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Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus.

ABSTRACT: The anaerobic archaeon Pyrococcus furiosus grows by fermenting carbohydrates producing H(2), CO(2), and acetate. We show here that it is surprisingly tolerant to oxygen, growing well in the presence of 8% (vol/vol) O(2). Although cell growth and acetate production were not significantly affected by O(2), H(2) production was reduced by 50% (using 8% O(2)). The amount of H(2) produced decreased in a linear manner with increasing concentrations of O(2) over the range 2-12% (vol/vol), and for each mole of O(2) consumed, the amount of H(2) produced decreased by approximately 2 mol. The recycling of H(2) by the two cytoplasmic hydrogenases appeared not to play a role in O(2) resistance because a mutant strain lacking both enzymes was not more sensitive to O(2) than the parent strain. Decreased H(2) production was also not due to inactivation of the H(2)-producing, ferredoxin-dependent membrane-bound hydrogenase because its activity was unaffected by O(2) exposure. Electrons from carbohydrate oxidation must therefore be diverted to relieve O(2) stress at the level of reduced ferredoxin before H(2) production. Deletion strains lacking superoxide reductase (SOR) and putative flavodiiron protein A showed increased sensitivity to O(2), indicating that these enzymes play primary roles in resisting O(2). However, a mutant strain lacking the proposed electron donor to SOR, rubredoxin, was unaffected in response to O(2). Hence, electrons from sugar oxidation normally used to produce H(2) are diverted to O(2) detoxification by SOR and putative flavodiiron protein A, but the electron flow pathway from ferredoxin does not necessarily involve rubredoxin.|

SUBMITTER: Thorgersen MP

PROVIDER: S-EPMC3494905 | biostudies-other | 2012 Nov

REPOSITORIES: biostudies-other

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Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus.

Thorgersen Michael P MP Stirrett Karen K Scott Robert A RA Adams Michael W W MW Adams Michael W W MW

Proceedings of the National Academy of Sciences of the United States of America 20121023 45

The anaerobic archaeon Pyrococcus furiosus grows by fermenting carbohydrates producing H(2), CO(2), and acetate. We show here that it is surprisingly tolerant to oxygen, growing well in the presence of 8% (vol/vol) O(2). Although cell growth and acetate production were not significantly affected by O(2), H(2) production was reduced by 50% (using 8% O(2)). The amount of H(2) produced decreased in a linear manner with increasing concentrations of O(2) over the range 2-12% (vol/vol), and for each m ...[more]

PMID: 23093671

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Project description:Oxidative Stress Protection and the Repair Response To Hydrogen Peroxide in the Hyperthermophilic Archaeon Pyrococcus furiosus Pyrococcus furiosus is a shallow marine, anaerobic archaeon that grows optimally at 100Â°C. Addition of H2O2 (0.5 mM) to a growing culture resulted in cessation of growth with a 2 hour lag before normal growth resumed. Whole genome transcriptional profiling revealed that the main response occurs within 30 min of peroxide addition, with the up-regulation of 62 open reading frames (ORFs), 36 of which are part of 10 potential operons. More than half of the up-regulated ORFs are of unknown function while some others encode proteins that are involved potentially in sequestering iron and sulfide, in DNA repair and in generating NADPH. This response is thought to involve primarily damage repair rather than protection, since cultures exposed to sub-toxic levels of H2O2 were not more resistant to the subsequent addition of H2O2 (0.5 â 5.0 mM). Consequently, there is little if any induced protective response to peroxide, rather, the organism maintains a constitutive protective mechanism involving high levels of oxidoreductase-type enzymes such as superoxide reductase, rubrerythrin and alkyl hydroperoxide reductase I. The related hyperthermophiles P. woesei and Thermococcus kodakaraensis were more sensitive to peroxide than P. furiosus, apparently due to the lack of several of its peroxide-responsive ORFs. Pyrococcus furiosus (DSM 3638) was grown at 95Â°C in a 20-liter fermentor using maltose as the carbon and energy source. An exponential-phase culture of P. furiosus that had undergone three successive transfers in the experimental medium was used to inoculate the 20-liter fermentor. The culture was shocked with 0.5 mM of hydrogen peroxide (H2O2) when cell density was in mid-exponential phase (~ 5.0 Â´ 107 cells/ml, as determined by direct microscopic cell count). To obtain RNA for microarray and for quantitative PCR (QPCR) analyses, samples (2 liter) were rapidly removed from the fermentor and cooled to 4Â°C. Total RNA was extracted using acid-phenol and stored at -80Â°C until needed. A total of 3 biological replicates in triplicate (3 copies on the same slide) was used in the data set.

Dataset Information

Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus.

Publications

Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus.

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