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Imke Schroder - One of the best experts on this subject based on the ideXlab platform.
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crystal structures of a tetrahedral open pore ferritin from the hyperthermophilic archaeon Archaeoglobus fulgidus
Structure, 2005Co-Authors: Eric E. Johnson, Mari Gingery, Duilio Cascio, Michael R Sawaya, Imke SchroderAbstract:Summary Ferritins are known as important iron storage/detoxification proteins and are widely found in living organisms. This report details the 2.1 A resolution native and 2.7 A resolution iron bound structures of the ferritin from the hyperthermophilic Archaeon Archaeoglobus fulgidus , and represents the first structure of a ferritin from an archaeon, or a hyperthermophilic organism. The A. fulgidus ferritin (AfFtn) monomer has a high degree of structural similarity with archetypal ferritins from E. coli and humans, but the AfFtn quaternary structure is novel; 24 subunits assemble into a shell having tetrahedral (2-3) rather than the canonical octahedral (4-3-2) symmetry of archetypal ferritins. The difference in assembly opens four large (∼45 A) pores in the AfFtn shell. Two nonconservative amino acid substitutions may be critical for stabilizing the tetrahedral form.
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Crystal Structures of a Tetrahedral Open Pore Ferritin from the Hyperthermophilic Archaeon Archaeoglobus fulgidus
Structure (London England : 1993), 2005Co-Authors: Eric E. Johnson, Mari Gingery, Duilio Cascio, Michael R Sawaya, Imke SchroderAbstract:Ferritins are known as important iron storage/detoxification proteins and are widely found in living organisms. This report details the 2.1 A resolution native and 2.7 A resolution iron bound structures of the ferritin from the hyperthermophilic Archaeon Archaeoglobus fulgidus, and represents the first structure of a ferritin from an archaeon, or a hyperthermophilic organism. The A. fulgidus ferritin (AfFtn) monomer has a high degree of structural similarity with archetypal ferritins from E. coli and humans, but the AfFtn quaternary structure is novel; 24 subunits assemble into a shell having tetrahedral (2-3) rather than the canonical octahedral (4-3-2) symmetry of archetypal ferritins. The difference in assembly opens four large (approximately 45 A) pores in the AfFtn shell. Two nonconservative amino acid substitutions may be critical for stabilizing the tetrahedral form.
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A thermostable shikimate 5-dehydrogenase from the archaeon Archaeoglobus fulgidus
FEMS Microbiology Letters, 2004Co-Authors: Sierin Lim, Imke Schroder, Harold G. MonbouquetteAbstract:Shikimate 5-dehydrogenase (SKDH; EC 1.1.1.25) catalyzes the reversible reduction of 3-dehydroshikimate to shikimate and is a key enzyme in the aromatic amino acid biosynthesis pathway. The shikimate 5-dehydrogenase gene, aroE, from Archaeoglobus fulgidus was cloned and overexpressed in Escherichia coli. The recombinant enzyme purified as a homodimer and yielded a maximum specific activity of 732 U/mg at 87 degrees C (with NADP+ as coenzyme). Apparent Km values for shikimate, NADP+, and NAD+ were estimated at 0.17+/-0.03 mM, 0.19+/-0.01 mM, and 11.4+/-0.4 mM, respectively. The half-life of the A. fulgidus SKDH is 2 h at the assay temperature (87 degrees C) and 17 days at 60 degrees C. Addition of 1 M NaCl or KCl stabilized the enzyme's half-life to approximately 70 h at 87 degrees C and approximately 50 days at 60 degrees C. This work presents the first kinetic analysis of an archaeal SKDH.
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Room-temperature synthesis of L-alanine using the alanine dehydrogenase of the hyperthermophilic archaeon Archaeoglobus fulgidus.
Biotechnology progress, 2002Co-Authors: Alexander Vadas, Imke Schroder, Harold G. MonbouquetteAbstract:Alanine dehydrogenase from the hyperthermophilic archaeon Archaeoglobus fulgidus was used at room temperature for batch synthesis of L-alanine by the reductive amination of pyruvate. The reaction mixture included yeast formate dehydrogenase for regeneration of NADH with formate as electron donor. The synthesis of L-alanine at room temperature was accompanied by no detectable loss of alanine dehydrogenase activity over 139 h and > or =99% consumption of pyruvate. The total number of enzyme turnovers was 5.1 million. This work demonstrates the potential utility of novel hyperthermostable enzymes that can be both very active and highly stable at moderate temperature.
