Gamma Radiation-induced Proteome of Deinococcus radiodurans Primarily Targets DNA Repair and Oxidative Stress Alleviation

Abstract

The extraordinary radioresistance of Deinococcus radiodurans primarily originates from its efficient DNA repair ability. The kinetics of proteomic changes induced by a 6-kGy dose of gamma irradiation was mapped during the post-irradiation growth arrest phase by two-dimensional protein electrophoresis coupled with mass spectrometry. The results revealed that at least 37 proteins displayed either enhanced or de novo expression in the first 1 h of post-irradiation recovery. All of the radiation-responsive proteins were identified, and they belonged to the major functional categories of DNA repair, oxidative stress alleviation, and protein translation/folding. The dynamics of radiation-responsive protein levels throughout the growth arrest phase demonstrated (i) sequential up-regulation and processing of DNA repair proteins such as singlestranded DNA-binding protein (Ssb), DNA damage response protein A (DdrA), DNA damage response protein B (DdrB), pleiotropic protein promoting DNA repair (PprA), and recombinase A (RecA) substantiating stepwise genome restitution by different DNA repair pathways and (ii) concurrent early up-regulation of proteins involved in both DNA repair and oxidative stress alleviation. Among DNA repair proteins, Ssb was found to be the first and most abundant radiation-induced protein only to be followed by alternate Ssb, DdrB, indicating aggressive protection of single strand DNA fragments as the first line of defense by D. radiodurans, thereby preserving genetic information following radiation stress. The implications of both qualitative or quantitative and sequential or co-induction of radiation-responsive proteins for envisaged DNA repair mechanism in D. radiodurans are discussed.

Interaction of double‐stranded DNA with polymerized PprA protein from Deinococcus radiodurans

“…In addition, it is considered that the large change in molecular weight as PprA concentration increases is important for its function as a pleiotropic protein, because PprA expression is induced following exposure to ionizing radiation. 15,[23][24][25][26][27] It is also considered that the ability of PprA to form higher molecular weight entities is responsible for the extraordinary radioresistance of D. radiodurans. Next, we focused on the DNA-binding characteristics of PprA.…”

“…14,[19][20][21][22] The reported molecular characteristics of PprA are as follows: PprA is induced when the bacterium is exposed to ionizing radiation 15,[23][24][25][26][27] ; PprA can bind to DNA 14,28 31,32 Thus, PprA appears to be a potential pleiotropic protein that functions in the repair of DSBs and other radiation-induced damage. However, the molecular mechanism underlying DNA repair involving PprA remains unclear.…”

Transcriptional Analysis of Deinococcus radiodurans Reveals Novel Small RNAs That Are Differentially Expressed under Ionizing Radiation

“…This phenotype is complex, relying on a set of DNA repair proteins that operate far more efficiently than in naturally radiation-sensitive organisms (32)(33)(34)(35)(36). The molecular basis for the high efficiency of DNA repair proteins in D. radiodurans appears to include the accumulation of manganese antioxidants, which prevent the inactivation of enzymes by reactive oxygen species (ROS) (31,37).…”

“…Various hypotheses have been tested to understand the extreme radioresistance of D. radiodurans (32)(33)(34)(35)(36). This phenotype is complex, relying on a set of DNA repair proteins that operate far more efficiently than in naturally radiation-sensitive organisms (32)(33)(34)(35)(36).…”

Homology Modeling and Comparative Profiling of Superoxide Dismutase Among Extremophiles: Exiguobacterium as a Model Organism

“…Superoxide dismutase (sodA) mutant of D. radiodurans was shown to exhibit a radiosensitive phenotype than the wild type, suggesting the potential role of SODs in regulating radioresistance properties [6]. In a recent study, up-regulated expression of several enzymes related to oxidative stress conditions like catalase (DR1998) and Mn ?2 -dependent superoxide dismutase (DR1279) were observed in the case of D. radiodurans in response to 6 kGy dose of gamma irradiation, which further strengthens their possible role in radiation resistance [7].…”