Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization
In humans, the phosphorylated pathway (PP) converts the glycolytic intermediate D-3-phosphoglycerate (3-PG) into L-serine through the enzymes 3-phosphoglycerate dehydrogenase, phosphoserine aminotransferase (PSAT) and phosphoserine phosphatase. From the pathogenic point of view, the PP in the brain...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-08-01
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| Series: | Biomolecules |
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| Online Access: | https://www.mdpi.com/2218-273X/13/8/1219 |
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| author | Francesco Marchesani Annalisa Michielon Elisabetta Viale Annalisa Bianchera Davide Cavazzini Loredano Pollegioni Giulia Murtas Andrea Mozzarelli Stefano Bettati Alessio Peracchi Barbara Campanini Stefano Bruno |
| author_facet | Francesco Marchesani Annalisa Michielon Elisabetta Viale Annalisa Bianchera Davide Cavazzini Loredano Pollegioni Giulia Murtas Andrea Mozzarelli Stefano Bettati Alessio Peracchi Barbara Campanini Stefano Bruno |
| author_sort | Francesco Marchesani |
| collection | DOAJ |
| description | In humans, the phosphorylated pathway (PP) converts the glycolytic intermediate D-3-phosphoglycerate (3-PG) into L-serine through the enzymes 3-phosphoglycerate dehydrogenase, phosphoserine aminotransferase (PSAT) and phosphoserine phosphatase. From the pathogenic point of view, the PP in the brain is particularly relevant, as genetic defects of any of the three enzymes are associated with a group of neurometabolic disorders known as serine deficiency disorders (SDDs). We recombinantly expressed and characterized eight variants of PSAT associated with SDDs and two non-SDD associated variants. We show that the pathogenetic mechanisms in SDDs are extremely diverse, including low affinity of the cofactor pyridoxal 5′-phosphate and thermal instability for S179L and G79W PSAT, loss of activity of the holo form for R342W PSAT, aggregation for D100A PSAT, increased K<sub>m</sub> for one of the substrates with invariant k<sub>cat</sub>s for S43R PSAT, and a combination of increased K<sub>m</sub> and decreased k<sub>cat</sub> for C245R PSAT. Finally, we show that the flux through the in vitro reconstructed PP at physiological concentrations of substrates and enzymes is extremely sensitive to alterations of the functional properties of PSAT variants, confirming PSAT dysfunctions as a cause of SSDs. |
| first_indexed | 2024-03-11T00:05:53Z |
| format | Article |
| id | doaj.art-e648a56512b64d6781a6597db3b02d24 |
| institution | Directory Open Access Journal |
| issn | 2218-273X |
| language | English |
| last_indexed | 2024-03-11T00:05:53Z |
| publishDate | 2023-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Biomolecules |
| spelling | doaj.art-e648a56512b64d6781a6597db3b02d242023-11-19T00:23:54ZengMDPI AGBiomolecules2218-273X2023-08-01138121910.3390/biom13081219Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional CharacterizationFrancesco Marchesani0Annalisa Michielon1Elisabetta Viale2Annalisa Bianchera3Davide Cavazzini4Loredano Pollegioni5Giulia Murtas6Andrea Mozzarelli7Stefano Bettati8Alessio Peracchi9Barbara Campanini10Stefano Bruno11Department of Medicine and Surgery, University of Parma, 43124 Parma, ItalyDepartment of Food and Drug, University of Parma, 43124 Parma, ItalyBiopharmanet-TEC, University of Parma, 43124 Parma, ItalyDepartment of Food and Drug, University of Parma, 43124 Parma, ItalyDepartment of Chemistry/Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, ItalyThe Protein Factory 2.0, Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, ItalyThe Protein Factory 2.0, Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, ItalyInstitute of Biophysics, CNR, 56124 Pisa, ItalyDepartment of Medicine and Surgery, University of Parma, 43124 Parma, ItalyDepartment of Chemistry/Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, ItalyDepartment of Food and Drug, University of Parma, 43124 Parma, ItalyDepartment of Food and Drug, University of Parma, 43124 Parma, ItalyIn humans, the phosphorylated pathway (PP) converts the glycolytic intermediate D-3-phosphoglycerate (3-PG) into L-serine through the enzymes 3-phosphoglycerate dehydrogenase, phosphoserine aminotransferase (PSAT) and phosphoserine phosphatase. From the pathogenic point of view, the PP in the brain is particularly relevant, as genetic defects of any of the three enzymes are associated with a group of neurometabolic disorders known as serine deficiency disorders (SDDs). We recombinantly expressed and characterized eight variants of PSAT associated with SDDs and two non-SDD associated variants. We show that the pathogenetic mechanisms in SDDs are extremely diverse, including low affinity of the cofactor pyridoxal 5′-phosphate and thermal instability for S179L and G79W PSAT, loss of activity of the holo form for R342W PSAT, aggregation for D100A PSAT, increased K<sub>m</sub> for one of the substrates with invariant k<sub>cat</sub>s for S43R PSAT, and a combination of increased K<sub>m</sub> and decreased k<sub>cat</sub> for C245R PSAT. Finally, we show that the flux through the in vitro reconstructed PP at physiological concentrations of substrates and enzymes is extremely sensitive to alterations of the functional properties of PSAT variants, confirming PSAT dysfunctions as a cause of SSDs.https://www.mdpi.com/2218-273X/13/8/1219phosphorylated pathwayserine deficiency disordersphosphoserine aminotransferaseNeu–Laxova syndromeneurometabolic disorders |
| spellingShingle | Francesco Marchesani Annalisa Michielon Elisabetta Viale Annalisa Bianchera Davide Cavazzini Loredano Pollegioni Giulia Murtas Andrea Mozzarelli Stefano Bettati Alessio Peracchi Barbara Campanini Stefano Bruno Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization Biomolecules phosphorylated pathway serine deficiency disorders phosphoserine aminotransferase Neu–Laxova syndrome neurometabolic disorders |
| title | Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization |
| title_full | Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization |
| title_fullStr | Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization |
| title_full_unstemmed | Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization |
| title_short | Phosphoserine Aminotransferase Pathogenetic Variants in Serine Deficiency Disorders: A Functional Characterization |
| title_sort | phosphoserine aminotransferase pathogenetic variants in serine deficiency disorders a functional characterization |
| topic | phosphorylated pathway serine deficiency disorders phosphoserine aminotransferase Neu–Laxova syndrome neurometabolic disorders |
| url | https://www.mdpi.com/2218-273X/13/8/1219 |
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