Unique sugar metabolism and novel enzymes of hyperthermophilic archaea

Sakuraba, Haruhiko; Goda, Shuichiro; Ohshima, Toshihisa

doi:10.1002/tcr.10066

Cited by 44 publications

(25 citation statements)

References 40 publications

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“…7), suggesting that this E1p ␣-subunit gene has been recruited via gene transfer from the gram-positive bacteria. The obvious absence of PDHCs in other archaea (70) is in agreement with the finding that the oxidative decarboxylation of pyruvate is generally catalyzed by pyruvate:ferredoxin oxidoreductases in archaea (31,32,47).…”

Section: Discussionsupporting

confidence: 89%

E1 Enzyme of the Pyruvate Dehydrogenase Complex in Corynebacterium glutamicum : Molecular Analysis of the Gene and Phylogenetic Aspects

et al. 2005

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The E1p enzyme is an essential part of the pyruvate dehydrogenase complex (PDHC) and catalyzes the oxidative decarboxylation of pyruvate with concomitant acetylation of the E2p enzyme within the complex. We analyzed the Corynebacterium glutamicum aceE gene, encoding the E1p enzyme, and constructed and characterized an E1p-deficient mutant. Sequence analysis of the C. glutamicum aceE gene and adjacent regions revealed that aceE is not flanked by genes encoding other enzymes of the PDHC. Transcriptional analysis revealed that aceE from C. glutamicum is monocistronic and that its transcription is initiated 121 nucleotides upstream of the translational start site. Inactivation of the chromosomal aceE gene led to the inability to grow on glucose and to the absence of PDHC and E1p activities, indicating that only a single E1p enzyme is present in C. glutamicum and that the PDHC is essential for the growth of this organism on carbohydrate substrates. Surprisingly, the E1p enzyme of C. glutamicum showed up to 51% identity to homodimeric E1p proteins from gram-negative bacteria but no similarity to E1 ␣-or ␤-subunits of heterotetrameric E1p enzymes which are generally assumed to be typical for gram-positives. To investigate the distribution of E1p enzymes in bacteria, we compiled and analyzed the phylogeny of 46 homodimeric E1p proteins and of 58 ␣-subunits of heterotetrameric E1p proteins deposited in public databases. The results revealed that the distribution of homodimeric and heterotetrameric E1p subunits in bacteria is not in accordance with the rRNA-based phylogeny of bacteria and is more heterogeneous than previously assumed.The pyruvate dehydrogenase complex (PDHC) represents a member of a multienzyme complex family that also comprises the 2-oxoglutarate dehydrogenase complex (OGDHC) and the branched-chain 2-oxoacid dehydrogenase complex (BCOADHC). These enzymes catalyze the oxidative decarboxylation of pyruvate, 2-oxoglutarate, and the 2-oxo acids of the branched-chain amino acids L-leucine, L-valine, and L-isoleucine, respectively. In general, the multienzyme complexes are composed of multiple copies of three different enzymes, a thiamine pyrophosphate (TPP) containing 2-oxoacid decarboxylase (E1), a lipoic acid-containing dihydrolipoamide acyltransferase (E2), and the flavin-containing lipoamide dehydrogenase (LPD). The E1 enzyme catalyzes the irreversible, TPP-dependent oxidative decarboxylation of the 2-oxoacid, followed by the acylation of the lipoyl prosthetic group covalently attached to the E2 chain. The E2 component catalyzes the transfer of the acyl group from the lipoyl group to coenzyme A (CoA). The resulting dihydrolipoyl group is reoxidized by LPD, generating NADH and H ϩ from NAD ϩ (for a recent review, see reference 11). The E1 and E2 enzymes are specific for each of the three multienzyme complexes and therefore specified as E1p and E2p in the PDHC, E1o and E2o in the OGDHC, and E1b, and E2b in the BCOADHC. In contrast, the LPD component is common in the three multienzyme complexes in most organ...

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Section: Discussionsupporting

confidence: 89%

E1 Enzyme of the Pyruvate Dehydrogenase Complex in Corynebacterium glutamicum : Molecular Analysis of the Gene and Phylogenetic Aspects

et al. 2005

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“…Whereas the pyruvate kinase reaction is considered to be irreversible (PEP ϩ ADP ↔ pyruvate ϩ ATP; ⌬G ϭ Ϫ25.5 kJ mol Ϫ1 ), the Gibbs free energy of the PEPS reaction is close to zero (PEP ϩ AMP ϩ P i ↔ pyruvate ϩ ATP ϩ H 2 O; ⌬G ϭ 0.17 kJ mol Ϫ1 ), and a glycolytic function of PEPS has been suggested (37,322,323,468). The enzymatic characterization of PEPS from Pyr.…”

Section: Thermococcales (Pyrococcus Furiosus and Thermococcus Kodakarmentioning

confidence: 99%

Carbohydrate Metabolism in Archaea: Current Insights into Unusual Enzymes and Pathways and Their Regulation

