substrate is stabilized by the same hydrogen bond interactions. The hydrogen bond interaction between Ca-asp and the two threonine on the catalytic loop play a crucial role in Class II enzymes, but neither of the threonine residues is present in Bacillus anthracis DHOase, structure analysis reveals that glycine (G152) in the shorter Class I loop serves this function. Catalytic mechanism, overview
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additional information
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structure homology modelling using the Plasmodium falciparum enzyme structure as model (PfDHO,UniProtKB ID Q8IKA9)
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additional information
Methanocaldococcus jannaschii ATCC 624773
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structure homology modelling using the structure of DHOase from Methanocaldococcus jannaschii strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440, UniProt ID Q58885. Sequence and structure comparisons
-
additional information
-
structure homology modelling using the Plasmodium falciparum enzyme structure as model (PfDHO,UniProtKB ID Q8IKA9)
-