The Elemental Sulfur-Responsive Protein (SipA) from the Hyperthermophilic Archaeon
            <i>Pyrococcus furiosus</i>
            Is Regulated by Sulfide in an Iron-Dependent Manner

Clarkson, Sonya M.; Newcomer, Elizabeth C.; Young, Everett; Adams, Michael W. W.

doi:10.1128/jb.00660-10

Cited by 8 publications

(17 citation statements)

References 16 publications

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“…Glycolysis generates reduced ferredoxins (Fd red ) that must be re‐oxidized (Fd ox ) to maintain metabolic flow and conserve energy for growth. Based on analyses of culture products (Kanai et al ., 2005), the activities of enzymes and complexes purified from T. kodakarensis and closely related Thermococcales (Ma et al ., 2000; Sapra et al ., 2000; 2003; Ma and Adams, 2001a; Lee et al ., 2006; Chou et al ., 2007; Schut et al ., 2007; Lipscomb et al ., 2009; 2011; Clarkson et al ., 2010; Kobori et al ., 2010; Yang et al ., 2010), and the genome annotation (Fukui et al ., 2005), T. kodakarensis has several different systems to accomplish the regeneration of Fd ox from Fd red . Most of these predicted electron disposal pathways use sulfur (S°) as the terminal electron acceptor, generating H 2 S, but there are also pathways that result in alanine or H 2 production (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…TS1102 (ΔTK1260‐1261). Microarray hybridizations revealed that S° addition to P. furiosus cultures dramatically increased the transcription of two genes, designated sipA and sipB (S°‐induced proteins A and B), predicted to encode a nucleotide pyrophosphohydrolase and transcription regulator (Chou et al ., 2007; Clarkson et al ., 2010). The homologous genes in T. kodakarensis (TK1260 and TK1261) appear to form an operon that was deleted in T. kodakarensis TS1102.…”

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confidence: 99%

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Deletion of alternative pathways for reductant recycling in Thermococcus kodakarensis increases hydrogen production

Santangelo

Čuboňová

Reeve

2011

Molecular Microbiology

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Summary Hydrogen (H2) production by Thermococcus kodakarensis compares very favorably with the levels reported for the most productive algal, fungal and bacterial systems. T. kodakarensis can also consume H2 and is predicted to use several alternative pathways to recycle reduced cofactors, some of which may compete with H2 production for reductant disposal. To explore the reductant flux and possible competition for H2 production in vivo, T. kodakarensis TS517 was mutated to precisely delete each of the alternative pathways of reductant disposal, H2 production and consumption. The results obtained establish that H2 is generated predominantly by the membrane-bound hydrogenase complex (Mbh), confirm the essential role of the SurR (TK1086p) regulator in vivo, delineate the roles of sulfur (S°) regulon proteins and demonstrate that preventing H2 consumption results in a substantial net increase in H2 production. Constitutive expression of TK1086 (surR) from a replicative plasmid restored the ability of T. kodakarensis TS1101 (ΔTK1086) to grow in the absence of S° and stimulated H2 production, revealing a second mechanism to increase H2 production. Transformation of T. kodakarensis TS1101 with plasmids that express SurR variants constructed to direct the constitutive synthesis of the Mbh complex and prevent expression of the S°-regulon was only possible in the absence of S° and, under these conditions, the transformants exhibited wild-type growth and H2 production. With S° present, they grew slower but synthesized more H2 per unit biomass than T. kodakarensis TS517.

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Deletion of alternative pathways for reductant recycling in Thermococcus kodakarensis increases hydrogen production

Santangelo

Čuboňová

Reeve

2011

Molecular Microbiology

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“…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).…”

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confidence: 99%

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

et al. 2011

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Transcriptional and enzymatic analyses of Pyrococcus furiosus previously indicated that three proteins play key roles in the metabolism of elemental sulfur (S 0 ): a membrane-bound oxidoreductase complex (MBX), a cytoplasmic coenzyme A-dependent NADPH sulfur oxidoreductase (NSR), and sulfur-induced protein A (SipA). Deletion strains, referred to as MBX1, NSR1, and SIP1, respectively, have now been constructed by homologous recombination utilizing the uracil auxotrophic COM1 parent strain (⌬pyrF). The growth of all three mutants on maltose was comparable without S 0 , but in its presence, the growth of MBX1 was greatly impaired while the growth of NSR1 and SIP1 was largely unaffected. In the presence of S 0 , MBX1 produced little, if any, sulfide but much more acetate (per unit of protein) than the parent strain, demonstrating that MBX plays a critical role in S 0 reduction and energy conservation. In contrast, comparable amounts of sulfide and acetate were produced by NSR1 and the parent strain, indicating that NSR is not essential for energy conservation during S 0 reduction. Differences in transcriptional responses to S 0 in NSR1 suggest that two sulfide dehydrogenase isoenzymes provide a compensatory NADPH-dependent S 0 reduction system. Genes controlled by the S 0 -responsive regulator SurR were not as highly regulated in MBX1 and NSR1. SIP1 produced the same amount of acetate but more sulfide than the parent strain. That SipA is not essential for growth on S 0 indicates that it is not required for detoxification of metal sulfides, as previously suggested. A model is proposed for S 0 reduction by P. furiosus with roles for MBX and NSR in bioenergetics and for SipA in iron-sulfur metabolism.

