Copper/Zinc Superoxide Dismutase from the Crocodile Icefish Chionodraco hamatus: Antioxidant Defense at Constant Sub-Zero Temperature

Abstract

In the present study, we describe the purification and molecular characterization of Cu,Zn superoxide dismutase (SOD) from Chionodraco hamatus, an Antarctic teleost widely distributed in many areas of the Ross Sea that plays a pivotal role in the Antarctic food chain. The primary sequence was obtained using biochemical and molecular biology approaches and compared with Cu,Zn SODs from other organisms. Multiple sequence alignment using the amino acid sequence revealed that Cu,Zn SOD showed considerable sequence similarity with its orthologues from various vertebrate species, but also some specific substitutions directly linked to cold adaptation. Phylogenetic analyses presented the monophyletic status of Antartic Teleostei among the Perciformes, confirming the erratic differentiation of these proteins and concurring with the theory of the “unclock-like” behavior of Cu,Zn SOD evolution. Expression of C. hamatus Cu,Zn SOD at both the mRNA and protein levels were analyzed in various tissues, highlighting the regulation of gene expression related to environmental stress conditions and also animal physiology. The data presented are the first on the antioxidant enzymes of a fish belonging to the Channichthyidae family and represent an important starting point in understanding the antioxidant systems of these organisms that are subject to constant risk of oxidative stress.

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

“…It is known that mRNAs of stress proteins can be stored in cytoplasmic foci, such as P bodies or stress granules (SG), where they undergo degradation or future translation, respectively [ 55 , 56 ]. This condition is a common trait in organisms adapted to living in stressful environments [ 16 , 57 ], which allows them an extremely rapid response when suddenly exposed to a new stressor. Other studies will be needed to verify if this is the case also in Tetrahymena .…”

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

“…All living organisms respond to a high presence of ROS by increasing the expression of antioxidant enzymes and many other molecules that are elements of the defense and repair toward oxidative damage [10]. Enzymatic antioxidants include proteins such as superoxide dismutase (SOD) [11,12], catalase (CAT) [13], glutathione peroxidase (GPx) [14], peroxiredoxins (Prdx) [15,16], and methionine sulfoxide reductases (Msr) [17]. These enzymes represent a first line against ROS, but do not guarantee complete coverage from the risk of oxidative stress because some compounds, generated by their reactions, are still reactive and potentially cytotoxic, such as the hydrogen peroxide (H 2 O 2 ) produced by SOD.…”

Molecular Characterization, Protein-protein Interaction Network, and Evolution of four Glutathione Peroxidases from <em>Tetrahymena Thermophila</em>

“…It is known that mRNAs of stress proteins can be stored in cytoplasmic foci, such as P bodies or stress granules (SG), where they undergo degradation or future translation, respectively [60,61]. This condition is a common trait in organisms adapted to living in stressful environments [9,19,22], which allows them an extremely rapid response when suddenly exposed to a new stressor. Other studies will be needed to verify if this is the case also in Tetrahymena.…”

“…ROS formation can also be increased as a result of exogenous and endogenous stressors, such as exposure to environmental contaminants, treatment of pathologic conditions with drugs, and onset or progression of diseases [2][3][4][5]. In order to modulate ROS presence, antioxidant molecules are present in cells as a defense against the risk of oxidative stress [6][7][8][9]. Antioxidant enzymes and metabolites should continuously and efficiently work together since small variations in their physiological concentrations can have dramatic effects on the resistance of cellular lipids, proteins, and DNA to oxidative damage.…”

“…Given that some isoforms, such as Tt-gpx11 and Tt-gpx12, represent members of the GPx family in which molecular evolution changed the ancestral structural features, it is possible to hypothesize that positive selection acted only on some portion of the protein. Appropriate analyses on a larger sequence dataset are required to confirm this hypothesis.From the functional point of view, among the proteins that show associations with Tt-GPxs, CAT and peptide-containing tratricopeptide repeat (TRP), responsible for the production and clearance of superoxide[9,47], are in the first cluster. TRP-peptides are often involved in the production of superoxide as a result of an immune response to microbial infection.…”