2.6.1.52: phosphoserine transaminase
This is an abbreviated version!
For detailed information about phosphoserine transaminase, go to the full flat file.
Reaction
Synonyms
3-O-phospho-L-serine:2-oxoglutarate aminotransferase, 3-phosphoserine aminotransferase, AspAT, AtPSAT, AtPSAT1, BCIR PSAT, bmPSAT, EhPSAT, hydroxypyruvic phosphate-glutamic transaminase, L-phosphoserine aminotransferase, phosphohydroxypyruvate transaminase, phosphohydroxypyruvic-glutamic transaminase, phosphoserine aminotransferase, phosphoserine aminotransferase 1, phosphoserine aminotransferase1, phosphoserine aminotransferase2, phosphoserine aminotransferases, PSAT, PSAT alpha, PSAT beta, PSAT-BALC, PSAT-BCIRA, PSAT-ECOLI, PSAT1, PSAT2, PSerAT, serC, sll1559
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General Information
General Information on EC 2.6.1.52 - phosphoserine transaminase
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evolution
malfunction
metabolism
physiological function
additional information
phosphoserine aminotransferases belong to the class IV of aminotransferases with the alpha-type fold. In general, this class of enzymes is characterized by the presence of two domains with mixed alpha/beta fold
evolution
the Arabidopsis genome contains three genes for the PGDH (At4g34200/PGDH1, At1g17745/ PGDH2, and At3g19480/ PGDH3), two genes for the PSAT (At4g35630/PSAT1, and At2g17630/PSAT2) and one gene for the PSP (At1g18640). The PSAT1 gene is the most expressed isoform in Arabidopsis thaliana
a growth phenotype is observed for PSAT1-silenced plants due to serine deficiency
malfunction
a sericin-deficient silkworm strain exhibits a diminished expression of bmPSAT mRNA in the silk gland
malfunction
deletion of 45 N-terminal residues (EhPSAT_DELTA45) results in an inactive protein, the structure shows a dimeric arrangement drastically different from that of the wild-type protein
malfunction
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a sericin-deficient silkworm strain exhibits a diminished expression of bmPSAT mRNA in the silk gland
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malfunction
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deletion of 45 N-terminal residues (EhPSAT_DELTA45) results in an inactive protein, the structure shows a dimeric arrangement drastically different from that of the wild-type protein
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malfunction
Bombyx mori b94
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a sericin-deficient silkworm strain exhibits a diminished expression of bmPSAT mRNA in the silk gland
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enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
enzyme PSAT catalyses the second step of phosphorylated pathway of serine biosynthesis
metabolism
L-serine is involved in several important metabolic pathways in the protozoan parasite Entamoeba histolytica. Phosphoserine aminotransferase (PSAT) is a pyridoxal-5'phosphate (PLP)-dependent enzyme that catalyzes the second reversible step in the phosphoserine biosynthetic pathway producing L-serine
metabolism
phosphoserine aminotransferase (bmPSAT) from Bombyx mori is responsible for L-serine biosynthesis. This pathway composed of D-3-phosphoglycerate dehydrogenase (EC 1.1.1.95), PSAT, and phosphoserine phosphatase (PSP, EC 3.1.3.3) is crucial for the de novo production of L-serine from a glycolytic intermediate, 3-phosphoglycerate
metabolism
phosphoserine aminotransferase (PSAT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the conversion of 3-phosphohydroxypyruvate (3-PHP) to 3-phosphoserine (PSer) in an L-glutamate (Glu)-linked reversible transamination reaction. This process in plants takes place in plastids. It is a part of the phosphorylated pathway of serine biosynthesis, one of three routes recognized in plant organisms that yield serine. In this three-step biotransformation, 3-phosphoglycerate (3-PGA) delivered from plastidial glycolysis and Calvin cycle is oxidized by 3-PGA dehydrogenase. Then, 3-PHP is subjected to transamination with Glu to yield PSer and 2-oxoglutarate (AKG). In the last step of the pathway, serine is produced by the action of phosphoserine phosphatase
metabolism
the serine biosynthesis pathway consists of three sequential reactions that are catalyzed by 3-phosphoglycerate dehydrogenase (PGDH), 3-phosphoserine aminotransferase (PSAT), and 3-phosphoserine phosphatase (PSP) enzymes, all localized in the plastids. Serine biosynthesis pathways in plants, overview
metabolism
transcriptional regulators TAZ and YAP (TAZ/YAP) promote glutamine dependence in breast cancer cells and activate the expression of glutamine-utilizing transaminases to support cell growth. TAZ and YAP induce glutamic-oxaloacetic transaminase (GOT1, EC 2.6.1.64) and phosphoserine aminotransferase (PSAT1) expression. Transcriptional regulators TAZ/YAP activity positively correlates with transaminase expression in breast cancer patients, while transaminase inhibitor aminooxyacetate (AOA) represses cell growth in a TAZ/YAP-dependent manner. Thus, transamination is a potential vulnerable metabolic requirement for TAZ/YAP-driven breast cancer
metabolism
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phosphoserine aminotransferase (bmPSAT) from Bombyx mori is responsible for L-serine biosynthesis. This pathway composed of D-3-phosphoglycerate dehydrogenase (EC 1.1.1.95), PSAT, and phosphoserine phosphatase (PSP, EC 3.1.3.3) is crucial for the de novo production of L-serine from a glycolytic intermediate, 3-phosphoglycerate
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metabolism
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L-serine is involved in several important metabolic pathways in the protozoan parasite Entamoeba histolytica. Phosphoserine aminotransferase (PSAT) is a pyridoxal-5'phosphate (PLP)-dependent enzyme that catalyzes the second reversible step in the phosphoserine biosynthetic pathway producing L-serine
