scholarly journals Transaldolase ofMethanocaldococcus jannaschii

Archaea ◽  
2004 ◽  
Vol 1 (4) ◽  
pp. 255-262 ◽  
Author(s):  
Tim Soderberg ◽  
Robert C. Alver
Keyword(s):  
Pentose Phosphate Pathway ◽  
Gel Filtration ◽  
Pentose Phosphate ◽  
Direct Application ◽  
Maximal Velocity ◽  
Native Form ◽  
Methanocaldococcus Jannaschii ◽  
Reading Frame ◽  
Michaelis Constants ◽  
Aldolase Activity

TheMethanocaldococcus jannaschiigenome contains putative genes for all four nonoxidative pentose phosphate pathway enzymes. Open reading frame (ORF) MJ0960 is a member of themipB/talCfamily of ‘transaldolase-like’ genes, so named because of their similarity to the well-characterized transaldolase B gene family. However, recently, it has been reported that both themipBand thetalCgenes fromEscherichia coliencode novel enzymes with fructose-6-phosphate aldolase activity, not transaldolase activity (Schürmann and Sprenger 2001). The same study reports that other members of themipB/talCfamily appear to encode transaldolases. To confirm the function of MJ0960 and to clarify the presence of a nonoxidative pentose phosphate pathway inM. jannaschii, we have cloned ORF MJ0960 fromM. jannaschiigenomic DNA and purified the recombinant protein. MJ0960 encodes a transaldolase and displays no fructose-6-phosphate aldolase activity. It retained full activity for 4 h at 80 °C, and for 3 weeks at 25 °C.Methanocaldococcus jannaschiitransaldolase has a maximal velocity (Vmax) of 1.0 ± 0.2 µmol min–1mg–1at 25 °C, whereasVmax= 12.0 ± 0.5 µmol min–1mg–1at 50 °C. Apparent Michaelis constants at 50 °C wereKm= 0.65 ± 0.09 mM for fructose-6-phosphate andKm= 27.8 ± 4.3 µM for erythrose-4-phosphate. When ribose-5-phosphate replaced erythrose-4-phosphate as an aldose acceptor,Vmaxdecreased twofold, whereas theKmwas 150-fold higher. The molecular mass of the active enzyme is 271 ± 27 kDa as estimated by gel filtration, whereas the predicted monomer size is 23.96 kDa, suggesting that the native form of the protein is probably a decamer. A readily available source of thermophilic pentose phosphate pathway enzymes including transaldolase may have direct application in enzymatic biohydrogen production.

scholarly journals Regulation of the pentose phosphate cycle Cofactor that controls the inhibition of glucose-6-phosphate dehydrogenase by NADPH in rat liver

1986 ◽  
Vol 239 (3) ◽  
pp. 553-558 ◽  
Author(s):  
M Nogueira ◽  
G Garcia ◽  
C Mejuto ◽  
M Freire
Keyword(s):  
Ion Exchange ◽  
Rat Liver ◽  
Pentose Phosphate Pathway ◽  
Reductase Activity ◽  
Gel Filtration ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Pentose Phosphate ◽  
Glutathione Reductase Activity ◽  
Glucose 6 Phosphate Dehydrogenase

A cofactor of Mr 10(4), characterized as a polypeptide, was found to co-operate with GSSG to prevent the inhibition of glucose-6-phosphate dehydrogenase by NADPH, in order to ensure the operation of the oxidative phase of the pentose phosphate pathway, in rat liver [Eggleston & Krebs (1974) Biochem. J. 138, 425-435; Rodriguez-Segade, Carrion & Freire (1979) Biochem. Biophys. Res. Commun. 89, 148-154]. This cofactor has now been partially purified by ion-exchange chromatography and molecular gel filtration, and characterized as a protein of Mr 10(5). The lighter cofactor reported previously was apparently the result of proteolytic activity generated during the tissue homogenization. The heavier cofactor was unstable, and its amount increased in livers of rats fed on carbohydrate-rich diet. Since the purified cofactor contained no glutathione reductase activity, the involvement of this enzyme in the deinhibitory mechanism of glucose-6-phosphate dehydrogenase by NADPH should be ruled out.

scholarly journals Complex Metabolic Phenotypes Caused by a Mutation in yjgF, Encoding a Member of the Highly Conserved YER057c/YjgF Family of Proteins

