Search results for "Phosphoserine"
showing 10 items of 12 documents
Phosphoglycerate dehydrogenase genes differentially affect Arabidopsis metabolism and development.
2021
[EN] Unlike animals, plants possess diverse L-serine (Ser) biosynthetic pathways. One of them, the Phosphorylated Pathway of Serine Biosynthesis (PPSB) has been recently described as essential for embryo, pollen and root development, and required for ammonium and sulfur assimilation. The first and rate limiting step of PPSB is the reaction catalyzed by the enzyme phosphoglycerate dehydrogenase (PGDH). In Arabidopsis, the PGDH family consists of three genes, PGDH1, PGDH2 and PGDH3. PGDH1 is characterized as being the essential gene of the family. However, the biological significance of PGDH2 and PGDH3 remains unknown. In this manuscript, we have functionally characterized PGDH2 and PGDH3. Ph…
Apoptotic Activity of MeCP2 Is Enhanced by C-Terminal Truncating Mutations.
2016
Methyl-CpG binding protein 2 (MeCP2) is a widely abundant, multifunctional protein most highly expressed in post-mitotic neurons. Mutations causing Rett syndrome and related neurodevelopmental disorders have been identified along the entire MECP2 locus, but symptoms vary depending on mutation type and location. C-terminal mutations are prevalent, but little is known about the function of the MeCP2 C-terminus. We employ the genetic efficiency of Drosophila to provide evidence that expression of p.Arg294* (more commonly identified as R294X), a human MECP2 E2 mutant allele causing truncation of the C-terminal domains, promotes apoptosis of identified neurons in vivo. We confirm this novel find…
Reverse screening on indicaxanthin from Opuntia ficus-indica as natural chemoactive and chemopreventive agent
2018
Indicaxanthin is a bioactive and bioavailable betalain pigment extracted from Opuntia ficus indica fruits. Indicaxanthin has pharmacokinetic proprieties, rarely found in other phytochemicals, and it has been demonstrated that it provides a broad-spectrum of pharmaceutical activity, exerting anti-proliferative, anti-inflammatory, and neuromodulator effects. The discovery of the Indicaxanthin physiological targets plays an important role in understanding the biochemical mechanism. In this study, combined reverse pharmacophore mapping, reverse docking, and text-based database search identified Inositol Trisphosphate 3-Kinase (ITP3K-A), Glutamate carboxypeptidase II (GCPII), Leukotriene-A4 hydr…
Structural Analysis of Phosphoserine Aminotransferase (Isoform 1) From Arabidopsis thaliana– the Enzyme Involved in the Phosphorylated Pathway of Ser…
2018
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 proceeds through a bimolecular ping-pong mechanism and 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 yi…
Phosphorylation of serine residues is fundamental for the calcium-binding ability of Orchestin, a soluble matrix protein from crustacean calcium stor…
2003
International audience; Orchestia cavimana is a terrestrial crustacean, which cyclically stores calcium in diverticula of the midgut, in the form of calcified amorphous concretions. These concretions are associated with a proteinaceous matrix, the main constituent of the soluble matrix is Orchestin, an acidic calcium-binding protein [Testenière et al., Biochem. J. 361 (2002) 327-335]. In the present paper, we clearly demonstrate that Orchestin is phosphorylated on serine and tyrosine residues, but that calcium binding only occurs via the phosphoserine residues. To our knowledge, this is the first example of an invertebrate mineralization for which a post-translational modification is clearl…
A novel regulatory mechanism of MAP kinases activation and nuclear translocation mediated by PKA and the PTP-SL tyrosine phosphatase
1999
Protein tyrosine phosphatase PTP-SL retains mitogen-activated protein (MAP) kinases in the cytoplasm in an inactive form by association through a kinase interaction motif (KIM) and tyrosine dephosphorylation. The related tyrosine phosphatases PTP-SL and STEP were phosphorylated by the cAMP-dependent protein kinase A (PKA). The PKA phosphorylation site on PTP-SL was identified as the Ser231 residue, located within the KIM. Upon phosphorylation of Ser231, PTP-SL binding and tyrosine dephosphorylation of the MAP kinases extracellular signal–regulated kinase (ERK)1/2 and p38α were impaired. Furthermore, treatment of COS-7 cells with PKA activators, or overexpression of the Cα catalytic subunit …
Lack of phosphoserine phosphatase activity alters pollen and tapetum development in Arabidopsis thaliana.
2015
Formation of mature pollen grain, an essential process for the reproduction of higher plants, is affected in lines that are deficient in the enzymes of the phosphorylated pathway of serine biosynthesis (PPSB). Mutants of phosphoserine phosphatase (PSP), the enzyme that catalyses the last step of PPSB, are embryo-lethal. When they are complemented with a construct carrying PSP1 cDNA under the control of the 35S promoter (psp1.1 35S:PSP1), which is poorly expressed in anther tissues, plants display a wild-type phenotype, but are male-sterile. The pollen from the psp1.1 35S:PSP1 lines are shrunken and unviable. Here we report the morphological alterations that appear in the psp1.1 35S:PSP1 lin…
Identification of the phosphoglycerate dehydrogenase isoform EDA9 as the essential gene for embryo and male gametophyte development in Arabidopsis
2013
[EN] Three different pathways of serine (Ser) biosynthesis have been described in plants: the Glycolate pathway, which is part of the Photorespiratory pathway, and 2 non-Photorespiratory pathways, the Glycerate and the Phosphorylated pathways. The Phosphorylated Pathway of Ser Biosynthesis (PPSB) has been known to exist since the 1950s, but its biological relevance was not revealed until quite recently when the last enzyme of the pathway, the Phosphoserine Phosphatase, was functionally characterized. In the associated study1, we characterized a family of genes coding for putatite phosphoglycerate dehydrogenases (PGDH, 3-PGDH, and EDA9), the first enzyme of the PPSB. A metabolomics study usi…
The essential role of the phosphorylated pathway of serine biosynthesis inArabidopsis
2013
[EN] In plants, 3 different pathways of serine biosynthesis have been described: the Glycolate pathway, which is associated with photorespiration, and 2 non-photorespiratory pathways, the Glycerate and the Phosphorylated pathways. The Phosphorylated Pathway of Serine Biosynthesis (PPSB) has been known since the 1950s, but has been studied relatively little, probably because it was considered of minor significance as compared with the Glycolate pathway. In the associated study1 , we described for the first time in plants the in vivo functional characterization of the PPSB, by targeting the phosphoserine phosphatase (PSP1), the last enzyme of the pathway. Following a gain—and loss-of-function…
The regulation mechanism for the auto-inhibition of binding of human filamin A to integrin.
2009
The ability of adhesion receptors to transmit biochemical signals and mechanical force across cell membranes depends on interactions with the actin cytoskeleton. Human filamins are large actin cross-linking proteins that connect integrins to the cytoskeleton. Filamin binding to the cytoplasmic tail of beta integrins has been shown to prevent integrin activation in cells, which is important for controlling cell adhesion and migration. The molecular-level mechanism for filamin binding to integrin has been unclear, however, as it was recently demonstrated that filamin undergoes intramolecular auto-inhibition of integrin binding. In this study, using steered molecular dynamics simulations, we f…