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At least 253 records · Page 14Linked to original sources

PubMed1990

Regulation of chorismate mutase in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae ARO7 gene was cloned by screening a wild-type gene bank for complementation of an aro7 auxotrophic mutant. In vitro mutagenesis of the isolated plasmid (pJFB1) gave several transformants resistant to levels of the phenylalanine analogue 2-thienylalanine inhibitory to the wild-type transformant. Chorismate mutase assays indicated that two of the mutants (J14-26IV6 and J14-26IV9) were resistant to feedback inhibition by tyrosine displayed by wild-type strains. Analysis of the effect of other aromatic amino acids on chorismate mutase activity showed that tryptophan counteracted this inhibition. Analysis of the effect of tyrosine in the growth medium on enzyme activity indicated that the wild-type ARO7 gene was repressed by tyrosine, a phenomenon not previously reported. Two of the 2-thienylalanine resistant mutants (J14-26IV3 and J14-26IV9) appeared to be resistant to this repression. Transcriptional analysis confirmed that the level of ARO7 transcript decreased with increasing tyrosine concentration. In stain J14-26IV9 the ARO7 transcript level was not affected. J14-26IV9, therefore, appears to be a double mutant, resistant to both feedback inhibition and repression by tyrosine.

Chorismate Mutase↗

PubMed1993

Congenital absence of insulin cells in a neonate with diabetes mellitus and mutase-deficient methylmalonic acidaemia.

We report on a female neonate with diabetes mellitus and methylmalonic acidaemia, who died at age 16 days. Using immunocytochemistry, electron microscopy and in situ hybridisation, we were unable to demonstrate any insulin cells in the pancreatic islets. Methylmalonic acidaemia was caused by a methylmalonyl coenzyme A mutase apoenzyme defect. The metabolic crisis of the methylmalonic acidaemia aggravated the diabetes and may explain the failure of insulin therapy. Our results suggest that the infant suffered from a congenital absence of beta cells associated with a genetically transmitted mutase apoenzyme defect.

Autopsy↗

PubMed2003

Purification and characterization of homodimeric methylmalonyl-CoA mutase from Sinorhizobium meliloti.

High activity (>60 munit/mg protein) of 5'-deoxyadenosylcobalamin-dependent methylmalonyl-CoA mutase (EC 5.4.99.2) was constantly found during growth of a strain of the root-nodule-forming bacterium Sinorhizobium meliloti harboring an extra plasmid-encoded copy of the methylmalonyl-CoA-mutase-encoding bhbA gene. The enzyme was purified to homogeneity and characterized. The purified enzyme was found to be a colorless apo-form. The apparent molecular weight of the enzyme was calculated to be 165,000+/-5,000 by Superdex 200 HR gel filtration. SDS-PAGE of the purified enzyme resolved one protein band with an apparent molecular mass of 80.0+/-2.0 kDa, indicating that the S. meliloti enzyme is composed of two identical subunits. The NH(2)-terminal sequence was identical to that predicted from the bhbA nucleotide sequence. Monovalent cations were required for enzyme activity.

Apoenzymes↗

PubMed1992

Interaction of rabbit muscle enolase and 3-phosphoglycerate mutase studied by ELISA and by batch gel filtration.

The interaction of rabbit skeletal muscle enolase and 3-phosphoglycerate mutase was detected by an ELISA test, a batch gel-filtration technique, and fluorescence anisotropy measurements, and the activity of enolase was determined to be a function of mutase concentration. The apparent dissociation constant of this enzyme complex is approximately 1 microM. This value seems to be independent of the presence (in fluorescence anisotropy measurements) or the absence (in activity as well as in ELISA experiments) of fluorescein isothiocyanate used widely as a label for determining the complex formation between enzymes in fluorescence anisotropy measurements.

Animals↗

PubMed1984

The effects of anions on phosphoglycerate mutase.

Chloride (5-100 mM) can activate the phosphoglycerate mutase reaction (3-PG in equilibrium with 2-PG). I-, N0-3, or higher Cl- inhibit the mutase reaction while allowing mixing of isotope from [32P]3-PG into a large pool of 2,3-bisphosphoglycerate. p-Hydroxybenzoate inhibits without causing isotope dilution. A number of anions (p-hydroxybenzoate approximate equal to NO3- greater than Cl- greater than Tes greater than acetate) stimulate the P-glycolate activated 2,3-bisphosphoglycerate phosphatase reaction of this enzyme. The same anions inhibit competitively with P-glycolate. A kinetic analysis relates the anion effects to changes in rates of association and dissociation of substrates.

2,3-Diphosphoglycerate↗

PubMed1985

Wheat germ phosphoglycerate mutase: purification, polymorphism, and inhibition.

