Abstract
To avoid molecular damage of biomolecules due to oxidation, all cells have evolved constitutive and responsive systems to mitigate and repair chemical modifications. Archaea have adapted to some of the most extreme environments known to support life, including highly oxidizing conditions. However, in comparison to bacteria and eukaryotes, relatively little is known about the biology and biochemistry of archaea in response to changing conditions and repair of oxidative damage. In this study transcriptome, proteome, and chemical reactivity analyses of hydrogen peroxide (H2O2) induced oxidative stress in Sulfolobus solfataricus (P2) were conducted. Microarray analysis of mRNA expression showed that 102 transcripts were regulated by at least 1.5 fold, 30 minutes after exposure to 30 µM H2O2. Parallel proteomic analyses using two-dimensional differential gel electrophoresis (2D-DIGE), monitored more than 800 proteins 30 and 105 minutes after exposure and found that 18 had significant changes in abundance. A recently characterized ferritin-like antioxidant protein, DPSL, was the most highly regulated species of mRNA and protein, in addition to being post-translationally modified. As expected, a number of antioxidant related mRNAs and proteins were differentially regulated. Three of these, DPSL, superoxide dismutase, and peroxiredoxin were shown to interact and likely form a novel supramolecular complex for mitigating oxidative damage. A scheme for the ability of this complex to perform multi-step reactions is presented. Despite the central role played by DPSL, cells maintained a lower level of protection after disruption of the dpsl gene, indicating a level of redundancy in the oxidative stress pathways of S. solfataricus. This work provides the first “omics” scale assessment of the oxidative stress response for an archeal organism and together with a network analysis using data from previous studies on bacteria and eukaryotes reveals evolutionarily conserved pathways where complex and overlapping defense mechanisms protect against oxygen toxicity.
Highlights
Oxidative stress is a universal phenomenon experienced by both aerobic and anaerobic organisms from all three domains of life [1] and is primarily the result of excess reactive oxygen species (ROS) in the cell
The cells were grown until an OD600 reading of 1 was achieved, at which point oxidative stress was induced by the addition of H2O2 to a final concentration of 30 mM
The transcriptional response was evaluated by microarray at 30 minutes post exposure to 30 mM H2O2 and the proteome was evaluated by 2D-DIGE at both 30 and 105 minutes post exposure to 30 mM H2O2
Summary
Oxidative stress is a universal phenomenon experienced by both aerobic and anaerobic organisms from all three domains of life [1] and is primarily the result of excess reactive oxygen species (ROS) in the cell. Cellular defense mechanisms to counteract oxidation include enzymes and antioxidant molecules (e.g. superoxide dismutases, catalases, peroxidases, thioredoxins, peroxiredoxins and glutathione) [7,8,9,10]. The interplay between these and other cellular components is complex, it has been suggested that a systems biology approach is critical to understanding how the system is orchestrated [11,12,13,14]. Few studies have investigated oxidative stress response in Archaea and an overall comparison between the three domains of life is lacking
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