Nils-kåre Birkeland - One of the best experts on this subject based on the ideXlab platform.
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The pH optimum of native uracil-DNA glycosylase of Archaeoglobus fulgidus compared to recombinant enzyme indicates adaption to cytosolic pH.
Acta biochimica Polonica, 2014Co-Authors: Ingeborg Knævelsrud, Nils-kåre Birkeland, Sabina Kazazic, Svein BjellandAbstract:Uracil-DNA glycosylase of Archaeoglobus fulgidus (Afung) in cell extracts exhibited maximal activity around pH 6.2 as compared to pH 4.8 for the purified recombinant enzyme expressed in Escherichia coli. Native Afung thus seems to be adapted to the intracellular pH of A. fulgidus, determined to be 7.0±0.1. Both recombinant and native Afung exhibited a broad temperature optimum for activity around 80°C, reflecting the A. fulgidus optimal growth temperature of 83°C. Adaption to the neutral conditions in the A. fulgidus cytoplasm might be due to covalent modifications or accessory factors, or due to a different folding when expressed in the native host.
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The Hyperthermophilic Euryarchaeon Archaeoglobus fulgidus Repairs Uracil by Single-Nucleotide Replacement
Journal of bacteriology, 2010Co-Authors: Ingeborg Knævelsrud, Nils-kåre Birkeland, And Arne Klungland, Marivi N. Moen, Kristin Grøsvik, Gyri Teien Haugland, Ingar Leiros, Svein BjellandAbstract:Hydrolytic deamination of cytosine to uracil in cellular DNA is a major source of C-to-T transition mutations if uracil is not repaired by the DNA base excision repair (BER) pathway. Since deamination increases rapidly with temperature, hyperthermophiles, in particular, are expected to succumb to such damage. There has been only one report of crenarchaeotic BER showing strong similarities to that in most eukaryotes and bacteria for hyperthermophilic Archaea. Here we report a different type of BER performed by extract prepared from cells of the euryarchaeon Archaeoglobus fulgidus. Although immunodepletion showed that the monofunctional family 4 type of uracil-DNA glycosylase (UDG) is the principal and probably only UDG in this organism, a β-elimination mechanism rather than a hydrolytic mechanism is employed for incision of the abasic site following uracil removal. The resulting 3' remnant is removed by efficient 3'-phosphodiesterase activity followed by single-nucleotide insertion and ligation. The finding that repair product formation is stimulated similarly by ATP and ADP in vitro raises the question of whether ADP is more important in vivo because of its higher heat stability.
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Methylpurine DNA glycosylase of the hyperthermophilic archaeon Archaeoglobus fulgidus.
Biochemistry, 2002Co-Authors: Nils-kåre Birkeland, Ingeborg Knævelsrud, Hilde Ånensen, Wenche Kristoffersen, Magnar Bjørås, Frank T. Robb, And Arne Klungland, Svein BjellandAbstract:Base excision repair of DNA alkylation damage is initiated by a methylpurine DNA glycosylase (MPG) function. Such enzymes have previously been characterized from bacteria and eukarya, but not from archaea. We identified activity for the release of methylated bases from DNA in cell-free extracts of Archaeoglobus fulgidus, an archaeon growing optimally at 83 degrees C. An open reading frame homologous to the alkA gene of Escherichia coli was overexpressed and identified as a gene encoding an MPG enzyme (M(r) = 34 251), hereafter designated afalkA. The purified AfalkA protein differs from E. coli AlkA by excising alkylated bases only, from DNA, in the following order of efficiency: 3-methyladenine (m(3)A) >> 3-methylguanine approximately 7-methyladenine >> 7-methylguanine. Although the rate of enzymatic release of m(3)A is highest in the temperature range of 65-75 degrees C, it is only reduced by 50% at 45 degrees C, a temperature that does not support growth of A. fulgidus. At temperatures above 75 degrees C, nonenzymatic release of methylpurines predominates. The results suggest that the biological function of AfalkA is to excise m(3)A from DNA at suboptimal and maybe even mesophilic temperatures. This hypothesis is further supported by the observation that the afalkA gene function suppresses the alkylation sensitivity of the E. coli tag alkA double mutant. The amino acid sequence similarity and evolutionary relationship of AfalkA with other MPG enzymes from the three domains of life are described and discussed.