An improved method for purifying the bisphosphoglycerate-independent phosphoglycerate mutase from wheat germ has been devised. The method yields enzyme with a specific activity of 2,300 units/mg in 0.1 M Tris-C1 at pH 8.7 and 30 degrees C. Electrophoresis on electrofocusing and analytical polyacrylamide gels reveals only one protein band (pI = 7.3); however, under denaturing conditions (sodium dodecyl sulfate polyacrylamide gel electrophoresis), two prominent enzyme forms, with molecular masses of 63 and 74 kDa, manifest themselves along with several minor, high molecular mass components (126-141 kDa). Non-denaturing exclusion chromatography shows that both major species are catalytically active, and suggests that each species is capable of participating in reversible monomer/dimer association. Wheat germ mutase is inhibited by time-dependent reactions involving either polydentate chelators or sulfhydryl reagents.

Bisphosphoglycerate Mutase↗

PubMed1996

Phosphoglycerate mutase from Schizosaccharomyces pombe: development of an expression system and characterisation of three histidine mutants of the enzyme.

The small, monomeric, phosphoglycerate mutase (PGAM) from Schizosaccharomyces pombe has been overexpressed in a strain of Saccharomyces cerevisiae in which the gene encoding PGAM has been deleted, with a yield of purified enzyme of 10-15 mg per litre cell culture. Three mutants in which histidine residues in S. pombe PGAM have been substituted by glutamine have been purified and characterised. Two mutants (H151Q and H196Q) have kinetic and structural properties very similar to wild-type enzyme, consistent with the proposed location of these (non-conserved) histidines on the surface of the enzyme. The third mutant (H163Q) involving a histidine thought to be part of the active site has greatly reduced mutase and phosphatase activities. Mass spectrometry shows that the phosphorylated form of the H163Q is several 100-times more stable towards hydrolysis than the phosphorylated form of wild-type enzyme. The H163Q mutant appears to be structurally quite distinct from wild-type enzyme. 600 MHz 1D proton NMR spectra of good quality have been obtained for wild-type enzyme and the H151Q and H196Q mutants.

Base Sequence↗

PubMed1992

Structural modeling of the human erythrocyte bisphosphoglycerate mutase.

Using the crystallographic structure of yeast monophosphoglycerate mutase (MPGM) as a framework we constructed a three-dimensional model of the homologous human erythrocyte bisphosphoglycerate mutase (BPGM). The modeling procedure consisted of substituting 117 amino acid residues and positioning 19 C-terminal residues (unresolved in the X-ray structure) by empirical methods, followed by energy minimization. Among several differences in the active site region the most significant appears to be the replacement of Ser11 in MPGM by Gly in BPGM. The C-terminal segment, which contains mainly basic amino acids, lines the cavity of the active site. The seven amino acid residues, which have been shown to be essential for the three catalytic functions of the human BPGM, interact with the amino acids in the protein core, near the active site. In addition, a cluster of several positively charged residues, particularly arginines, has been identified at the entrance of the active site; this cluster may serve as a secondary binding site for polyanionic substrates or cofactors, as required by a two-binding-site model of the catalytic activities. This model is in agreement with recent studies of an inactive BPGM variant substituent at an Arg position situated in this positively charged cluster. The position of Cys20 in the model constructed suggests that this residue is responsible for inactivation of the enzyme by sulfhydryl reagents. Subunit interfaces have also been constructed for BPGM by analogy with MPGM and suggest that, in addition to the known dimerization of BPGM, tetramerization may occur under certain conditions.

Amino Acid Sequence↗

PubMed1979

Kinetic control of phosphoglycerate mutase from Flavobacterium sp. grown on ethylene glycol.

A species of Flavobacterium able to oxidise ethylene glycol to pyruvate via glyoxylate, glycerate, 2-phosphoglycerate and phosphoenolpyruvate exploits phosphoglycerate mutase to initiate gluconeogenesis. Partially purified phosphoglycerate mutase from this bacterium is independent of adenylate charge control but is activated by phosphoenolpyruvate. The possible significance of this regulation is discussed.

Acetyl Coenzyme A↗

PubMed1995

2,3-Bisphosphoglycerate-independent phosphoglycerate mutase is conserved among different phylogenic kingdoms.

We have previously demonstrated that maize (Zea mays) 2,3-bisphosphoglycerate-independent phosphoglycerate mutase (PGAM-i) is not related to 2,3-bisphosphoglycerate-dependent phosphoglycerate mutase. With the aid of specific anti-maize PGAM-i antibodies, we demonstrate here the presence of a closely related PGAM-i in other plants. We also describe the isolation and sequencing of a cDNA-encoding almond (Prunus amygdalus) PGAM-i that further demonstrates this relationship among plant PGAM-i. A search of the major databases for related sequences allowed us to identify some novel PGAM-i from different sources: plants (Arabidopsis thaliana, Oryza sativa and Antithamniom sp.), monera (Escherichia coli, Bacillus subtilis and Bacillus megaterium) and animals (Caenorhabditis elegans). All of these amino acid sequences share a high degree of homology with plant PGAM-i. These observations suggest that the PGAM-i from several biological kingdoms constitute a family of protein different from other proteins with related enzymatic function and arose from a common ancestral gene that has diverged throughout its evolution.

