Enzymes of gluconeogenesis in the autotroph Methanobacterium thermoautotrophicum

Fuchs, Georg; Winter, Heike; Steiner, Iris; Stupperich, Erhard

doi:10.1007/bf00404793

Cited by 44 publications

(29 citation statements)

References 9 publications

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“…Labeling experiments with 14 CO 2 in Mba. thermautotrophicus in conjunction with enzyme measurements confirmed the presence of gluconeogenesis via the EMP pathway (PEPS, the only anabolic aldolase) (315,333).…”

Section: Fig 28mentioning

confidence: 92%

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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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Section: Fig 28mentioning

confidence: 92%

“…However, FBPase activity was demonstrated in Archaea growing under gluconeogenic conditions (198,333). In Mca.…”

Section: Bifunctional Fructose-16-bisphosphate Aldolase/phosphatasementioning

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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“…However, an examination of the properties of class I eubacterial aldolases, shows that, other than the NaBH, test, they do not necessarily share other characteristics of eukaryotic aldolases. The presence of aldola se activity has been reported in other archaebacteria but hardly any details are available [35]. The aldolase activity in the archaebacterium Methanobacterium thermoautotrophicum, because of lack of EDTA inhibition, was considered to be class I type, though it is not clear how the requirement of a high concentration of Mg2+ (20 mM) for activity can be reconciled with such a classification [35].…”

Section: Discussionmentioning

confidence: 99%

An unusual class I (Schiff base) fructose‐1,6‐bisphosphate aldolase from the halophilic archaebacterium Haloarcula vallismortis

Krishnan

Altekar

1991

European Journal of Biochemistry

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An electrophoretically homogeneous class I (Schiff base) alsolase has been isolated for the first time from the archaebacterial halophile Haloarcula (Halobacterium) vallismortis. The aldolase was characterized with respect to its molecular mass, amino acid composition, salt dependency, immunological cross-reactivity and kinetic properties. The subunit mass of aldolase is 27 kDa, which is much smaller than other class I aldolases. By the gel filtration method, the molecular mass of the halobacterial enzyme was estimated as 280 k 10 kDa, suggesting a decameric nature. In contrast to many halobacterial proteins, the H . vallismortis aldolase, though a halophilic enzyme, did not show an excess of acidic residues. Unlike the eukaryotic aldolases, the activity of the halobacterial enzyme was not affected by carboxypeptidase digestion. The general catalytic features of the enzyme were similar to its counterparts from other sources. No antigenic similarity could be detected between the H. vallisrnortis aldolase and class I aldolase from eubacteria and eukaryotes or class I1 halobacterial aldolases.Two types of fructose-l,6-bisphosphate [Fru(l,6)Pz] aldolases, viz. class I and class 11, are known. Aldolases from most microorganisms show the characteristics of class 11 and are metalloenzymes [l]. Thus, class I1 aldolases are inhibited by EDTA as they are dependent on a divalent metal ion for the stabilization of the carbanion intermediate of the aldolasesubstrate complex [l]. In contrast, the class I aldolases distributed in higher forms of life, such as animals, protozoa, algae and higher plants, form a Schiff base intermediate involving the e-NH, group of a lysine residue and glycerone phosphate (GrnP) [2]. This Schiff base can be reduced with NaBH4, thereby inactivating the enzyme irreversibly [2].From the information then available on the restrictive phylogenetic segregation of aldolases in nature, it was considered that the gene for class I aldolase appeared later than that for the class I1 enzyme [l]. Therefore the identification of class I aldolases in certain eubacteria came as a surprise. These bacteria were : Micrococcus aerogenes [3,4], Lactobacillus casei [5, 61, Mycobacterium smegmatis [7], Escherichia coli [8], Staphylococcus aureus [9] and species of Staphylococci and Peptococci [lo]. The amino acid sequences near the active site reported for M . aerogenes [4] and S. aureus [ll] were shown to exhibit 48% and 21 YO similarity, respectively, with the mammalian aldolases. Recently our work on halobacterial aldolases has added the name of archaebacterial halophiles to this list of unusual class I aldolases in prokaryotes [12, 131.