Bräsen

Esser

Rauch

et al. 2014

Microbiol Mol Biol Rev

280

294

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SUMMARY The metabolism of Archaea , the third domain of life, resembles in its complexity those of Bacteria and lower Eukarya . However, this metabolic complexity in Archaea is accompanied by the absence of many “classical” pathways, particularly in central carbohydrate metabolism. Instead, Archaea are characterized by the presence of unique, modified variants of classical pathways such as the Embden-Meyerhof-Parnas (EMP) pathway and the Entner-Doudoroff (ED) pathway. The pentose phosphate pathway is only partly present (if at all), and pentose degradation also significantly differs from that known for bacterial model organisms. These modifications are accompanied by the invention of “new,” unusual enzymes which cause fundamental consequences for the underlying regulatory principles, and classical allosteric regulation sites well established in Bacteria and Eukarya are lost. The aim of this review is to present the current understanding of central carbohydrate metabolic pathways and their regulation in Archaea . In order to give an overview of their complexity, pathway modifications are discussed with respect to unusual archaeal biocatalysts, their structural and mechanistic characteristics, and their regulatory properties in comparison to their classic counterparts from Bacteria and Eukarya . Furthermore, an overview focusing on hexose metabolic, i.e., glycolytic as well as gluconeogenic, pathways identified in archaeal model organisms is given. Their energy gain is discussed, and new insights into different levels of regulation that have been observed so far, including the transcript and protein levels (e.g., gene regulation, known transcription regulators, and posttranslational modification via reversible protein phosphorylation), are presented.

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“…Although much has been reported about the role of specific enzymes and proteins in the central metabolic pathways of P. furiosus (17,44,45), the mechanism of S 0 reduction and the impact of S 0 on this archaeon's bioenergetics are still not clear. Sulfur reduction proceeds through polysulfides produced by nucleophilic attack on elemental sulfur (6), but so far the mechanism of S 0 reduction has been studied only in maltosegrown cells.…”

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confidence: 99%

Impact of Substrate Glycoside Linkage and Elemental Sulfur on Bioenergetics of and Hydrogen Production by the Hyperthermophilic Archaeon Pyrococcus furiosus

Chou

Shockley

Conners

et al. 2007

Appl Environ Microbiol

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Glycoside linkage (cellobiose versus maltose) dramatically influenced bioenergetics to different extents and by different mechanisms in the hyperthermophilic archaeon Pyrococcus furiosus when it was grown in continuous culture at a dilution rate of 0.45 h ؊1 at 90°C. In the absence of S 0 , cellobiose-grown cells generated twice as much protein and had 50%-higher specific H 2 generation rates than maltose-grown cultures. Addition of S 0 to maltose-grown cultures boosted cell protein production fourfold and shifted gas production completely from H 2 to H 2 S. In contrast, the presence of S 0 in cellobiose-grown cells caused only a 1.3-fold increase in protein production and an incomplete shift from H 2 to H 2 S production, with 2.5 times more H 2 than H 2 S formed. Transcriptional response analysis revealed that many genes and operons known to be involved in ␣-or ␤-glucan uptake and processing were up-regulated in an S 0 -independent manner. Most differentially transcribed open reading frames (ORFs) responding to S 0 in cellobiose-grown cells also responded to S 0 in maltose-grown cells; these ORFs included ORFs encoding a membrane-bound oxidoreductase complex (MBX) and two hypothetical proteins (PF2025 and PF2026). However, additional genes (242 genes; 108 genes were up-regulated and 134 genes were down-regulated) were differentially transcribed when S 0 was present in the medium of maltose-grown cells, indicating that there were different cellular responses to the two sugars. These results indicate that carbohydrate characteristics (e.g., glycoside linkage) have a major impact on S 0 metabolism and hydrogen production in P. furiosus. Furthermore, such issues need to be considered in designing and implementing metabolic strategies for production of biofuel by fermentative anaerobes.Because of problems with sufficient access to petroleum and natural gas resources and the emerging threat of global warming, there is increasing interest in alternative energy options to supplement or replace fossil fuels (43). One prospect that has received considerable attention is the conversion of renewable resources (i.e., biomass) to ethanol using biological routes (20). While availability of bioprocess-based ethanol could offset current demands to some extent, problems with significant CO 2 emissions upon energy conversion would remain (37). A longer-term option being considered is the production of molecular hydrogen from biomass using fermentative, anaerobic microorganisms (38). For example, many mesophilic Clostridium and Enterobacter species can grow on fermentable sugars and produce hydrogen as a by-product of energy metabolism (8,11,16,28,38).Studies suggest that biohydrogen production rates may be enhanced at higher temperatures (9, 23). In fact, the production and consumption of molecular hydrogen drive the microbial physiology and bioenergetics of many hyperthermophilic bacteria and archaea inhabiting hydrothermal environments (1). The potential of these microorganisms for biofuel processes has not gone unnoticed (25)....

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Unique sugar metabolism and novel enzymes of hyperthermophilic archaea

Cited by 44 publications

References 40 publications

E1 Enzyme of the Pyruvate Dehydrogenase Complex in Corynebacterium glutamicum : Molecular Analysis of the Gene and Phylogenetic Aspects

E1 Enzyme of the Pyruvate Dehydrogenase Complex in Corynebacterium glutamicum : Molecular Analysis of the Gene and Phylogenetic Aspects

Carbohydrate Metabolism in Archaea: Current Insights into Unusual Enzymes and Pathways and Their Regulation

Impact of Substrate Glycoside Linkage and Elemental Sulfur on Bioenergetics of and Hydrogen Production by the Hyperthermophilic Archaeon Pyrococcus furiosus

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