Amino Acid Sequence↗

PubMed1990

Isolation and characterization of the gene encoding the muscle-specific isozyme of human phosphoglycerate mutase.

The human muscle-specific phosphoglycerate mutase encoding gene (PGAM-M) has been cloned from a genomic cosmid library and sequenced. The sequence corresponding to the coding region was evaluated and revised by sequencing of the protein itself, fully confirming our results. The amino acid sequence of the M isozyme presented a 80.6% homology with the B isozyme (non-muscle-specific isozyme), a value higher than previously reported. The PGAM-M gene is composed of three exons, which consist of 454, 180 and 202 bp, respectively, and are separated by two introns of 103 bp and approx. 5.6 kb, respectively. Comparison of the structure of the human PGAM-M gene with that coding for human bisphosphoglycerate mutase, an erythroid-specific enzyme belonging to the same multifunctional enzyme family, revealed that the location of the second intron is similar in each gene and corresponds to a tertiary subdomain in the spatial structure of the protein. The transcription start point (tsp) in the PGAM-M gene was identified by both primer extension and S1 nuclease-protection experiments. A TATA-box-like element was observed 29 bp upstream from the tsp; the sequence ATTGG, inverse/complementary to CCAAT-box, was found 40 bp upstream from the supposed TATA box. No muscle-specific consensus sequences could be detected in the 5'-untranslated region. Only one polyadenylation AATAAA signal was observed in the short 3'-untranslated region (43 bp long). Finally, only one copy of this gene is present in the human genome instead of the several copies found for the PGAM-B gene, suggesting the possible evolutionary origin of the muscle subunit in a modified copy of the PGAM-B gene.

Amino Acid Sequence↗

PubMed1996

Site-directed mutagenesis of monofunctional chorismate mutase engineered from the E. coli P-protein.

Analysis of the active-site residues of a fully functional chorismate mutase representing the N-terminal 113 amino acids of the Escherichia coli P-protein suggests that Lys39 and Gln88 play critical roles in catalyzing the rearrangement of chorismate to prephenate. Five site-directed mutants at these positions have been constructed in which Lys39 was replaced with Arg, Asn, and Gln, and Gln88 was replaced with Arg and Glu. Although the Gln88Arg plasmid failed to produce detectable cross-reacting proteins in E. coli, the other four plasmids were expressed, and the mutant proteins purified to homogeneity. Their structures were similar to wild type enzyme, as indicated by circular dichroism spectra, with Lys39Gln showing a small deviation. In accordance with predictions, all mutations result in major loss of catalytic activity at pH 7.8. However, activity of the Gln88Glu mutant at pH 4.5 exceeded wild-type EcCM. Implications for the mechanism of mutase catalysis are discussed.

Bacterial Proteins↗

PubMed2004

Characterization of the first described mutation of human red blood cell phosphoglycerate mutase.

In a patient with clinical diagnosis of Hereditary Spherocytosis and partial deficiency (50%) of red blood cell phosphoglycerate mutase (PGAM) activity, we have recently reported [A. Repiso, P. Pérez de la Ossa, X. Avilés, B. Oliva, J. Juncá, R. Oliva, E. Garcia, J.L.L. Vives-Corrons, J. Carreras, F. Climent, Red blood cell phosphoglycerate mutase. Description of the first human BB isoenzyme mutation, Haematologica 88 (2003) (03) ECR07] the first described mutation of type B PGAM subunit that as a dimer constitutes the PGAM (EC 5.4.2.1) isoenzyme present in red blood cells. The mutation is the substitution c.690G>A (p.Met230Ile). In this report, we show that the mutated PGAM possesses an abnormal behaviour on ion-exchange chromatography and is more thermo-labile that the native enzyme. We also confirm that, similar to the PGAM isoenzymes from other sources, the BB-PGAM from human erythrocytes has a ping pong or phosphoenzyme mechanism, and that the mutation does not significantly change the K(m) and K(i) values, and the optimum pH of the enzyme. The increased instability of the mutated enzyme can account for the decreased PGAM activity in patient's red blood cells. However, the implication of a change of the k(cat) produced by the mutation cannot be discarded, since we could not determine the k(cat) value of the mutated PGAM.

Adult↗

PubMed2005

Crystal structure of human B-type phosphoglycerate mutase bound with citrate.