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chromosome replication patterns in the hyperthermophilic euryarchaea Archaeoglobus fulgidus and methanocaldococcus methanococcus jannaschii
Molecular Microbiology, 2002Co-Authors: Sophie Maisnierpatin, Nils-kåre Birkeland, Laurence Malandrin, Rolf BernanderAbstract:Summary We analysed chromosome replication patterns in the two hyperthermophilic euryarchaea Archaeoglobus fulgidus and Methanocaldococcus (Methanococcus) jannaschii by marker frequency analysis (MFA). For A. fulgidus, the central region of the chromosomal physical map displayed a higher relative abundance in gene dosage during exponential growth, with two continuous gradients to a region of lower abundance at the diametrically opposite side of the genome map. This suggests bidirectional replication of the A. fulgidus chromosome from a single origin. The organization of the putative replication origin region relative to the cdc6, mcm and DNA polymerase genes differed from that reported for Pyrococcus species. No single replication origin or termination regions could be identified for M. jannaschii, adding to the list of unusual properties of this organism. The organization of the A. fulgidus cell cycle was characterized by flow cytometry analysis of the samples from which genomic DNA was extracted for MFA. The relative lengths of the cell cycle periods were found to be similar to those of crenarchaea.
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[2] Isocitrate dehydrogenase, malate dehydrogenase, and glutamate dehydrogenase from Archaeoglobus fulgidus
Methods in enzymology, 2001Co-Authors: Ida Helene Steen, Hilde Hvoslef, Nils-kåre BirkelandAbstract:Publisher Summary Archaeoglobus fulgidus is a hyperthermophilic sulfate-reducing archaeon belonging to the Euryarchaeota . Archaeoglobus fulgidus lacks a complete citric acid cycle, but the presence of enzymes required for the stepwise reductive formation of succinate from oxaloacetate and oxidative formation of 2-oxoglutarate from oxaloacetate and acetyl-CoA has been demonstrated, indicating the involvement of these enzymes in anabolism. Only two of these enzymes, isocitrate dehydrogenase (IDH) and malate dehydrogenase (MDH), have so far been purified and characterized. Glutamate dehydrogenase (GDH), which generally interconnects the citric acid cycle with nitrogen assimilation through a reductive amination of 2-oxogluarate to glutamate, is absent in the A. fulgidus type strain (VC-16), but has been purified from an oil-field isolate (strain 7324), in which it is an abundant protein. This article describes the purification and the catalytic and molecular properties of IDH, GDH, and MDH from A. fulgidus . Their thermostability is also compared. The similarity of the primary structures of IDH and MDH with those of corresponding enzymes from other organisms is discussed.
Hans G. Trüper - One of the best experts on this subject based on the ideXlab platform.
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[33] Sulfite reductase and APS reductase from Archaeoglobus fulgidus
Methods in enzymology, 2001Co-Authors: Christiane Dahl, Hans G. TrüperAbstract:Publisher Summary Archaeoglobus fulgidus carries out sulfate reduction via the pathway originally proposed for bacterial species. All steps of sulfate reduction occur in the cytoplasm, implying that sulfate must be transported across the cytoplasmic membrane. Sulfate transport has not been studied in A. fulgidus , but may resemble that of marine bacterial sulfate reducers, which use sodium ions for the symport of sulfate. The enzyme dissimilatory sulfite reductase catalyzes the six-electron reduction of sulfite to sulfide, which is the central energy-conserving step of sulfate respiration. The natural electron donor of sulfite reductase in sulfate reducers is not known. Thiosulfate reduction in A. fulgidus has not been studied biochemically. Analysis of the A. fulgidus genome sequence revealed the presence of genes encoding several putative molybdopterinbinding oxidoreductases with thiosulfate or polysulfide as potential substrates. This chapter focuses on the purification and characterization of APS reductase and sulfite reductase from A. fulgidus .