1998 ◽  
Vol 180 (24) ◽  
pp. 6519-6528 ◽  
Author(s):  
Jodi L. Enos-Berlage ◽  
Mark J. Langendorf ◽  
Diana M. Downs
Keyword(s):  
Pentose Phosphate Pathway ◽  
Biosynthetic Pathway ◽  
Genetic Characterization ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Phenotypic Characterization ◽  
Reading Frame ◽  
Wide Range ◽  
Isoleucine Biosynthesis

ABSTRACT The oxidative pentose phosphate pathway is required for function of the alternative pyrimidine biosynthetic pathway, a pathway that allows thiamine synthesis in the absence of the PurF enzyme inSalmonella typhimurium. Mutants that no longer required function of the oxidative pentose phosphate pathway for thiamine synthesis were isolated. Further phenotypic analyses of these mutants demonstrated that they were also sensitive to the presence of serine in the medium, suggesting a partial defect in isoleucine biosynthesis. Genetic characterization showed that these pleiotropic phenotypes were caused by null mutations in yjgF, a previously uncharacterized open reading frame encoding a hypothetical 13.5-kDa protein. The YjgF protein belongs to a class of proteins of unknown function that exhibit striking conservation across a wide range of organisms, from bacteria to humans. This work represents the first detailed phenotypic characterization of yjgF mutants in any organism and provides important clues as to the function of this highly conserved class of proteins. Results also suggest a connection between function of the isoleucine biosynthetic pathway and the requirement for the pentose phosphate pathway in thiamine synthesis.

scholarly journals Ribose-5-Phosphate Biosynthesis in Methanocaldococcus jannaschii Occurs in the Absence of a Pentose-Phosphate Pathway

2005 ◽  
Vol 187 (21) ◽  
pp. 7382-7389 ◽  
Author(s):  
Laura L. Grochowski ◽  
Huimin Xu ◽  
Robert H. White
Keyword(s):  
Recent Work ◽  
Pentose Phosphate Pathway ◽  
Methanogenic Archaea ◽  
Protein Product ◽  
Pentose Phosphate ◽  
The Other ◽  
Methanocaldococcus Jannaschii ◽  
Cell Extracts ◽  
Ribulose Monophosphate Pathway ◽  
Sugar Phosphates

ABSTRACT Recent work has raised a question as to the involvement of erythrose-4-phosphate, a product of the pentose phosphate pathway, in the metabolism of the methanogenic archaea (R. H. White, Biochemistry 43:7618-7627, 2004). To address the possible absence of erythrose-4-phosphate in Methanocaldococcus jannaschii, we have assayed cell extracts of this methanogen for the presence of this and other intermediates in the pentose phosphate pathway and have determined and compared the labeling patterns of sugar phosphates derived metabolically from [6,6-2H2]- and [U-13C]-labeled glucose-6-phosphate incubated with cell extracts. The results of this work have established the absence of pentose phosphate pathway intermediates erythrose-4-phosphate, xylose-5-phosphate, and sedoheptulose-7-phosphate in these cells and the presence of d-arabino-3-hexulose-6-phosphate, an intermediate in the ribulose monophosphate pathway. The labeling of the d-ara-bino-3-hexulose-6-phosphate, as well as the other sugar-Ps, indicates that this hexose-6-phosphate was the precursor to ribulose-5-phosphate that in turn was converted into ribose-5-phosphate by ribose-5-phosphate isomerase. Additional work has demonstrated that ribulose-5-phosphate is derived by the loss of formaldehyde from d-arabino-3-hexulose-6-phosphate, catalyzed by the protein product of the MJ1447 gene.

Purification and kinetic characterization of hexokinase and glucose-6-phosphate dehydrogenase fromSchizosaccharomyces pombe

1998 ◽  
Vol 76 (1) ◽  
pp. 107-113 ◽  
Author(s):  
C Stan Tsai ◽  
Q Chen
Keyword(s):  
Pentose Phosphate Pathway ◽  
Ternary Complex ◽  
Kinetic Studies ◽  
Product Inhibition ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Phosphoryl Group ◽  
Maximal Velocity ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Yeast Hexokinase

