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

Krishnan, Gomathi; Altekar, Wijaya

doi:10.1111/j.1432-1033.1991.tb15712.x

Cited by 37 publications

(16 citation statements)

References 48 publications

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“…vallismortis and Tco. kodakarensis (130,133). Despite the lack of significant overall sequence identity, the structural similarity of the two types of FBPA I enzymes suggests a common ancestry and, thus, homology (135,136).…”

Section: Fructose-16-bisphosphate Aldolase (Catabolic)mentioning

confidence: 99%

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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

271

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: Fructose-16-bisphosphate Aldolase (Catabolic)mentioning

confidence: 99%

“…furiosus, and Tco. kodakarensis (126,130,132,133). Two classes of FBPAs, which differ with respect to reaction mechanisms and distributions in the biosphere, have been identified (for literature, see reference 134).…”

Section: Fructose-16-bisphosphate Aldolase (Catabolic)mentioning

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

271

294

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“…Although several enzymes of the proposed modified EM pathway in haloarchaea, ketohexokinase, 1-PFK, and class I and class II type FBA, have been purified (21,31,36,37), the genes encoding these enzymes have not been identified so far, and their functional involvement in fructose catabolism has not been demonstrated. Recently, the fructose-specific upregulation of a gene (HVO_1500) encoding putative 1-PFK has been reported for H. volcanii, and the role of a transcription regulator (GlpR) in fructose catabolism has been analyzed (39).…”

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confidence: 99%

Fructose Degradation in the Haloarchaeon Haloferax volcanii Involves a Bacterial Type Phosphoenolpyruvate-Dependent Phosphotransferase System, Fructose-1-Phosphate Kinase, and Class II Fructose-1,6-Bisphosphate Aldolase

2012

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The halophilic archaeon Haloferax volcanii utilizes fructose as a sole carbon and energy source. Genes and enzymes involved in fructose uptake and degradation were identified by transcriptional analyses, deletion mutant experiments, and enzyme characterization. During growth on fructose, the gene cluster HVO_1495 to HVO_1499, encoding homologs of the five bacterial phosphotransferase system (PTS) components enzyme IIB (EIIB), enzyme I (EI), histidine protein (HPr), EIIA, and EIIC, was highly upregulated as a cotranscript. The in-frame deletion of HVO_1499, designated ptfC (ptf stands for phosphotransferase system for fructose) and encoding the putative fructose-specific membrane component EIIC, resulted in a loss of growth on fructose, which could be recovered by complementation in trans. Transcripts of HVO_1500 (pfkB) and HVO_1494 (fba), encoding putative fructose-1-phosphate kinase (1-PFK) and fructose-1,6-bisphosphate aldolase (FBA), respectively, as well as 1-PFK and FBA activities were specifically upregulated in fructose-grown cells. pfkB and fba knockout mutants did not grow on fructose, whereas growth on glucose was not inhibited, indicating the functional involvement of both enzymes in fructose catabolism. Recombinant 1-PFK and FBA obtained after homologous overexpression were characterized as having kinetic properties indicative of functional 1-PFK and a class II type FBA. From these data, we conclude that fructose uptake in H. volcanii involves a fructose-specific PTS generating fructose-1-phosphate, which is further converted via fructose-1,6-bisphosphate to triose phosphates by 1-PFK and FBA. This is the first report of the functional involvement of a bacterial-like PTS and of class II FBA in the sugar metabolism of archaea. Various halophilic archaea, including Haloarcula marismortui and Haloferax volcanii, have been reported to utilize fructose as carbon and energy sources (29,34,46). The pathway of fructose degradation has been studied so far mainly in the Haloarcula species H. vallismortis and H. marismortui (6,7,29). On the basis of enzyme analyses, a modified version of the Embden-Meyerhof (EM) pathway has been proposed, involving fructose phosphorylation via ketohexokinase to fructose-1-phosphate, which is further phosphorylated to fructose-1,6-bisphosphate (FBP) by fructose-1-phosphate kinase (1-PFK). FBP is subsequently cleaved by FBP aldolase (FBA) to dihydroxyacetone phosphate and glyceraldehyde-3-phosphate, which are degraded to pyruvate following classical enzymes of the EM pathway. In vivo evidence for the operation of an EM pathway in fructose degradation was demonstrated in H. marismortui by labeling experiments with [13 C]fructose using growing cultures (29). With the same labeling techniques, glucose degradation in H. marismortui was shown to be degraded in vivo via an Entner-Doudoroff (ED) type pathway (29), which is in accordance with the proposed semiphosphorylated ED pathway for glucose degradation in haloarchaea (43).Although several enzymes of the proposed modified EM pathway...

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

Cited by 37 publications

References 48 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

Fructose Degradation in the Haloarchaeon Haloferax volcanii Involves a Bacterial Type Phosphoenolpyruvate-Dependent Phosphotransferase System, Fructose-1-Phosphate Kinase, and Class II Fructose-1,6-Bisphosphate Aldolase

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

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