The allosteric interplay between S‐nitrosylation and glycine binding controls the activity of human serine racemase

Marchesani, Francesco; Gianquinto, Eleonora; Autiero, Ida; Michielon, Annalisa; Campanini, Barbara; Faggiano, Serena; Bettati, Stefano; Mozzarelli, Andrea; Spyrakis, Francesca; Bruno, Stefano

doi:10.1111/febs.15645

Cited by 10 publications

(9 citation statements)

References 72 publications

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“…As nitrosylation does not affect the apoprotein-FAD binding equilibrium ( Table 3 ), the observed effect is due to the easier reaction of GSNO with the cysteines of the apoprotein of hDAAO, a form which is known to possess a “relaxed” tertiary structure characterized by greater exposure of hydrophobic surfaces and increased sensitivity to chemical and thermal unfolding ( Caldinelli et al, 2009 ). Notably, S-nitrosylation of human SR affected its functionality by stabilizing an open, less-active conformation of the enzyme ( Marchesani et al, 2020 ). Thus, this reversible modification might represent a common mechanism for simultaneously controlling both D-Ser metabolic enzymes in different and neighboring cells.…”

Section: Discussionmentioning

confidence: 99%

Yin and Yang in Post-Translational Modifications of Human D-Amino Acid Oxidase

Sacchi

Rabattoni

Miceli

et al. 2021

Front. Mol. Biosci.

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In the central nervous system, the flavoprotein D-amino acid oxidase is responsible for catabolizing D-serine, the main endogenous coagonist of N-methyl-D-aspartate receptor. Dysregulation of D-serine brain levels in humans has been associated with neurodegenerative and psychiatric disorders. This D-amino acid is synthesized by the enzyme serine racemase, starting from the corresponding L-enantiomer, and degraded by both serine racemase (via an elimination reaction) and the flavoenzyme D-amino acid oxidase. To shed light on the role of human D-amino acid oxidase (hDAAO) in D-serine metabolism, the structural/functional relationships of this enzyme have been investigated in depth and several strategies aimed at controlling the enzymatic activity have been identified. Here, we focused on the effect of post-translational modifications: by using a combination of structural analyses, biochemical methods, and cellular studies, we investigated whether hDAAO is subjected to nitrosylation, sulfhydration, and phosphorylation. hDAAO is S-nitrosylated and this negatively affects its activity. In contrast, the hydrogen sulfide donor NaHS seems to alter the enzyme conformation, stabilizing a species with higher affinity for the flavin adenine dinucleotide cofactor and thus positively affecting enzymatic activity. Moreover, hDAAO is phosphorylated in cerebellum; however, the protein kinase involved is still unknown. Taken together, these findings indicate that D-serine levels can be also modulated by post-translational modifications of hDAAO as also known for the D-serine synthetic enzyme serine racemase.

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Section: Discussionmentioning

confidence: 99%

Yin and Yang in Post-Translational Modifications of Human D-Amino Acid Oxidase

Sacchi

Rabattoni

Miceli

et al. 2021

Front. Mol. Biosci.

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“…In the human CNS, the PP takes place in the astrocytes and the L-Ser thus produced is used locally or transported to neurons, where it can be converted to its enantiomer D-Ser by serine racemase. (Marchesani, Gianquinto, et al, 2021;Raboni et al, 2018) Human PSAT (EC 2.6.1.52) is a pyridoxal 5 0phosphate (PLP)-dependent enzyme whose coding gene is located on the long arm of chromosome 9. The primary gene transcript, and probably the only physiologically relevant one (Baek et al, 2003), codes for PSAT1 (or PSATβ).…”

Section: Introductionmentioning

confidence: 99%

L‐serine biosynthesis in the human central nervous system: Structure and function of phosphoserine aminotransferase

et al. 2023

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Organisms from all kingdoms of life synthesize L‐serine (L‐Ser) from 3‐phosphoglycerate through the phosphorylated pathway, a three‐step diversion of glycolysis. Phosphoserine aminotransferase (PSAT) catalyzes the intermediate step, the pyridoxal 5′‐phosphate‐dependent transamination of 3‐phosphohydroxypyruvate and L‐glutamate to O‐phosphoserine (OPS) and α‐ketoglutarate. PSAT is particularly relevant in the central nervous system of mammals because L‐Ser is the metabolic precursor of D‐serine, cysteine, phospholipids, and nucleotides. Several mutations in the human psat gene have been linked to serine deficiency disorders, characterized by severe neurological symptoms. Furthermore, PSAT is overexpressed in many tumors and this overexpression has been associated with poor clinical outcomes. Here, we report the detailed functional and structural characterization of the recombinant human PSAT. The reaction catalyzed by PSAT is reversible, with an equilibrium constant of about 10, and the enzyme is very efficient, with a kcat/Km of 5.9 × 106 M−1 s−1, thus contributing in driving the pathway towards the products despite the extremely unfavorable first step catalyzed by 3‐phosphoglycerate dehydrogenase. The 3D X‐ray crystal structure of PSAT was solved in the substrate‐free as well as in the OPS‐bound forms. Both structures contain eight protein molecules in the asymmetric unit, arranged in four dimers, with a bound cofactor in each subunit. In the substrate‐free form, the active site of PSAT contains a sulfate ion that, in the substrate‐bound form, is replaced by the phosphate group of OPS. Interestingly, fast crystal soaking used to produce the substrate‐bound form allowed the trapping of different intermediates along the catalytic cycle.

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“…The ability to lock the enzyme in the ‘open’ inactive state appears to be important in higher eukaryotes. S-nitrosylation of Cys 113 turns SR ‘off’ 51 – 53 . In the ‘open’ conformation Cys 113 is readily accessible (Fig.…”

Section: Resultsmentioning

confidence: 99%

Tyrosine 121 moves revealing a ligandable pocket that couples catalysis to ATP-binding in serine racemase

et al. 2022

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Human serine racemase (hSR) catalyses racemisation of L-serine to D-serine, the latter of which is a co-agonist of the NMDA subtype of glutamate receptors that are important in synaptic plasticity, learning and memory. In a ‘closed’ hSR structure containing the allosteric activator ATP, the inhibitor malonate is enclosed between the large and small domains while ATP is distal to the active site, residing at the dimer interface with the Tyr121 hydroxyl group contacting the α-phosphate of ATP. In contrast, in ‘open’ hSR structures, Tyr121 sits in the core of the small domain with its hydroxyl contacting the key catalytic residue Ser84. The ability to regulate SR activity by flipping Tyr121 from the core of the small domain to the dimer interface appears to have evolved in animals with a CNS. Multiple X-ray crystallographic enzyme-fragment structures show Tyr121 flipped out of its pocket in the core of the small domain. Data suggest that this ligandable pocket could be targeted by molecules that inhibit enzyme activity.

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The allosteric interplay between S‐nitrosylation and glycine binding controls the activity of human serine racemase

Cited by 10 publications

References 72 publications

Yin and Yang in Post-Translational Modifications of Human D-Amino Acid Oxidase

Yin and Yang in Post-Translational Modifications of Human D-Amino Acid Oxidase

L‐serine biosynthesis in the human central nervous system: Structure and function of phosphoserine aminotransferase

Tyrosine 121 moves revealing a ligandable pocket that couples catalysis to ATP-binding in serine racemase

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