Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.4.1.18 (branching enzyme)
628 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the yeast Saccharomyces cerevisiae, glycogen serves as a major storage carbohydrate. In a previous study, mutants with altered glycogen metabolism were isolated on the basis of the altered iodine-staining properties of colonies. We found that when glycogen produced by strains carrying the glc-1p (previously called gha1-1) mutation is stained with iodine, the absorption spectrum resembles that of starch rather than that of glycogen, suggesting that this mutation might reduce the level of branching in the glycogen particles. Indeed, glycogen branching activity was undetectable in extracts from a glc3-1p strain but was elevated in strains which expressed GLC3 from a high-copy-number plasmid. These observations suggest that GLC3 encodes the glycogen branching enzyme. In contrast to glc3-1p, the glc3-4 mutation greatly reduces the ability of yeast to accumulate glycogen. These mutations appear to be allelic despite the striking difference in the phenotypes which they produce. The GLC3 clone complemented both glc3-1p and glc3-4. Deletions and transposon insertions in this clone had parallel effects on its ability to complement glc3-1p and glc3-4. Finally, a fragment of the cloned gene was able to direct the repair of both glc3-1p and glc3-4. Disruption of GLC3 yielded the glycogen-deficient phenotype, indicating that glycogen deficiency is the null phenotype. The glc3-1p allele appears to encode a partially functional product, since it is dominant over glc3-4 but recessive to GLC3. These observations suggest that the ability to introduce branches into glycogen greatly increases the ability of the cell to accumulate that polysaccharide. Northern (RNA) blot analysis identified a single mRNA of 2,300 nucleotides that increased in abundance ca. 20-fold as the culture approached stationary phase. It thus appears that the expression of GLC3 is regulated, probably at the level of transcription.
...
PMID:GLC3 and GHA1 of Saccharomyces cerevisiae are allelic and encode the glycogen branching enzyme. 172

The structural gene for the Bacillus stearothermophilus glycogen branching enzyme (glgB) was cloned in Escherichia coli. Nucleotide sequence analysis revealed a 1917 nucleotide open reading frame (ORF) encoding a protein with an Mr of 74787 showing extensive similarity to other bacterial branching enzymes, but with a shorter N-terminal region. A second ORF of 951 nucleotides encoding a 36971 Da protein started upstream of the glgB gene. The N-terminus of the ORF2 gene product had similarity to the Alcaligenes eutrophus czcD gene, which is involved in cobalt-zinc-cadmium resistance. The B. stearothermophilus glgB gene was preceded by a sequence with extensive similarity to promoters recognized by Bacillus subtilis RNA polymerase containing sigma factor H (E - sigma H). The glgB promoter was utilized in B. subtilis exclusively in the stationary phase, and only transcribed at low levels in B. subtilis spoOH, indicating that sigma factor H was essential for the expression of the glgB gene in B. subtilis. In an expression vector, the B. stearothermophilus glgB gene directed the synthesis of a thermostable branching enzyme in E. coli as well as in B. subtilis, with optimal branching activity at 53 degrees C.
...
PMID:Molecular cloning and nucleotide sequence of the glycogen branching enzyme gene (glgB) from Bacillus stearothermophilus and expression in Escherichia coli and Bacillus subtilis. 174 26

We describe 2 unrelated patients with adult polyglucosan body disease (APBD) diagnosed by sural nerve biopsy. Both patients were offspring of consanguineous marriages. They presented clinically with late onset pyramidal tetraparesis, micturition difficulties, peripheral neuropathy, and mild cognitive impairment. Magnetic resonance imaging of the brain revealed extensive white matter abnormalities in both. In search of a possible metabolic defect, we evaluated glycogen metabolism in these patients and their clinically unaffected children. Branching enzyme activity in the patients' polymorphonuclear leukocytes was about 15% of control values, whereas their children displayed values of 50 to 60%, suggesting a possible autosomal recessive mode of transmission. This is the first report of an inherited metabolic defect in patients with adult polyglucosan body disease. We suggest that branching enzyme dysfunction may be implicated in the pathogenesis of some patients with adult polyglucosan body disease.
...
PMID:Hereditary branching enzyme dysfunction in adult polyglucosan body disease: a possible metabolic cause in two patients. 176 91

