The Anti-Oxidant Defense System of the Marine Polar Ciliate Euplotes nobilii: Characterization of the MsrB Gene Family

Abstract

Organisms living in polar waters must cope with an extremely stressful environment dominated by freezing temperatures, high oxygen concentrations and UV radiation. To shed light on the genetic mechanisms on which the polar marine ciliate, Euplotes nobilii, relies to effectively cope with the oxidative stress, attention was focused on methionine sulfoxide reductases which repair proteins with oxidized methionines. A family of four structurally distinct MsrB genes, encoding enzymes specific for the reduction of the methionine-sulfoxide R-forms, were identified from a draft of the E. nobilii transcriptionally active (macronuclear) genome. The En-MsrB genes are constitutively expressed to synthesize proteins markedly different in amino acid sequence, number of CXXC motifs for zinc-ion binding, and presence/absence of a cysteine residue specific for the mechanism of enzyme regeneration. The En-MsrB proteins take different localizations in the nucleus, mitochondria, cytosol and endoplasmic reticulum, ensuring a pervasive protection of all the major subcellular compartments from the oxidative damage. These observations have suggested to regard the En-MsrB gene activity as playing a central role in the genetic mechanism that enables E. nobilii and ciliates in general to live in the polar environment.

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

“…Virtually all eukaryotic cells contain Cu,Zn SODs [37][38][39][40][41][42], as well as other anti-stress proteins that allow species to withstand environmental stresses of both natural and anthropogenic origin [43][44][45][46][47][48][49][50][51][52][53]. Our results indicated that a gene coding for cytosolic Cu,Zn SOD is present in the genome of the Antarctic icefish C. hamatus and is expressed as active protein in various organs.…”

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

“…Increased ROS formation 1 , increased DNA damage 9 , antioxidant defense inhibition 10 [196] Homo sapiens PFOA, PFOS Estrogenicity and anti-estrogenicity 12 [202] Homo sapiens PFOA, PFOS, PFNA Estradiol production 13 , progesterone 13 production, testosterone production 13 [203] Homo sapiens PFOA, PFOS Thyroid diseases [213] Homo sapiens PFOA, PFOS Chronic kidney diseases [216] Homo sapiens PFHxS, PFOA, PFOS, PFNA Decreased eGFR 14 [217] Homo sapiens PFHxs, PFOA, PFOS Increased cholesterol outcomes 15 [218] Homo sapiens PFOA, PFOS, PFNA Hyperglycemia 16 , increased serum HDL cholesterol 16 , increased blood insulin 17 [219] Homo sapiens PFOA, PFOS Increased blood levels of glucocorticoid 17 , increased blood levels of androgenic hormones 18 [222]…”

“…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.…”

Heat stress as an innovative approach to enhance the antioxidant production in Pseudooceanicola and Bacillus isolates

“…The production of ROS in plants, algae and microorganisms is induced by a variety of environmental stressors, such as heat, salinity, drought, high light, heavy metals and UV radiation 20,[32][33][34][35][36] . Consequently, plant, protozoa and microbial cells use their antioxidant defense mechanisms to tackle ROS formation threats through enhancing their enzymatic and non-enzymatic antioxidant systems 32,[37][38][39][40] .…”