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Dissimilatory ATP sulfurylase from Archaeoglobus fulgidus
Methods in enzymology, 2001Co-Authors: Detlef Sperling, Hans G. Trüper, Ulrike Kappler, Christiane DahlAbstract:Publisher Summary The hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus belongs to the kingdom of Euryarchaeota and is grouped with the Methanomicrobiales/extremehalophiles cluster. A. fulgidus has been shown to contain the complete pathway for dissimilatory sulfate reduction known from Bacteria. ATP sulfurylase (MgATP-sulfate adenylyltransferase) is the key enzyme in dissimilatory and assimilatory sulfate reduction. It catalyzes the activation of inorganic sulfate by ATP to give pyrophosphate and adenosine 5'-phosphosulfate (APS), the shared intermediate in these two pathways. In dissimilatory sulfate reduction, APS reductase catalyzes the reduction of APS to AMP and sulfite, which is reduced to sulfide by sulfite reductase. Dissimilatory ATP sulfurylase has also been found in some chemotrophic and phototrophic sulfur-oxidizing bacteria in which it functions in the opposite direction, releasing sulfate and ATP from APS. Dissimilatory ATP sulfurylase have been isolated and characterized from A. fulgidus . The gene encoding this archaeal ATP sulfurylase has been cloned and expressed in Escherichia coli . However, the properties of the recombinant enzyme show significant differences to those of the native enzyme.
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enzymology and molecular biology of sulfate reduction in extremely thermophilic archaeon Archaeoglobus fulgidus
Methods in Enzymology, 1994Co-Authors: Christiane Dahl, Norbert Speich, Hans G. TrüperAbstract:Publisher Summary This chapter describes enzymology and molecular biology of sulfate reduction in Archaeoglobus fulgidus ( A. fulgidus ). A. fulgidus is an extreme thermophile and grows at temperatures between 64 and 92, with an optimum at 83. This organism carries out sulfate reduction via the pathway originally proposed for bacterial species. Owing to its chemical inertia, sulfate needs first to be activated to adenylylsulfate [adenosine-5′-phosphosulfate (APS)] by ATP-sulfurylase [sulfate adenylyltransferase], with formation of pyrophosphate. The enzyme adenylylsulfate (APS) reductase catalyzes the reduction of APS to sulfite and AMP. Sulfite is finally reduced to sulfide by sulfite reductase. Auxiliary enzymes are widely applied in the determination of ATP sulfurylase and sulfite reductase activities from mesophilic organisms. ATP-sulfurylase from A. fulgidus is measured in the thermodynamically favored direction of ATP generation from the reaction of APS with pyrophosphate. The ATP formed is then spectrophotometrically determined. Adenylylsulfate reductase activity is measured in a continuous spectrophotometric assay in the direction of APS formation from sulfite and AMP with ferricyanide as electron acceptor.
Ulrich Ermler - One of the best experts on this subject based on the ideXlab platform.
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conserving energy with sulfate around 100 c structure and mechanism of key metal enzymes in hyperthermophilic Archaeoglobus fulgidus
Metallomics, 2013Co-Authors: Günter Fritz, Ulrich ErmlerAbstract:Sulfate-reducing bacteria and archaea are important players in the biogeochemical sulfur cycle. ATP sulfurylase, adenosine 5′-phosphosulfate reductase and dissimilatory sulfite reductase are the key enzymes in the energy conserving process of SO42− → H2S reduction. This review summarizes recent advances in our understanding of the activation of sulfate to adenosine 5′-phosphosulfate, the following reductive cleavage to SO32− and AMP, and the final six-electron reduction of SO32− to H2S in the hyperthermophilic archaeon Archaeoglobus fulgidus. Structure based mechanisms will be discussed for these three enzymes which host unique metal centers at their catalytic sites.
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Conserving energy with sulfate around 100 °C – structure and mechanism of key metal enzymes in hyperthermophilic Archaeoglobus fulgidus
Metallomics : integrated biometal science, 2013Co-Authors: Günter Fritz, Ulrich ErmlerAbstract:Sulfate-reducing bacteria and archaea are important players in the biogeochemical sulfur cycle. ATP sulfurylase, adenosine 5′-phosphosulfate reductase and dissimilatory sulfite reductase are the key enzymes in the energy conserving process of SO42− → H2S reduction. This review summarizes recent advances in our understanding of the activation of sulfate to adenosine 5′-phosphosulfate, the following reductive cleavage to SO32− and AMP, and the final six-electron reduction of SO32− to H2S in the hyperthermophilic archaeon Archaeoglobus fulgidus. Structure based mechanisms will be discussed for these three enzymes which host unique metal centers at their catalytic sites.
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Reaction cycle of the dissimilatory sulfite reductase from Archaeoglobus fulgidus.