A 30-year-old woman with clinical features and biochemical findings of muscle phosphofructokinase deficiency was found to have a very low level of alpha-1,4-glucan:alpha-1,4-glucan-6-transglucosylase (branching enzyme, EC 2.4.1.18) activity in muscle. In contrast, branching enzyme activity in the leukocytes was in the range of control values. After sedimentation of the glycogen from muscle homogenates by centrifugation at 105,000 g, branching enzyme activity in muscle of the patient was similar to that of control subjects. This patient illustrates the possibility of falsely diagnosing branching enzyme deficiency when muscle glycogen content is elevated. It is likely that such an artefact may also cause a false positive diagnosis of branching enzyme deficiency in other metabolic diseases associated with glycogen accumulation.
...
PMID:Apparent absence of glycogen branching enzyme activity in phosphofructokinase deficiency. 183 26

A Butyrivibrio fibrisolvens H17c glgB gene, was isolated by direct selection for colonies that produced clearing on starch azure plates. The gene was expressed in Escherichia coli from its own promoter. The glgB gene consisted of an open reading frame of 1,920 bp encoding a protein of 639 amino acids (calculated Mr, 73,875) with 46 to 50% sequence homology with other branching enzymes. A limited region of 12 amino acids showed sequence similarity to amylases and glucanotransferases. The B. fibrisolvens branching enzyme was not able to hydrolyze starch but stimulated phosphorylase alpha-mediated incorporation of glucose into alpha-1,4-glucan polymer 13.4-fold. The branching enzyme was purified to homogeneity by a simple two-step procedure; N-terminal sequence and amino acid composition determinations confirmed the deduced translational start and amino acid sequence of the open reading frame. The enzymatic properties of the purified enzyme were investigated. The enzyme transferred chains of 5 to 10 (optimum, 7) glucose units, using amylose and amylopetin as substrates, to produce a highly branched polymer.
...
PMID:Characterization of the Butyrivibrio fibrisolvens glgB gene, which encodes a glycogen-branching enzyme with starch-clearing activity. 193 80

The interaction of Neurospora crassa branching enzyme (1,4-alpha-D-glucan:1,4-alpha-D-glucan 6-alpha-(1,4-alpha-glucano)-transferase) [EC 2.4.1.18] with substrate glycogen or amylopectin was studied by affinity electrophoresis. By this method, the dissociation constants (K) of the branching enzyme for oyster glycogen (CL-12.2, OCL-6.3) and for potato amylopectin (CL-20, OCL-12.8) were determined to be 13.3 mM and 0.355 mM, respectively. The affinity of the enzyme to the substrate glycogen increased with the increase of outer chain length (OCL) of the substrate. The thermodynamic parameters of the branching reaction were obtained from the changes of K values of the enzyme-substrate complex at various temperatures. The value of heat change (delta H degree) of the branching reaction for amylopectin was -27.7 kcal/deg.mol. The most suitable length of glucan chain for branching was greater than 12 glucose units.
...
PMID:A kinetic study of the interaction between glycogen and Neurospora crassa branching enzyme. 213 55