The B-type cofactor-dependent phosphoglycerate mutase (dPGM-B) catalyzes the interconversion of 2-phosphoglycerate and 3-phosphoglycerate in glycolysis and gluconeogenesis pathways using 2,3-bisphosphoglycerate as the cofactor. The crystal structures of human dPGM-B bound with citrate were determined in two crystal forms. These structures reveal a dimerization mode conserved in both of dPGM and BPGM (bisphosphoglycerate mutase), based on which a dPGM/BPGM heterodimer structure is proposed. Structural comparison supports that the conformational changes of residues 13-21 and 98-117 determine PGM/BPGM activity differences. The citrate-binding mode suggests a substrate-binding model, consistent with the structure of Escherichia coli dPGM/vanadate complex. A chloride ion was found in the center of the dimer, providing explanation for the contribution of chloride ion to dPGM activities. Based on the structural information, the possible reasons for the deficient human dPGM mutations found in some patients are also discussed.

Amino Acid Sequence↗

PubMed2004

Purification and characterization of methylmalonyl-CoA mutase from a photosynthetic coccolithophorid alga, Pleurochrysis carterae.

Low activity (about 4 mU/mg protein) of 5'-deoxyadenosylcobalamin-dependent methylmalonyl-CoA mutase (MCM; EC 5.4.99.2) was found in a cell homogenate of a photosynthetic coccolithophorid alga, Pleurochrysis carterae. Most of the enzyme occurred as the apo-enzyme, which was labile during purification. The holo-enzyme, which was converted from the apo-enzyme by incubation with 10 microM 5'-deoxyadenosylcobalamin at 4 degrees C in the dark, was purified to homogeneity and partially characterized. An apparent molecular mass for the enzyme of 150+/-5 kDa was calculated by Superdex 200 pg gel filtration. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave a single protein band with an apparent molecular mass of 80+/-5 kDa, indicating that the P. carterae enzyme occurs as a homodimer. Some properties of methylmalonyl-CoA mutase from P. carterae were studied.

Biochemistry↗

PubMed2004

Resveratrol-induced cell growth inhibition and apoptosis is associated with modulation of phosphoglycerate mutase B in human prostate cancer cells: two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry evaluation.

Several studies provide evidence for the anti-carcinogenic activity of resveratrol, a phytoalexin present in grapes and berries, but the precise mechanisms involved in the modulation of prostate carcinogenesis by resveratrol remain to be elucidated. The inhibitory effects induced by resveratrol in human prostate cancer cells impact diverse cellular mechanisms associated with tumor initiation, promotion, and progression. In our earlier studies with prostate cancer cells using cDNA microarray analysis, we indicated the importance of p53-mediated molecular targets of resveratrol. The present study based on two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D-SDS-PAGE) followed by mass spectrometry analysis of human prostate cells that have been treated with resveratrol clearly identifies the role of phosphoglycerate mutase B. For the first time, we report on phosphoglycerate mutase B in the resveratrol-treated prostate cancer cells LNCaP, DU145, and PC-3 at the transcription level. Our observations raise the possibility of its effect on metabolic enzymes in cancer cells without affecting the normal cells.

Antineoplastic Agents, Phytogenic↗

PubMed1988

Comparative effects of two sulfhydryl reagents on the activities of a multifunctional red cell enzyme: bisphosphoglycerate mutase.

The effects of two sulfhydryl reagents on the three activities of bisphosphoglycerate mutase have been compared. Under N-ethylmaleimide treatment all the activities were inhibited except for 60% of the non-stimulated phosphatase. With iodoacetamide the mutase and the stimulated-phosphatase activities were completely inhibited whereas the non-stimulated phosphatase and 60% of the synthase activities were unaffected. 2,3-bisphosphoglycerate protected all the activities of the enzyme against inactivation by the two sulfhydryl reagents whereas 3-phosphoglycerate protected them only against iodoacetamide. 2-phosphoglycolate had an identical effect to that of 3-phosphoglycerate except for its effect on the non-stimulated phosphatase activity, which was slightly enhanced under N-ethylmaleimide treatment.

2,3-Diphosphoglycerate↗

PubMed2003

Unexpected catalytic site variation in phosphoprotein phosphatase homologues of cofactor-dependent phosphoglycerate mutase.

The cofactor-dependent phosphoglycerate mutase (dPGM) superfamily contains, besides mutases, a variety of phosphatases, both broadly and narrowly substrate-specific. Distant dPGM homologues, conspicuously abundant in microbial genomes, represent a challenge for functional annotation based on sequence comparison alone. Here we carry out sequence analysis and molecular modelling of two families of bacterial dPGM homologues, one the SixA phosphoprotein phosphatases, the other containing various proteins of no known molecular function. The models show how SixA proteins have adapted to phosphoprotein substrate and suggest that the second family may also encode phosphoprotein phosphatases. Unexpected variation in catalytic and substrate-binding residues is observed in the models.

Amino Acid Sequence↗