Oxidative stress protection and the repair response to hydrogen peroxide in the hyperthermophilic archaeon Pyrococcus furiosus and in related species

Abstract

Pyrococcus furiosus is a shallow marine, anaerobic archaeon that grows optimally at 100 degrees C. Addition of H(2)O(2) (0.5 mM) to a growing culture resulted in the cessation of growth with a 2-h 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 H(2)O(2) were not more resistant to the subsequent addition of H(2)O(2) (0.5-5.0 mM). Consequently, there is little if any induced protective response to peroxide. The organism maintains a constitutive protective mechanism involving high levels of oxidoreductase-type enzymes such as superoxide reductase, rubrerythrin, and alkyl hydroperoxide reductase. Related hyperthermophiles contain homologs of the proteins involved in the constitutive protective mechanism but these organisms were more sensitive to peroxide than P. furiosus and lack several of its peroxide-responsive ORFs.

Parallel evolution of transcriptome architecture during genome reorganization

“…These public data sets included 108 Mmp microarrays for a mutant of Ehb membrane-associated hydrogenase (Porat et al 2006), different growth rates, and growth under limiting hydrogen, phosphate, and leucine (Hendrickson et al 2007(Hendrickson et al , 2008; 55 Pfu microarrays for growth under gamma radiation (Williams et al 2007), elemental sulfur (Schut et al 2007), hydrogen peroxide (Strand et al 2010), cold shock , and different carbon sources of peptides and maltose (Schut et al 2003); and 54 Sso microarrays for infection by turreted icosahedral virus (Ortmann et al 2008), growth under different oxygen concentrations (Simon et al 2009), and UV radiation (Gotz et al 2007). The conditional operons were estimated by integrating these public data with those from this study as described in Koide et al (2009).…”

Deletion Strains Reveal Metabolic Roles for Key Elemental Sulfur-Responsive Proteins in Pyrococcus furiosus

“…It includes genes involved in iron-sulfur cluster metabolism (22), as well as the most highly expressed gene in S 0 -grown cells encoding sulfurinduced protein A or SipA (23). SipA expression is regulated in an iron-dependent manner by sulfide, the product of S 0 reduction (4), as well as by oxidative stress (25,26). While the function of SipA is not known, it has been proposed to prevent the precipitation of toxic intracellular insoluble metal sulfides (7) by the controlled reaction of sulfide with assimilated iron and by iron release due to oxidative damage to iron-sulfur clusters (4).…”

Regulation of Iron Metabolism by Pyrococcus furiosus

“…Accordingly, it was shown here that P. furiosus Fur did not bind to the promoter of its own gene in the presence of Fe 2ϩ , Zn 2ϩ , Mn 2ϩ , or Ni 2ϩ ions. Although it cannot be ruled out that Fur has a PerR-like function and plays a role in oxidative stress, expression of fur was not affected by the addition of hydrogen peroxide (29). Fur is poorly conserved not only in the Thermococcaceae but in Euryarchaeota in general, and its function in only a limited number of species is not clear at present.…”

“…Expression of the gene encoding peroxiredoxin (PF1033) decreased by 4.3-fold under iron limitation. Although PF1033 is not predicted to be an ironcontaining protein, the gene encoding it is also upregulated by oxidative stress (hydrogen peroxide) (29). Bacterial peroxiredoxins are peroxidases that catalyze the reduction of hydrogen peroxide, organic hydroperoxides, and peroxynitrite at their cysteinecontaining active sites.…”