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metabolism
Bombyx mori b94
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phosphoserine aminotransferase (bmPSAT) from Bombyx mori is responsible for L-serine biosynthesis. This pathway composed of D-3-phosphoglycerate dehydrogenase (EC 1.1.1.95), PSAT, and phosphoserine phosphatase (PSP, EC 3.1.3.3) is crucial for the de novo production of L-serine from a glycolytic intermediate, 3-phosphoglycerate
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enzyme forms a protein-protein complex with D-phosphoglycerate dehydrogenase, which has a 1:1 stoichiometry. Ionic interactions play a significant role in complex formation and stability. The nucleotide binding domain of D-phosphoglycerate dehydrogenase specifically interacts with the enzyme. The purified nucleotide binding domain of D-phosphoglycerate dehydrogenase interacts with phosphoserine transaminase. The reactions catalyzed by the complex suggest a possibility of substrate channelling in the protein complex
physiological function
enzyme is part of the phosphoserine pathway for serine synthesis. A model approach indicates a 3060% contribution of the phosphoserine pathway to the overall serine pool
physiological function
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hepatic PSAT1 expression and liver serine levels are reduced in genetically engineered leptin receptor-deficient (db/db) mice and high-fat diet (HFD)-induced diabetic mice. Overexpression of PSAT1 by adenovirus expressing PSAT1 improves insulin signaling and insulin sensitivity in vitro and in vivo under normal conditions. Opposite effects are observed when PSAT1 is knocked down by small hairpin RNA specific for PSAT1. Overexpression of PSAT1 also significantly ameliorates insulin resistance in diabetic mice. PSAT1 inhibits the expression of hepatic tribbles homolog TRB3 in vitro and in vivo. Serine mediates PSAT1 regulation of TRB3 expression and insulin signaling in vitro
physiological function
analysis of association of PSAT1 protein levels upon tamoxifen treatment and enzyme role in tamoxifen resistance, PSAT1 protein and mRNA levels are significantly associated to poor outcome to tamoxifen treatment. Cytokine and JAK-STAT signaling are associated with PSAT1 expression. Clinical significance of PSAT1 in the gene expression cohort and pathway analysis
physiological function
phosphoserine aminotransferase (bmPSAT) from Bombyx mori is responsible for L-serine biosynthesis. bmPSAT may play an important role in synthesizing and supplying L-serine in the larva of Bombyx mori. The silk gland is the sole organ in which silk is synthesized and secreted in the silkworm. Silk is composed of two types of proteins: sericin and fibroin, both of which contain high levels of L-serine and glycine
physiological function
phosphoserine aminotransferase1 is part of the phosphorylated pathways for serine biosynthesis and essential for light and sugar-dependent growth promotion
physiological function
-
phosphoserine aminotransferase (bmPSAT) from Bombyx mori is responsible for L-serine biosynthesis. bmPSAT may play an important role in synthesizing and supplying L-serine in the larva of Bombyx mori. The silk gland is the sole organ in which silk is synthesized and secreted in the silkworm. Silk is composed of two types of proteins: sericin and fibroin, both of which contain high levels of L-serine and glycine
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physiological function
Bombyx mori b94
-
phosphoserine aminotransferase (bmPSAT) from Bombyx mori is responsible for L-serine biosynthesis. bmPSAT may play an important role in synthesizing and supplying L-serine in the larva of Bombyx mori. The silk gland is the sole organ in which silk is synthesized and secreted in the silkworm. Silk is composed of two types of proteins: sericin and fibroin, both of which contain high levels of L-serine and glycine
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conformational changes of the protein during the catalytic event concern (i) the neighborhood of K265 when the amino group is transferred to the cofactor to form PMP and (ii) movement of the gate-keeping loop (residues 391-401) upon binding of of 3-phosphohydroxypyruvate to 3-phosphoserine. The latter conformational change of the loop may likely be one of key elements that regulate catalytic activity of PSATs. The conserved catalytic lysine, which directly follows a hydrophobic beta-strand, is localized closer to the C-terminus than the Gly-rich region. PSATs have an aspartate residue which hydrogen bonds the pyridoxal ring N1 atom and precedes the Schiff base lysine by 20-50 amino acids. The complex structure with pyridoxamine shows the enzyme primes for a covalent binding of 3-phosphohydroxypyruvate. The complex structure with phopshoserine reveals the geminal diamine intermediate state
additional information
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conformational changes of the protein during the catalytic event concern (i) the neighborhood of K265 when the amino group is transferred to the cofactor to form PMP and (ii) movement of the gate-keeping loop (residues 391-401) upon binding of of 3-phosphohydroxypyruvate to 3-phosphoserine. The latter conformational change of the loop may likely be one of key elements that regulate catalytic activity of PSATs. The conserved catalytic lysine, which directly follows a hydrophobic beta-strand, is localized closer to the C-terminus than the Gly-rich region. PSATs have an aspartate residue which hydrogen bonds the pyridoxal ring N1 atom and precedes the Schiff base lysine by 20-50 amino acids. The complex structure with pyridoxamine shows the enzyme primes for a covalent binding of 3-phosphohydroxypyruvate. The complex structure with phopshoserine reveals the geminal diamine intermediate state