The hyperthermophilic anaerobe Thermotoga Maritima is able to cope with limited amount of oxygen: insights into its defence strategies

Abstract

Thermotoga maritima, an anaerobic hyperthermophilic bacterium, was found able to grow in the presence of low concentrations of oxygen of up to 0.5% (v/v). Differential proteomics and transcripts analysis by qRT-PCR were used to identify the defence strategies used by T. maritima to protect itself against oxygen. A flavoprotein, homologous to rubredoxin oxygen oxidoreductase was found to be overproduced when cells were cultured in oxidative conditions. The recombinant protein, produced in Escherichia coli, exhibited an oxygen reductase activity, which could account for the observed decrease in oxygen concentration during growth. The gene encoding this oxygen reductase belongs to a multicistronic unit that includes genes encoding proteins involved in exopolysaccharide biosynthesis, which may be related to a biofilm formation induced by the presence of oxygen. Enzymes involved in reactive oxygen species detoxification, iron-sulfur centre synthesis/repair and the cysteine biosynthesis pathway were also overproduced. All these enzymatic systems together contribute to the defence strategy of T. maritima against oxygen. Because of the position of T. maritima in deep branches of the phylogenetic tree, we suggest that these strategies can be considered as ancestral mechanisms first developed by anaerobic microorganisms on the early Earth to protect themselves against primary abiotic or biotic oxygen production.

The Role of PerR in O2-Affected Gene Expression ofClostridium acetobutylicum

“…The production of proteins involved in detoxification and cellular redox balance was most drastically activated, which was expected, as the upregulation of these components was observed recently for a number of bacteria that are considered to be anaerobes (42,47,66 system, which involves FDPs, Dfx, NROR, rubredoxin, and reverse rubrerythrins, emphasized its vital role in survival. Consequently, all of these components were found be the primary targets of PerR repression, as they were overexpressed in the perR-deleted strain and shared a common regulatory motif.…”

“…In a natural environment, exposure to O 2 might occur gradually and, thus, allows an efficient adaptation (31). This has just recently been shown for a number of other bacteria from a diverse group of anaerobes, e.g., Bacteroides fragilis, D. vulgaris, and Thermotoga maritima (3,42,47). The experimental setup presented here was designed so that the level of influx of O 2 was low enough to ensure metabolic activity but sufficient to generate substantial cellular damage.…”

A Detoxifying Oxygen Reductase in the Anaerobic Protozoan Entamoeba histolytica

“…FDPs have been shown to be highly and constitutively expressed both in prokaryotes (in some cases incorporating an oxidative stress response operon [8,18]) and in protozoa (10,25,32). However, an increase in expression upon oxygen exposure has been observed for only one other FDP, that from the hyperthermophilic bacterium Thermotoga maritima, which shows an increase in protein levels with unmatched transcriptional levels and is proposed to sustain the growth of this "strict" anaerobe under microaerophilic conditions (20)(21)(22). The cytoplasmic abundance and increased protein levels in response to oxygen exposure suggest a potential similar function for EhFdp1 in E. histolytica.…”

Oxygen reduction in the strict anaerobe Desulfovibrio vulgaris Hildenborough: characterization of two membrane-bound oxygen reductases

“…Although the function of membranebound terminal oxygen reductases is readily understood in aerobes, the occurrence of such enzymes in strict anaerobes is more intriguing. However, increasing data suggest that many anaerobic micro-organisms, although unable to use oxygen as terminal electron acceptor for growth, have developed defence strategies to protect themselves against oxidative damage and thus exhibit aerotolerance (Cypionka, 2000;Dolla et al, 2006;Kawasaki et al, 2005Kawasaki et al, , 2009Le Fourn et al, 2008). Among these micro-organisms, sulfate-reducing bacteria (SRB) are some of the most studied organisms with regard to aerotolerance mechanisms.…”