Molecular Characterization, Protein–Protein Interaction Network, and Evolution of Four Glutathione Peroxidases from Tetrahymena thermophila

Abstract

Glutathione peroxidases (GPxs) form a broad family of antioxidant proteins essential for maintaining redox homeostasis in eukaryotic cells. In this study, we used an integrative approach that combines bioinformatics, molecular biology, and biochemistry to investigate the role of GPxs in reactive oxygen species detoxification in the unicellular eukaryotic model organism Tetrahymena thermophila. Both phylogenetic and mechanistic empirical model analyses provided indications about the evolutionary relationships among the GPXs of Tetrahymena and the orthologous enzymes of phylogenetically related species. In-silico gene characterization and text mining were used to predict the functional relationships between GPxs and other physiologically-relevant processes. The GPx genes contain conserved transcriptional regulatory elements in the promoter region, which suggest that transcription is under tight control of specialized signaling pathways. The bioinformatic findings were next experimentally validated by studying the time course of gene transcription and enzymatic activity after copper (Cu) exposure. Results emphasize the role of GPxs in the detoxification pathways that, by complex regulation of GPx gene expression, enable Tethraymena to survive in high Cu concentrations and the associated redox environment.

PFAS Environmental Pollution and Antioxidant Responses: An Overview of the Impact on Human Field

“…It is interesting to note that often the enzymatic activities of CAT and GPx are inversely correlated. This has a physiological significance, as both enzymes target H 2 O 2 , and therefore they can play a complementary role within the antioxidant system, ensuring adequate protection of the cell against the negative effects of inorganic and organic peroxides [326].…”

PFAS Environmental Pollution and Antioxidant Responses: An Overview of the Impact on Human Field

“…It is interesting to note that often the enzymatic activities of CAT and GPx are inversely correlated. This has a physiological significance, as both enzymes target H2O2, and therefore they can play a complementary role within the antioxidant system, ensuring adequate protection of the cell against the negative effects of inorganic and organic peroxides [323].…”

Typical 2-Cys Peroxiredoxins as a Defense Mechanism against Metal-Induced Oxidative Stress in the Solitary Ascidian <em>Ciona robusta</em>

“…As regards the phylogenetic analyzes performed on the amino acid sequences, cladograms were obtained which show a practically identical topology to that of the cladograms obtained with the nucleotide sequences, despite a lower degree of resolution. This result is in line with the high degree of conservation of amino acid sequences and could be the result of a strong purifying selection acting on them, an evolutionary feature common to other genes encoding antioxidant enzymes [16,17,19,51,52]. The action of purifying selection is important for the evolution of gene families, as it guarantees the maintenance of function of the encoded proteins.…”