Biochemistry, 2010Co-Authors: Kristian Parey, Eberhard Warkentin, Peter M H Kroneck, Ulrich ErmlerAbstract:A vital process in the biogeochemical sulfur cycle is the dissimilatory sulfate reduction pathway in which sulfate (SO42−) is converted to hydrogen sulfide (H2S). Dissimilatory sulfite reductase (dSir), its key enzyme, hosts a unique siroheme-[4Fe-4S] cofactor and catalyzes the six-electron reduction of sulfite (SO32−) to H2S. To explore this reaction, we determined the X-ray structures of dSir from the archaeon Archaeoglobus fulgidus in complex with sulfite, sulfide (S2−), carbon monoxide (CO), cyanide (CN−), nitrite (NO2−), nitrate (NO3−), and phosphate (PO43−). Activity measurements indicated that dSir of A. fulgidus reduces, besides sulfite and nitrite, thiosulfate (S2O32−) and trithionate (S3O62−) and produces the latter two compounds besides sulfide. On this basis, a three-step mechanism was proposed, each step consisting of a two-electron transfer, a two-proton uptake, and a dehydration event. In comparison, the related active site structures of the assimilatory sulfite reductase (aSir)− and dSir−S...
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Structure of adenylylsulfate reductase from the hyperthermophilic Archaeoglobus fulgidus at 1.6-A resolution.
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Günter Fritz, Harald Huber, Peter M H Kroneck, Karl O Stetter, Annette Roth, Thomas Büchert, Alexander Schiffer, Gleb Bourenkov, Hans D. Bartunik, Ulrich ErmlerAbstract:The iron-sulfur flavoenzyme adenylylsulfate (adenosine 5'-phosphosulfate, APS) reductase catalyzes reversibly the reduction of APS to sulfite and AMP. The structures of APS reductase from the hyperthermophilic Archaeoglobus fulgidus in the two-electron reduced state and with sulfite bound to FAD are reported at 1.6- and 2.5- resolution, respectively. The FAD-sulfite adduct was detected after soaking the crystals with APS. This finding and the architecture of the active site strongly suggest that catalysis involves a nucleophilic attack of the N5 atom of reduced FAD on the sulfur atom of APS. In view of the high degree of similarity between APS reductase and fumarate reductase especially with regard to the FAD-binding alpha-subunit, it is proposed that both subunits originate from a common ancestor resembling archaeal APS reductase. The two electrons required for APS reduction are transferred via two [4Fe-4S] clusters from the surface of the protein to FAD. The exceptionally large difference in reduction potential of these clusters (-60 and -500 mV) can be explained by interactions of the clusters with the protein matrix.
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Crystallization and preliminary X-ray analysis of adenylylsulfate reductase from Archaeoglobus fulgidus.
Acta Crystallographica Section D Biological Crystallography, 2000Co-Authors: Annette Roth, Harald Huber, Karl O Stetter, Günther Fritz, Thomas Büchert, Ulrich ErmlerAbstract:A group of anaerobic microorganisms use sulfate as the terminal electron acceptor for energy conservation. The process of sulfate reduction involves several enzymatic steps. One of them is the conversion of adenylyl sulfate (adenosine-5′-phosphosulfate) to sulfite, catalyzed by adenylylsulfate reductase. This enzyme is composed of a FAD-containing α-subunit and a β-subunit harbouring two [4Fe–4S] clusters. Adenylylsulfate reductase was isolated from Archaeoglobus fulgidus under anaerobic conditions and crystallized using the hanging-drop vapour-diffusion method using PEG 4000 as precipitant. The crystals grew in space group P212121, with unit-cell parameters a = 72.4, b = 113.2, c = 194.0 A. The asymmetric unit probably contains two αβ units. The crystals diffract beyond 2 A resolution and are suitable for X-ray structure analysis.
Harold G. Monbouquette - One of the best experts on this subject based on the ideXlab platform.
