Oxygen and Hydrogen Peroxide in the Early Evolution of Life on Earth:In silicoComparative Analysis of Biochemical Pathways

Abstract

In the Universe, oxygen is the third most widespread element, while on Earth it is the most abundant one. Moreover, oxygen is a major constituent of all biopolymers fundamental to living organisms. Besides O 2 , reactive oxygen species (ROS), among them hydrogen peroxide (H 2 O 2 ), are also important reactants in the present aerobic metabolism. According to a widely accepted hypothesis, aerobic metabolism and many other reactions/pathways involving O 2 appeared after the evolution of oxygenic photosynthesis. In this study, the hypothesis was formulated that the Last Universal Common Ancestor (LUCA) was at least able to tolerate O 2 and detoxify ROS in a primordial environment. A comparative analysis was carried out of a number of the O 2 -and H 2 O 2 -involving metabolic reactions that occur in strict anaerobes, facultative anaerobes, and aerobes. The results indicate that the most likely LUCA possessed O 2 -and H 2 O 2 -involving pathways, mainly reactions to remove ROS, and had, at least in part, the components of aerobic respiration. Based on this, the presence of a low, but significant, quantity of H 2 O 2 and O 2 should be taken into account in theoretical models of the early Archean atmosphere and oceans and the evolution of life. It is suggested that the early metabolism involving O 2 /H 2 O 2 was a key adaptation of LUCA to already existing weakly oxic zones in Earth's primordial environment.

Hydrogen Peroxide Cycling in High-Temperature Acidic Geothermal Springs and Potential Implications for Oxidative Stress Response

“…Hydrogen peroxide (H 2 O 2 ) is a central reactive oxygen species (ROS) in the global cycle of oxygen (O 2 ), and is thought to have been a precursor to O 2 via abiotic reactions in early Earth (Slesak et al, 2012). ROS such as H 2 O 2 and superoxide (O…”

Enzymatic Antioxidant Systems in Early Anaerobes: Theoretical Considerations

“…In fact, in modern anaerobes, components of aerobic respiration, and EAS, such as various cytochrome oxidases (Baughn and Malamy, 2004;Das et al, 2005;Dolla et al, 2006), NADH oxidases (Yang and Ma, 2007), SODs (Gregory et al, 1978;Dos Santos et al, 2000;Brioukhanov and Netrusov, 2004;Dolla et al, 2006;Horne and Lessner, 2013), SORs (Niviére and Fontecave, 2004;Dolla et al, 2006), and CATs (Brioukhanov and Netrusov, 2004;Dolla et al, 2006;Mishra and Imlay, 2013) have been identified previously. According to other reports, enzymes and metabolic pathways that are directly or indirectly oxygendependent are present in many anaerobes (Peregrin-Alvarez et al, 2003;Freitas et al, 2005;Raymond and Segrè, 2006;Passardi et al, 2007;Ś lesak et al, 2012). Moreover, according to theoretical studies, Fe/MnSOD and CAT would have been required for basic metabolism of the hypothetical LUCA (Ouzounis et al, 2006).…”

Are We Alone? The Search for Life on Mars and Other Planetary Bodies

“…Data collected during the Viking missions showed that the surface of Mars was highly oxidized compared to the Mars atmosphere [13]. Mapping of hydrogen peroxide (H 2 O 2 ) on Mars using infrared high-resolution imaging spectroscopy indicated H 2 O 2 abundance on Mars is 15 ± 10 ppb although prior mapping showed concentrations as high as 40 ppb [14].…”

“…Data from the Viking missions showed that the surface of Mars was highly oxidized compared to its atmosphere [13]. Additional studies of Mars have shown that H 2 O 2 abundance can range from 15 ± 10 ppb to 40 ppb [14].…”