Hexokinase and D-glucose-6-phosphate dehydrogenase (G6PDH) from Schizosaccharomyces pombe have been purified 250-fold by an identical three-step. Both enzymes are dimeric with a molecular mass of 88 kDa for the kinase and 112 kDa for the dehydrogenase. Steady-state kinetic studies were performed on hexokinase and G6PDH, which form the glucose phosphate branch of the oxidative pentose phosphate pathway of S. pombe (fission yeast). Hexokinase promotes Mg2+-activated phosphorylation of D-glucose by the equilibrium random Bi Bi mechanism with formation of the abortive enzyme-ADP-glucose complex. ADP inhibits the kinase competitively versus ATP and noncompetitively versus D-glucose. The Mg2+activation of hexokinase is associated with an increase in the maximal velocity by its interaction with the ternary complex to facilitate the transfer of the phosphoryl group. G6PDH catalyzes NADP+-linked oxidation of D-glucose-6-phosphate by the ordered Bi Bi mechanism with NADP+as the leading reactant. High NADP+concentration inhibits the dehydrogenase by forming the dead-end ternary complex. In addition, G6PDH is also subjected to product inhibition by NADPH and noncompetitive inhibition by A(G)TP. Thus, the oxidative pentose phosphate pathway in S. pombe may be regulated via inhibition of hexokinase by ADP in conjunction with inhibition of G6PDH by NADPH and ATP.Key words: yeast hexokinase, glucose-6-phosphate dehydrogenase.

scholarly journals The Ribulose Monophosphate Pathway Substitutes for the Missing Pentose Phosphate Pathway in the Archaeon Thermococcus kodakaraensis

2006 ◽  
Vol 188 (13) ◽  
pp. 4698-4704 ◽  
Author(s):  
Izumi Orita ◽  
Takaaki Sato ◽  
Hiroya Yurimoto ◽  
Nobuo Kato ◽  
Haruyuki Atomi ◽  
...  
Keyword(s):  
Pentose Phosphate Pathway ◽  
Deletion Mutant ◽  
Minimal Medium ◽  
Catalytic Properties ◽  
Pentose Phosphate ◽  
Genetic Approach ◽  
Reading Frame ◽  
Ribulose Monophosphate Pathway ◽  
Pentose Phosphate Pathways ◽  
Genome Analyses

ABSTRACT The ribulose monophosphate (RuMP) pathway, involving 3-hexulose-6-phosphate synthase (HPS) and 6-phospho-3-hexuloisomerase (PHI), is now recognized as a widespread prokaryotic pathway for formaldehyde fixation and detoxification. Interestingly, HPS and PHI homologs are also found in a variety of archaeal strains, and recent biochemical and genome analyses have raised the possibility that the reverse reaction of formaldehyde fixation, i.e., ribulose 5-phosphate (Ru5P) synthesis from fructose 6-phosphate, may function in the biosynthesis of Ru5P in some archaeal strains whose pentose phosphate pathways are imperfect. In this study, we have taken a genetic approach to address this possibility by using the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1. This strain possesses a single open reading frame (TK0475) encoding an HPS- and PHI-fused protein. The recombinant HPS-PHI-fused enzyme exhibited the expected HPS and PHI activities in both directions (formaldehyde fixing and Ru5P synthesizing). The TK0475 deletion mutant Δhps-phi-7A did not exhibit any growth in minimal medium, while growth of the mutant strain could be recovered by the addition of nucleosides to the medium. This auxotrophic phenotype together with the catalytic properties of the HPS-PHI-fused enzyme reveal that HPS and PHI are essential for the biosynthesis of Ru5P, the precursor of nucleotides, showing that the RuMP pathway is the only relevant pathway for Ru5P biosynthesis substituting for the classical pentose phosphate pathway missing in this archaeon.

scholarly journals Systematic Identification of Regulators of Oxidative Stress Reveals Non-canonical Roles for Peroxisomal Import and the Pentose Phosphate Pathway

Cell Reports ◽  
2020 ◽  
Vol 30 (5) ◽  
pp. 1417-1433.e7 ◽  
Author(s):  
Michael M. Dubreuil ◽  
David W. Morgens ◽  
Kanji Okumoto ◽  
Masanori Honsho ◽  
Kévin Contrepois ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Pentose Phosphate Pathway ◽  
Pentose Phosphate ◽  
Systematic Identification

scholarly journals Geranylgeranylacetone attenuates cerebral ischemia–reperfusion injury in rats through the augmentation of HSP 27 phosphorylation: a preliminary study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Kazuya Matsuo ◽  
Kohkichi Hosoda ◽  
Jun Tanaka ◽  
Yusuke Yamamoto ◽  
Taichiro Imahori ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Reperfusion Injury ◽  
Pentose Phosphate Pathway ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Pentose Phosphate ◽  
Cerebral Ischemia Reperfusion ◽  
Hsp27 Phosphorylation ◽  
Cerebral Ischemia Reperfusion Injury ◽  
Preliminary Study

