Enzymatic Antioxidant Systems in Early Anaerobes: Theoretical Considerations

Abstract

It is widely accepted that cyanobacteria-dependent oxygen that was released into Earth's atmosphere ca. 2.5 billion years ago sparked the evolution of the aerobic metabolism and the antioxidant system. In modern aerobes, enzymes such as superoxide dismutases (SODs), peroxiredoxins (PXs), and catalases (CATs) constitute the core of the enzymatic antioxidant system (EAS) directed against reactive oxygen species (ROS). In many anaerobic prokaryotes, the superoxide reductases (SORs) have been identified as the main force in counteracting ROS toxicity. We found that 93% of the analyzed strict anaerobes possess at least one antioxidant enzyme, and 50% have a functional EAS, that is, consisting of at least two antioxidant enzymes: one for superoxide anion radical detoxification and another for hydrogen peroxide decomposition. The results presented here suggest that the last universal common ancestor (LUCA) was not a strict anaerobe. O 2 could have been available for the first microorganisms before oxygenic photosynthesis evolved, however, from the intrinsic activity of EAS, not solely from abiotic sources.

Methionine Sulfoxide Reductases of Archaea

“…As oxygen levels increased over time, archaea and other microbes were challenged to develop mechanisms to repair and protect against ROS damage. Most archaea today, including strict anaerobes, have at least one antioxidant enzyme to protect and/or repair against ROS damage such as superoxide dismutase, catalase, peroxidiredoxin, superoxide reductase and/or MSR enzymes [ 30 , 31 ] ( Table S1 ). The archaeal MSR enzymes are of particular interest in terms of evolutionary history [ 25 , 28 , 29 ] and how protein homeostasis is maintained in extreme habitats [ 26 ], as these enzymes are recently linked to ubiquitin-like protein modification pathways that are associated with oxidative stress and sulfur mobilization [ 32 ].…”

RETRACTED ARTICLE: The quantum physiology of oxygen; from electrons to the evolution of redox signaling in the human brain

“…•− and H 2 O 2 )/ROS-tolerant organism equipped with a primordial enzymatic antioxidant system that evolved prior to the photosynthetic rise in atmospheric O 2 (Briehl 2015;Slesak et al 2016). Combined with the emerging concept of oxidative hormesis, it is becoming increasingly clear that at physiological concentrations, free radicals and associated ROS have the adaptive capacity to preserve cerebral O 2 homeostasis through cell-cell communication and should not simply be constrained to toxic, mutagenic "accidents" of in-vivo chemistry limited to cellular oxidative damage and pathophysiology (Bailey et al 2018b).…”

RubisCO Early Oxygenase Activity: A Kinetic and Evolutionary Perspective

“…Numbers at nodes represent bootstrap values (based on 500 replications). In order to verify oxygen tolerance, the presence of an enzymatic ROS‐removing system and the occurrence of CO 2 fixation pathways in these organisms the GeneBank ( www.ncbi.nlm.nih.gov/genomes/lproks.cgi), European Bioinformatics Institute ( www.ebi.ac.uk), Doe Joint Genome Institute ( www.jgi.doe.gov) and literature were consulted …”

“…If present‐day obligate anaerobes are descendants of ancient forms, a relatively widespread occurrence of antioxidant enzymes, such as superoxide dismutases (SODs), catalases/peroxidases (CATs/POXs), and peroxiredoxins (PRXs) in many modern strict anaerobes might indicate that rudimentary antioxidant response systems could have appeared as early as ca. 3.0–3.5 Gyr ago, and have been a permanent associate of life (Figure ). In this context, an ancient RubisCO could even be a supplementary component of a rudimentary enzymatic antioxidant system, as suggested previously .…”