Dataset Information

Glutathione Non-Covalent Binding Sites on Hemoglobin and Major Glutathionylation Target betaCys93 Are Conservative among Both Hypoxia-Sensitive and Hypoxia-Tolerant Mammal Species.

ABSTRACT: Intracellular tripeptide glutathione is an important agent of cell survival under hypoxia. Glutathione covalently binds to SH groups of hemoglobin cysteine residues, protecting them from irreversible oxidation, and changes its affinity to oxygen. Reduced glutathione (GSH) can also form a noncovalent complex with hemoglobin. Previously, we showed that hemoglobin tetramer has four noncovalent binding sites of glutathione GSH molecules inside, two of which are released during hemoglobin transition to deoxy form. In this study, we characterized the conserved cysteine residues and residues of noncovalent glutathione binding sites in the sequences of a number of hypoxia-tolerant and hypoxia-sensitive mammals. The solvent accessibility of all HbA and HbB residues in oxy and deoxy forms was analyzed. The alpha subunit of all species considered was shown to have no conserved cysteines, whereas the beta subunit contains Cys93 residue, which is conserved across species and whose glutathionylation changes the affinity of hemoglobin for oxygen 5-6-fold. It was found that the key residues of noncovalent glutathione binding sites in both alpha and beta subunits are absolutely conserved in all species considered, suggesting a common mechanism of hemoglobin redox regulation for both hypoxia-sensitive and hypoxia-tolerant mammals.

SUBMITTER: Anashkina AA

PROVIDER: S-EPMC10778717 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Glutathione Non-Covalent Binding Sites on Hemoglobin and Major Glutathionylation Target betaCys93 Are Conservative among Both Hypoxia-Sensitive and Hypoxia-Tolerant Mammal Species.

Anashkina Anastasia A AA Simonenko Sergey Yu SY Orlov Yuriy L YL Petrushanko Irina Yu IY

International journal of molecular sciences 20231219 1

Intracellular tripeptide glutathione is an important agent of cell survival under hypoxia. Glutathione covalently binds to SH groups of hemoglobin cysteine residues, protecting them from irreversible oxidation, and changes its affinity to oxygen. Reduced glutathione (GSH) can also form a noncovalent complex with hemoglobin. Previously, we showed that hemoglobin tetramer has four noncovalent binding sites of glutathione GSH molecules inside, two of which are released during hemoglobin transition ...[more]

PMID: 38203223

Similar Datasets

Project description:BackgroundFlexibility of plant metabolism is supported by redox regulation of enzymes via posttranslational modification of cysteine residues, especially in plastids. Here, the redox states of cysteine residues are partly coupled to the thioredoxin system and partly to the glutathione pool for reduction. Moreover, several plastid enzymes involved in reactive oxygen species (ROS) scavenging and damage repair draw electrons from glutathione. In addition, cysteine residues can be post-translationally modified by forming a mixed disulfide with glutathione (S-glutathionylation), which protects thiol groups from further oxidation and can influence protein activity. However, the evolution of the plastid glutathione-dependent redox network in land plants and the conservation of cysteine residues undergoing S-glutathionylation is largely unclear.ResultsWe analysed the genomes of nine representative model species from streptophyte algae to angiosperms and found that the antioxidant enzymes and redox proteins belonging to the plastid glutathione-dependent redox network are largely conserved, except for lambda- and the closely related iota-glutathione S-transferases. Focussing on glutathione-dependent redox modifications, we screened the literature for target thiols of S-glutathionylation, and found that 151 plastid proteins have been identified as glutathionylation targets, while the exact cysteine residue is only known for 17% (26 proteins), with one or multiple sites per protein, resulting in 37 known S-glutathionylation sites for plastids. However, 38% (14) of the known sites were completely conserved in model species from green algae to flowering plants, with 22% (8) on non-catalytic cysteines. Variable conservation of the remaining sites indicates independent gains and losses of cysteines at the same position during land plant evolution.ConclusionsWe conclude that the glutathione-dependent redox network in plastids is highly conserved in streptophytes with some variability in scavenging and damage repair enzymes. Our analysis of cysteine conservation suggests that S-glutathionylation in plastids plays an important and yet under-investigated role in redox regulation and stress response.

Project description:Mutp53 level is widely variable among individual cancer cells in tumor tissues, and within cells a higher level of mutp53 is usually observed in the nucleus as compared to the cytoplasm. This spatial heterogeneity in mutp53 expression has been well documented and likely plays an important role in tumor therapeutic resistance. However, its underlying mechanism remains poorly understood. In this study, we first revealed a critical role of micro-environmental reducing status in regulating mutp53 stability and spatially heterogeneous accumulation. Immunofluorescence and ThiolTracker Violet dye staining demonstrated a clear correlation between the cellular mutp53 level and the reducibility in the patient-derived tumor tissues and mutp53-expressing cancer cell lines. The nucleus exhibited both higher reducibility and more mutp53 accumulation than the cytoplasm did. Supplementing GSH exacerbated the accumulation of mutp53, while consuming GSH led to extensive depletion of mutp53, suggesting that the environmental reducing status kept mutp53 stability. Mechanistically, S-glutathionylation could trigger ubiquitination and proteasomal degradation of mutp53. A highly-reducing local environment preserved mutp53 stability by inhibiting glutathionylation and subsequent proteasomal degradation of mutp53, which also provided an explanation for the differential accumulation of mutp53 proteins in the nucleus and cytoplasm. Thirdly, we revealed that the expression level of glutathione reductase (GR) was positively correlated with mutp53 accumulation across the cultured mutp53-expressing cell lines, patient-derived tumor tissues and patient databases. Over-expression of GR reinforced the environmental reducibility, affected glutathionylation and improved mutp53 accumulation, while inhibiting GR either by chemical inhibitors or genetic approach induced massive clearance of a variety of mutp53 and effectively retarded the growth of p53-mutated cell-derived xenografts in mice. These studies provided an explanation for the widely-observed spatial heterogeneous accumulation of mutp53 proteins, and inhibiting GR or directly consuming GSH represented a promising strategy for mutp53 carrying cancer therapy.

Dataset Information

Glutathione Non-Covalent Binding Sites on Hemoglobin and Major Glutathionylation Target betaCys93 Are Conservative among Both Hypoxia-Sensitive and Hypoxia-Tolerant Mammal Species.

Publications

Glutathione Non-Covalent Binding Sites on Hemoglobin and Major Glutathionylation Target betaCys93 Are Conservative among Both Hypoxia-Sensitive and Hypoxia-Tolerant Mammal Species.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets