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Query: UNIPROT:P06889 (Mol)
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The multiplication of malaria parasites within red blood cells is energy dependent. Since these parasites lack a functional tricarboxylic acid cycle, the energy needs of the parasite are met by anaerobic glycolysis of exogenous glucose. High levels of glycolytic enzymes such as fructose-1,6-diphosphate aldolase, phosphoglycerate kinase and pyruvate kinase have been detected in infected erythrocytes. Here we report a 4-9 times increase in glucose phosphate isomerase (GPI) activity of infected erythrocytes over that of normal erythrocytes. This increase is of parasitic origin, as additional enzyme bands were observed in lysates of infected erythrocytes. The expression of GPI parallels parasite maturation and reaches a maximum at the trophozoite/schizont stage. Two distinct but closely related activity patterns consisting of 3-4 GPI isoenzymes (not shown in normal erythrocytes) with neutral to weakly acidic isoelectric points were observed in 6 P. falciparum isolates tested by isoelectric focusing. The purified P. falciparum GPI has an apparent size of 66 kDa. No size variation was observed in the 6 P. falciparum isolates studied. Furthermore, antiserum raised against this protein in BALB/c mice specifically inhibits parasite encoded GPI activity while no effect was observed on host enzyme activity.
Mol Biochem Parasitol 1992 Sep
PMID:Identification and purification of glucose phosphate isomerase of Plasmodium falciparum. 143 56

The reversible conversion between D-mannose 6-phosphate and D-fructose 6-phosphate catalyzed by yeast phosphomannoisomerase was studied by phase sensitive 2D 13C-(1H) EXSY NMR spectroscopy at 100.623 MHz, using 13C enriched substrates in the C2 position of the D-hexose 6-phosphates. The unique pair of isomerization cross-peaks observed in the 2D EXSY map correlates the 13C2 resonances of the beta-anomers of both D-[2-13C]-mannose 6-phosphate and D-[213C]-fructose 6-phosphate. This indicates that phosphomannoisomerase specifically catalyzes the reversible conversion between beta-D-mannose 6-phosphate and beta-D-fructose 6-phosphate. Since phosphoglucoisomerase was recently found to catalyze specifically the interconversion of alpha-D-glucose 6-phosphate and beta-D-fructose 6-phosphate, the beta-anomer of the ketohexose ester could be directly channeled in a multi-enzyme system involving phosphoglucoisomerase, phosphomannoisomerase and phosphofructokinase.
Mol Cell Biochem 1992 Oct 07
PMID:Dual anomeric specificity of phosphomannoisomerase assessed by 2D phase sensitive 13C EXSY NMR. 144 58

The gene encoding a cytosolic isozyme of phosphoglucose isomerase (PGI, EC 5.3.1.9) was isolated from Clarkia lewisii, a wild flower native to California, and the structure and sequence of the entire coding region determined. PGI catalyzes an essential step in glycolysis and carbohydrate biosynthesis in plants. Spanning about 6 kb, the gene has 23 exons and 22 introns, the highest number yet reported in plants. The exons range in size from 43 to 156 nt and encode a protein of 569 amino acids. The protein is about 44-46% identical to the inferred protein sequences of pig, Escherichia coli and Saccharomyces cerevisiae. All of the introns are bordered with the consensus 5'-GT...AG-3' dinucleotides. The longest intron includes a large stem-loop structure bounded by a perfect 9 nt direct repeat. We cloned the PGI gene from a genomic library prepared from a single plant of known PGI genotype. The locus and allele of the clone were identified by matching restriction fragments to fragments from genetically defined genomic DNAs by Southern hybridization.
Plant Mol Biol 1992 Aug
PMID:Molecular analysis of the plant gene encoding cytosolic phosphoglucose isomerase. 164 81

The exchange of protons and deuterons by phosphoglucoisomerase during the single passage conversion of D-[2-13C,1-2H]fructose 6-phosphate in H2O or D-[2-13C]fructose 6-phosphate in D2O to D-[2-13C]glucose 6-phosphate, as coupled with the further generation of 6-phospho-D-[2-13C]gluconate in the presence of excess glucose-6-phosphate dehydrogenase was investigated by 13C NMR spectroscopy of the latter metabolite. In H2O, the intramolecular deuteron transfer from the C1 of D-fructose 6-phosphate to the C2 of D-glucose 6-phosphate amounted to 65%, a value only slightly lower than the 72% intramolecular proton transfer in D2O. Both percentages, especially the latter one, were lower than those previously recorded during the single passage conversion of D-[1-13C,2-2H]glucose 6-phosphate in H2O or D-[1-13C]glucose 6-phosphate in D2O to D-fructose 6-phosphate and then to D-fructose 1,6-bisphosphate. These differences indicate that the sequence of interactions between the hexose esters and the binding sites of phosphoglucoisomerase is not strictly in mirror image during, respectively, the conversion of the aldose phosphate to ketose phosphate and the opposite process.
Mol Cell Biochem 1991 May 15
PMID:Phosphoglucoisomerase-catalyzed interconversion of hexose phosphates. Study by 13C NMR of proton and deuteron exchange. 164 80

The rag2 mutant of Kluyveromyces lactis cannot grow on glucose when mitochondrial functions are blocked by various mitochondrial inhibitors, suggesting the presence of a defect in the fermentation pathway. The RAG2 gene has been cloned from a K. lactis genomic library by complementation of the rag2 mutation. The amino acid sequence of the RAG2 protein deduced from the nucleotide sequence of the cloned RAG2 gene shows homology to the sequences of known phosphoglucose isomerases (PGI and PHI). In vivo complementation of the pgi1 mutation in Saccharomyces cerevisiae by the cloned RAG2 gene, together with measurements of specific PGI activities and the detection of PGI proteins, confirm that the RAG2 gene of K. lactis codes for the phosphoglucose isomerase enzyme. Complete loss of PGI activity observed when the coding sequence of RAG2 was disrupted leads us to conclude that RAG2 is the only gene that codes for phosphoglucose isomerase in K. lactis. The RAG2 gene of K. lactis is expressed constitutively, independently of the growth substrates (glycolytic or gluconeogenic). Unlike the pgi1 mutants of S. cerevisiae, the K. lactis rag2 mutants can still grow on glucose, however they do not produce ethanol.
Mol Gen Genet 1991 Sep
PMID:A phosphoglucose isomerase gene is involved in the Rag phenotype of the yeast Kluyveromyces lactis. 189 11

The discrimination between the isotopes of hydrogen in the reaction catalyzed by yeast phosphoglucoisomerase is examined by NMR, as well as by spectrofluorometric or radioisotopic methods. The monodirectional conversion of D-glucose 6-phosphate to D-fructose 6-phosphate displays a lower maximal velocity with D-[2-2H]glucose 6-phosphate than unlabelled D-glucose 6-phosphate, with little difference in the affinity of the enzyme for these two substrates. About 72% of the deuterium located on the C2 of D-[1-13C,2-2H]glucose 6-phosphate is transferred intramolecularly to the C1 of D-[1-13C,1-2H]fructose 6-phosphate. The velocity of the monodirectional conversion of D-[U-14C]glucose 6-phosphate (or D-[2-3H]glucose 6-phosphate) to D-fructose 6-phosphate is virtually identical in H2O and D2O, respectively, but is four times lower with the tritiated than 14C-labelled ester. In the monodirectional reaction, the intramolecular transfer from the C2 of D-[2-3H]glucose 6-phosphate is higher in the presence of D2O than H2O. Whereas prolonged exposure of D-[1-13C]glucose 6-phosphate to D2O, in the presence of phosphoglucoisomerase, leads to the formation of both D-[1-13C,2-2H]glucose 6-phosphate and D-[1-13C,1-2H]fructose 6-phosphate, no sizeable incorporation of dueterium from D2O on the C1 of D-[1-13C]fructose 1,6-bisphosphate is observed when the monodirectional conversion of D-[1-13C]glucose 6-phosphate occurs in the concomitant presence of phosphoglucoisomerase and phosphofructokinase. The latter finding contrasts with the incorporation of hydrogen from 1H2O or tritium from 3H2O in the monodirectional conversion of D-[2-3H]glucose 6-phosphate and unlabelled D-glucose 6-phosphate, respectively, to their corresponding ketohexose esters.
Mol Cell Biochem 1990 Mar 27
PMID:Phosphoglucoisomerase-catalyzed interconversion of hexose phosphates: isotopic discrimination between hydrogen and deuterium. 234 41

The nucleotide sequence of the gene encoding the glycolytic enzyme phosphoglucose isomerase (PGI) from Escherichia coli is presented. The gene encodes a polypeptide of 549 amino acids. The transcriptional start point of the gene was determined and found to lie within a consensus promoter region. The amino acid sequence derived from the E. coli PGI gene can be aligned without insertions or deletions to the predicted amino acid sequence of a nuclear-encoded chloroplast isozyme of PGI from a higher plant, and the two sequences have a similarity of 87.6%. The amino acid sequence similarity between E. coli and that predicted from cDNA sequences for mouse and pig PGI is approximately 65%.
Mol Gen Genet 1989 May
PMID:Isolation and characterization of the phosphoglucose isomerase gene from Escherichia coli. 254 64

Anaerobiosis results in the selective synthesis of a particular set of polypeptides in the maize root including the two alcohol dehydrogenases (Sachs, M. M., Freeling, M., and Okimoto, R. (1980) Cell 20, 761-768), pyruvate decarboxylase (Wignarajah, K., and Greenway, H. (1976) New Phytol. 77, 575-584; Laszlo, A., and St. Lawrence, P. (1983) Mol. Gen. Genet. 192, 110-117), glucose phosphate isomerase (Kelley, P. M., and Freeling, M. (1984) J. Biol. Chem. 259, 673-677) and aldolase (Kelley, P. M., and Freeling, M. (1984) J. Biol. Chem. 259, 14180-14183). This report describes the identification and characterization of cDNA clones to five different mRNA species induced upon anaerobic shock. Immunoprecipitation of hybrid-selected translation polypeptides has determined the identity of the cDNA clone for fructose-1,6-diphosphate aldolase mRNA. Quantitative hybridization analysis of anaerobic mRNAs using the cDNA clones has shown that there is not a simultaneous accumulation of anaerobic mRNAs. Upon reintroduction of air, the anaerobic mRNAs disappear rapidly and at approximately the same rate. A translocation line that generates progeny that contain 1, 2, and 3 doses of the long arm of chromosome one (1L) allowed us to test for clustering of the anaerobic genes; two of the anaerobic genes tested do not reside with Adh 1 and Phi 1 on the long arm of chromosome 1.
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PMID:Coordinate induction of alcohol dehydrogenase 1, aldolase, and other anaerobic RNAs in maize. 258 Aug 29

The teleost Fundulus heteroclitus (L.) possesses two loci, Gpi-A and Gpi-B, for the glycolytic enzyme, glucose-phosphate isomerase (GPI; D-glucose-6-phosphate ketol-isomerase; E.C. 5.3.1.9). The Gpi-B locus is polymorphic in Fundulus, with two common alleles, Gpi-Bb and Gpi-Bc, distributed in a clinal manner in populations along the east coast of North America. Since this clinal distribution is strongly correlated with a temperature gradient, we asked whether the GPI-B2 allozymes were functionally adapted to the thermal environment in which a given phenotype predominated. The two major GPI-B2 allozymes were purified to homogeneity and were characterized as to molecular weight, isoelectric pH, thermal denaturation, and kinetic parameters. Both GPI-Bb2 and GPI-Bc2 allozymes have molecular masses of 110 kD, and they have isoelectric pHs of 6.4 and 6.6, respectively. The GPI-Bb2 allozyme was more stable to thermal denaturation than was the GPI-Bc2 enzyme. Kinetic properties of the allelic isozymes were investigated both as a function of pH and as a function of temperature. At 25 degrees C, over the pH range considered, there were no significant differences between allozymes, either in Km for fructose-6-phosphate or in Ki for 6-phosphogluconate, but apparent Vmax values differed between pH 7.5 and pH 8.5. All steady-state kinetic parameters showed strong temperature dependence, but the allozymes differed only in the Ki for 6-phosphogluconate at temperatures greater than 30 degrees C. On the basis of the observed structural and functional differences alluded to above, the hypothesis that the major allelic isozymes of the Gpi-B locus were functionally equivalent was rejected. However, it is not yet known whether these structural and functional differences have any significance at higher levels of biological organization.
Mol Biol Evol 1989 Mar
PMID:Structural and functional differentiation of two clinally distributed glucosephosphate isomerase allelic isozymes from the teleost Fundulus heteroclitus. 271 17

The rate of conversion of D-glucose 6-phosphate to D-fructose 6-phosphate as catalyzed by yeast phosphoglucoisomerase is about fourfold lower when 3H, rather than 1H, is present on the C2 of D-glucose 6-phosphate. This difference appears to be due mainly to a change in maximal velocity, rather than affinity. Phosphoglucoisomerase also distinguishes between 1H and 3H in terms of either their intramolecular transfer from C2 to C1 or their incorporation from water on the C1 of D-fructose 6-phosphate.
Mol Cell Biochem 1989 Aug 15
PMID:Phosphoglucoisomerase-catalyzed interconversion of hexose-phosphates. Isotopic discrimination between hydrogen and tritium. 277 47


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