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“…The upregulation of expression of the suf operon in P. furiosus is a secondary response to elemental sulfur, presumably due to a decrease in the intracellular iron concentration during sulfur reduction (31). Interestingly, a recent study of an ironsulfur detoxification protein termed SipA in P. furiosus showed that transcription of its gene is regulated by sulfide in an irondependent manner (12). Our EMSA results for DtxR with the putative sipA promoter showed that a specific binding complex was formed (data not shown), indicating that DtxR is possibly involved in the regulation of sipA in response to iron.…”

Section: Discussionmentioning

confidence: 99%

“…These include three hydrogenases (MBH, SHI, and SHII) (4,5), which are involved in hydrogen metabolism, superoxide reductase (SOR) and rubrerythrin, which are involved in the response to oxidative stress (6,7), and the primary redox proteins, ferredoxin and rubredoxin, both of which contain iron (8,9). Furthermore, ferritin and Dps of P. furiosus have been shown to be potential iron storage proteins, and the elemental-sulfur-induced protein A (SipA) was found to sequester intracellular iron and sulfide when iron and sulfur were present in the growth medium (10)(11)(12). Given the abundance of iron-containing proteins in this organism, the goal of the present study was to understand its response to iron availability.…”

Section: T He Hyperthermophilic Anaerobic Archaeon Pyrococcus Furiosusmentioning

confidence: 99%

Regulation of Iron Metabolism by Pyrococcus furiosus

et al. 2013

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Iron is an essential element for the hyperthermophilic archaeon Pyrococcus furiosus, and many of its iron-containing enzymes have been characterized. How iron assimilation is regulated, however, is unknown. The genome sequence contains genes encoding two putative iron-responsive transcription factors, DtxR and Fur. Global transcriptional profiles of the dtxR deletion mutant (⌬DTXR) and the parent strain under iron-sufficient and iron-limited conditions indicated that DtxR represses the expression of the genes encoding two putative iron transporters, Ftr1 and FeoAB, under iron-sufficient conditions. Under iron limitation, DtxR represses expression of the gene encoding the iron-containing enzyme aldehyde ferredoxin oxidoreductase and a putative ABC-type transporter. Analysis of the dtxR gene sequence indicated an incorrectly predicted translation start site, and the corrected full-length DtxR protein, in contrast to the truncated version, specifically bound to the promoters of ftr1 and feoAB, confirming its role as a transcription regulator. Expression of the gene encoding Ftr1 was dramatically upregulated by iron limitation, but no phenotype was observed for the ⌬FTR1 deletion mutant under iron-limited conditions. The intracellular iron concentrations of ⌬FTR1 and the parent strain were similar, suggesting that under the conditions tested, Ftr1 is not an essential iron transporter despite its response to iron. In contrast to DtxR, the Fur protein appears not to be a functional regulator in P. furiosus, since it did not bind to the promoters of any of the iron-regulated genes and the deletion mutant (⌬FUR) revealed no transcriptional responses to iron availability. DtxR is therefore the key iron-responsive transcriptional regulator in P. furiosus. T he hyperthermophilic anaerobic archaeon Pyrococcus furiosushas an optimal growth temperature of 100°C (1). It is of biotechnological interest as a source of highly thermostable enzymes and because of its ability to produce hydrogen gas (2, 3). It is well established that the organism requires iron for efficient growth, and a number of iron-containing enzymes involved in the primary metabolic pathways of P. furiosus have been characterized. These include three hydrogenases (MBH, SHI, and SHII) (4, 5), which are involved in hydrogen metabolism, superoxide reductase (SOR) and rubrerythrin, which are involved in the response to oxidative stress (6, 7), and the primary redox proteins, ferredoxin and rubredoxin, both of which contain iron (8, 9). Furthermore, ferritin and Dps of P. furiosus have been shown to be potential iron storage proteins, and the elemental-sulfur-induced protein A (SipA) was found to sequester intracellular iron and sulfide when iron and sulfur were present in the growth medium (10-12). Given the abundance of iron-containing proteins in this organism, the goal of the present study was to understand its response to iron availability.Iron metabolism is usually tightly regulated in aerobic organisms at the transcriptional level due to potential oxidative ...

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The Elemental Sulfur-Responsive Protein (SipA) from the Hyperthermophilic Archaeon Pyrococcus furiosus Is Regulated by Sulfide in an Iron-Dependent Manner

Cited by 8 publications

References 16 publications

Deletion of alternative pathways for reductant recycling in Thermococcus kodakarensis increases hydrogen production

Deletion of alternative pathways for reductant recycling in Thermococcus kodakarensis increases hydrogen production

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

Regulation of Iron Metabolism by Pyrococcus furiosus

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