Abstract Background We previously reported that heat shock protein 27 (HSP27) phosphorylation plays an important role in the activation of glucose-6-phosphate dehydrogenase (G6PD), resulting in the upregulation of the pentose phosphate pathway and antioxidant effects against cerebral ischemia–reperfusion injury. The present study investigated the effect of geranylgeranylacetone, an inducer of HSP27, on ischemia–reperfusion injury in male rats as a preliminary study to see if further research of the effects of geranylgeranylacetone on the ischemic stroke was warranted. Methods In all experiments, male Wistar rats were used. First, we conducted pathway activity profiling based on a gas chromatography–mass spectrometry to identify ischemia–reperfusion-related metabolic pathways. Next, we investigated the effects of geranylgeranylacetone on the pentose phosphate pathway and ischemia–reperfusion injury by real-time polymerase chain reaction (RT-PCR), immunoblotting, and G6PD activity, protein carbonylation and infarct volume analysis. Geranylgeranylacetone or vehicle was injected intracerebroventricularly 3 h prior to middle cerebral artery occlusion or sham operation. Results Pathway activity profiling demonstrated that changes in the metabolic state depended on reperfusion time and that the pentose phosphate pathway and taurine-hypotaurine metabolism pathway were the most strongly related to reperfusion among 137 metabolic pathways. RT-PCR demonstrated that geranylgeranylacetone did not significantly affect the increase in HSP27 transcript levels after ischemia–reperfusion. Immunoblotting showed that geranylgeranylacetone did not significantly affect the elevation of HSP27 protein levels. However, geranylgeranylacetone significantly increase the elevation of phosphorylation of HSP27 after ischemia–reperfusion. In addition, geranylgeranylacetone significantly affected the increase in G6PD activity, and reduced the increase in protein carbonylation after ischemia–reperfusion. Accordingly, geranylgeranylacetone significantly reduced the infarct size (median 31.3% vs 19.9%, p = 0.0013). Conclusions As a preliminary study, these findings suggest that geranylgeranylacetone may be a promising agent for the treatment of ischemic stroke and would be worthy of further study. Further studies are required to clearly delineate the mechanism of geranylgeranylacetone-induced HSP27 phosphorylation in antioxidant effects, which may guide the development of new approaches for minimizing the impact of cerebral ischemia–reperfusion injury.

scholarly journals Pentose Phosphate Pathway Reactions in Photosynthesizing Cells

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1547
Author(s):  
Thomas D. Sharkey
Keyword(s):  
Pentose Phosphate Pathway ◽  
Strong Association ◽  
Pentose Phosphate ◽  
Critical Component ◽  
Reaction Sequence ◽  
Response To Stress ◽  
Labeling Pattern

The pentose phosphate pathway (PPP) is divided into an oxidative branch that makes pentose phosphates and a non-oxidative branch that consumes pentose phosphates, though the non-oxidative branch is considered reversible. A modified version of the non-oxidative branch is a critical component of the Calvin–Benson cycle that converts CO2 into sugar. The reaction sequence in the Calvin–Benson cycle is from triose phosphates to pentose phosphates, the opposite of the typical direction of the non-oxidative PPP. The photosynthetic direction is favored by replacing the transaldolase step of the normal non-oxidative PPP with a second aldolase reaction plus sedoheptulose-1,7-bisphosphatase. This can be considered an anabolic version of the non-oxidative PPP and is found in a few situations other than photosynthesis. In addition to the strong association of the non-oxidative PPP with photosynthesis metabolism, there is recent evidence that the oxidative PPP reactions are also important in photosynthesizing cells. These reactions can form a shunt around the non-oxidative PPP section of the Calvin–Benson cycle, consuming three ATP per glucose 6-phosphate consumed. A constitutive operation of this shunt occurs in the cytosol and gives rise to an unusual labeling pattern of photosynthetic metabolites while an inducible shunt in the stroma may occur in response to stress.

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