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Effect of growth temperature on ether lipid biochemistry in Archaeoglobus fulgidus
Extremophiles : life under extreme conditions, 2007Co-Authors: Denton Lai, James R. Springstead, Harold G. MonbouquetteAbstract:The archaea are distinguished by their unique isoprenoid ether lipids, which typically consist of the sn-2,3-diphytanylglycerol diether or sn-2,3-dibiphytanyldiglycerol tetraether core modified with a variety of polar headgroups. However, many hyperthermophilic archaea also synthesize tetraether lipids with up to four pentacyclic rings per 40-carbon chain, presumably to improve membrane thermal stability at temperatures up to∼110 °C. This study aimed to correlate the ratio of tetraether to diether core lipid, as well as the presence of pentacyclic groups in tetraether lipids, with growth temperature for the hyperthermophilic archaeon, Archaeoglobus fulgidus. Analysis of the membrane core lipids of A. fulgidus using APCI–MS analysis revealed that the tetraether-to-diether lipid ratio increases from 0.3 ± 0.1 for cultures grown at 70°C to 0.9 ± 0.1 for cultures grown at 89°C. Thin-layer chromatography (TLC) followed by APCI–MS analysis provided evidence for no more than one pentacycle in the hydrocarbon chains of tetraether lipid from cultures grown at 70°C and up to 2 pentacycles in the tetraether lipid from cultures grown at higher temperatures. Analysis of the polar lipid extract using TLC and negative-ion ESI–MS suggested the presence of diether and tetraether phospholipids with inositol, glycosyl, and ethanolamine headgroup chemistry.
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A thermostable shikimate 5-dehydrogenase from the archaeon Archaeoglobus fulgidus
FEMS Microbiology Letters, 2004Co-Authors: Sierin Lim, Imke Schroder, Harold G. MonbouquetteAbstract:Shikimate 5-dehydrogenase (SKDH; EC 1.1.1.25) catalyzes the reversible reduction of 3-dehydroshikimate to shikimate and is a key enzyme in the aromatic amino acid biosynthesis pathway. The shikimate 5-dehydrogenase gene, aroE, from Archaeoglobus fulgidus was cloned and overexpressed in Escherichia coli. The recombinant enzyme purified as a homodimer and yielded a maximum specific activity of 732 U/mg at 87 degrees C (with NADP+ as coenzyme). Apparent Km values for shikimate, NADP+, and NAD+ were estimated at 0.17+/-0.03 mM, 0.19+/-0.01 mM, and 11.4+/-0.4 mM, respectively. The half-life of the A. fulgidus SKDH is 2 h at the assay temperature (87 degrees C) and 17 days at 60 degrees C. Addition of 1 M NaCl or KCl stabilized the enzyme's half-life to approximately 70 h at 87 degrees C and approximately 50 days at 60 degrees C. This work presents the first kinetic analysis of an archaeal SKDH.
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Room-temperature synthesis of L-alanine using the alanine dehydrogenase of the hyperthermophilic archaeon Archaeoglobus fulgidus.
Biotechnology progress, 2002Co-Authors: Alexander Vadas, Imke Schroder, Harold G. MonbouquetteAbstract:Alanine dehydrogenase from the hyperthermophilic archaeon Archaeoglobus fulgidus was used at room temperature for batch synthesis of L-alanine by the reductive amination of pyruvate. The reaction mixture included yeast formate dehydrogenase for regeneration of NADH with formate as electron donor. The synthesis of L-alanine at room temperature was accompanied by no detectable loss of alanine dehydrogenase activity over 139 h and > or =99% consumption of pyruvate. The total number of enzyme turnovers was 5.1 million. This work demonstrates the potential utility of novel hyperthermostable enzymes that can be both very active and highly stable at moderate temperature.
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Purification and characterization of Archaeoglobus fulgidus shikimate 5-dehydrogenase
Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and, 1Co-Authors: Sierin Lim, Chihee Kim, I. Schroder, Harold G. MonbouquetteAbstract:Shikimate 5-dehydrogenase (EC 1.1.1.25) is an important enzyme of the aromatic amino acid biosynthesis pathway. The shikimate 5-dehydrogenase (SDH) gene from the hyperthermophile Archaeoglobus fulgidus was PCR cloned and over-expressed in E. coli. The resulting recombinant enzyme with a M/sub r/ of 27,000 was purified to homogeneity. The enzyme had a specific activity of 727 U/mg at 87/spl deg/C, and exhibited K/sub m/s for shikimate and NADP/sup +/ of 0.17 /spl plusmn/ 0.03 mM and 0.19 /spl plusmn/ 0.01, respectively. At 87/spl deg/C, the half life of the SDH was 2 hours. At 60/spl deg/C and a specific activity of 104 U/mg, the half life was 17 days. The combination of high stability and activity for this archaeal SDH may make it useful for industrial chiral synthesis.