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“…Although Class I and Class II FBP aldolase activities have been demonstrated in Archaea (15)(16)(17)(18)(19)(20)(21), no genes encoding classical Class I or II enzymes have been identified in any of the sequenced archaeal genomes suggesting that Archaea possess novel types of aldolases that are either absent or not yet recognized as such in Bacteria and Eucarya. The latter is supported by initial data base searches of Galperin et al (22) who identified gene homologs of the unusual Class I FBP aldolase gene (dhnA) of E. coli in the sequenced archaeal genomes.…”

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confidence: 99%

Archaeal Fructose-1,6-bisphosphate Aldolases Constitute a New Family of Archaeal Type Class I Aldolase

Siebers

Brinkmann

Dörr

et al. 2001

Journal of Biological Chemistry

101

102

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Fructose-1,6-bisphosphate (FBP) aldolase activity has been detected previously in several Archaea. However, no obvious orthologs of the bacterial and eucaryal Class I and II FBP aldolases have yet been identified in sequenced archaeal genomes. Based on a recently described novel type of bacterial aldolase, we report on the identification and molecular characterization of the first archaeal FBP aldolases. We have analyzed the FBP aldolases of two hyperthermophilic Archaea, the facultatively heterotrophic Crenarchaeon Thermoproteus tenax and the obligately heterotrophic Euryarchaeon Pyrococcus furiosus. For enzymatic studies the fba genes of T. tenax and P. furiosus were expressed in Escherichia coli. The recombinant FBP aldolases show preferred substrate specificity for FBP in the catabolic direction and exhibit metal-independent Class I FBP aldolase activity via a Schiff-base mechanism. Transcript analyses reveal that the expression of both archaeal genes is induced during sugar fermentation. Remarkably, the fbp gene of T. tenax is co-transcribed with the pfp gene that codes for the reversible PP i -dependent phosphofructokinase. As revealed by phylogenetic analyses, orthologs of the T. tenax and P. furiosus enzyme appear to be present in almost all sequenced archaeal genomes, as well as in some bacterial genomes, strongly suggesting that this new enzyme family represents the typical archaeal FBP aldolase. Because this new family shows no significant sequence similarity to classical Class I and II enzymes, a new name is proposed, archaeal type Class I FBP aldolases (FBP aldolase Class IA).Fructose-1,6-bisphosphate (FBP) 1 aldolase (EC 4.1.2.13) catalyzes the reversible aldol condensation of glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) yielding FBP. The enzyme fulfills an amphibolic function being involved in catabolic (glycolysis) as well as anabolic pathways (gluconeogenesis and Calvin cycle). In spite of this central function in carbohydrate metabolism, up to now no archaeal genes coding for the respective enzyme activities have been analyzed.Two distinct classes of FBP aldolases occur in nature, which differ in their enzymatic mechanisms (1-4). Class I FBP aldolases form a Schiff-base intermediate between the carbonyl substrate (FBP and DHAP) and the ⑀-amino group of the active site lysine residue and are inactivated by borohydride (NaBH 4 ), whereas Class II FBP aldolases depend on divalent metal ions to stabilize the carbanion intermediate and are, therefore, inhibited by EDTA. Class II enzymes of bacterial and eucaryal origin generally form dimers with a subunit molecular mass of ϳ40 kDa, whereas the Class I pendants are heterogeneous. Eucaryal aldolases are homomeric tetramers with a subunit molecular mass of ϳ40 kDa, and for bacterial enzymes oligomeric arrangements from monomer to decamer and subunit molecular masses of 27-40 kDa have been described (5, 6).Sequence comparisons of Class I and II FBP aldolases revealed no detectable sequence homology, suggesting convergent evolut...

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Enzymes of gluconeogenesis in the autotroph Methanobacterium thermoautotrophicum

Cited by 44 publications

References 9 publications

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

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

An unusual class I (Schiff base) fructose‐1,6‐bisphosphate aldolase from the halophilic archaebacterium Haloarcula vallismortis

Archaeal Fructose-1,6-bisphosphate Aldolases Constitute a New Family of Archaeal Type Class I Aldolase

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