Glycogen accumulation in Escherichia coli is inversely related to the growth rate and occurs most actively when cells enter the stationary phase. The levels of the three biosynthetic enzymes undergo corresponding changes under these conditions, suggesting that genetic control of enzyme biosynthesis may account for at least part of the regulation (J. Preiss, Annu. Rev. Microbiol. 38:419-458, 1984). We have begun to explore the molecular basis of this control by identifying factors which affect the expression of the glycogen genes and by determining the 5'-flanking regions required to mediate the regulatory effects. The in vitro coupled transcription-translation of two of the biosynthetic genes, glgC (ADPglucose pyrophosphorylase) and glgA (glycogen synthase), was enhanced up to 26- and 10-fold, respectively, by cyclic AMP (cAMP) and cAMP receptor protein (CRP). Guanosine 5'-diphosphate 3'-diphosphate stimulated the expression of these genes 3.6- and 1.8-fold, respectively. The expression of glgB (glycogen branching enzyme) was affected weakly or negligibly by the above-mentioned compounds. Assays which measured the in vitro formation of the first dipeptide of glgC showed that a restriction fragment which contained 0.5 kilobases of DNA upstream from the initiation codon supported cAMP-CRP-activated expression. Sequence-specific binding of cAMP-CRP to a 243-base-pair restriction fragment from the region upstream from glgC was observed by virtue of the altered electrophoretic mobility of the bound DNA. S1 nuclease protection analysis identified 5' termini of four in vivo transcripts within 0.5 kilobases of the glgC coding region. The relative concentrations of transcripts were higher in the early stationary phase than in the exponential phase. Two mutants which overproduced the biosynthesis enzymes accumulated elevated levels of specific transcripts. The 5' termini of three of the transcripts were mapped to a high resolution. Their upstream sequences showed weak similarity to the E. coli consensus promoter. These results suggest complex transcriptional regulation of the glycogen biosynthesis genes involving multiple promoter sites and direct control of gene expression by at least two global regulatory systems.
...
PMID:Genetic regulation of glycogen biosynthesis in Escherichia coli: in vitro effects of cyclic AMP and guanosine 5'-diphosphate 3'-diphosphate and analysis of in vivo transcripts. 246 50

Although type IV glycogen storage disease (Andersen disease; McKusick 23250) is considered to be a rare, autosomally recessive disorder, of the more than 600 patients with glycogenosis identified in our laboratory by enzymatic assays, 6% have been shown to be deficient in the glycogen branching enzyme. Most of the 38 patients with type IV glycogen storage disease who are known to us have succumbed at a very early age, with the exception of one male teenager, an apparently healthy 7-year-old male, and several 5-year-old patients. Fourteen pregnancies at risk for branching enzyme deficiency have been monitored using cultured amniotic fluid cells, and four additional pregnancies have been screened using cultured chorionic villi. Essentially no branching enzyme activity was detectable in eight samples (amniocytes); activities within the control range were found in five samples (three amniocyte and two chorionic villi samples); and five samples appeared to have been derived from carriers. In two of the cases lacking branching enzyme activity, in which the pregnancies were terminated and fibroblasts were successfully cultured from the aborted fetuses, no branching enzyme activity was found. Another fetus, which was predicted by antenatal assay to be affected, was carried to term. Skin fibroblasts from this baby were deficient in branching enzyme. Pregnancies at risk for glycogen storage disease due to the deficiency of branching enzyme can be successfully monitored using either cultured chorionic villi or amniocytes.
...
PMID:Branching enzyme activity of cultured amniocytes and chorionic villi: prenatal testing for type IV glycogen storage disease. 252 70

1. Branching enzymes from rat and rabbit liver, as well as from potato and maize were prepared. They were almost free from contaminating glucan-degrading enzymes. 2. In 'sweet corn' maize, two separate fractions with (alpha 1,4)glucan: (alpha 1,4)glucan alpha 6-glycosyltransferase activities were obtained. One of them synthesized amylopectin, the branched component of starch, in the presence of phosphorylase and Glc1P, while the other fraction synthesized phytoglycogen. Furthermore, in a maize variety which does not accumulate phytoglycogen, only one fraction of branching activity was found, that formed amylopectin under the above-mentioned conditions. 3. Comparative analyses performed with native (alpha 1,4)-(alpha 1,6)glucopolysaccharides, and those synthesized in vitro with the branching enzyme from the same tissue, demonstrated a close similarity between both glucans. 4. It may be concluded that the branching enzyme is responsible for the specific degree of (alpha 1,6) branch linkages found in the native polysaccharide.
...
PMID:The degree of branching in (alpha 1,4)-(alpha 1,6)-linked glucopolysaccharides is dependent on intrinsic properties of the branching enzymes. 295 76

The nucleotide sequences of the Escherichia coli genome between the glycogen biosynthetic genes glgB and glgC, and 1170 bp of DNA which follows glgA have been determined. The region between glgB and glgC contains an open reading frame (ORF) of 1521 bp which we call glgX. This ORF is capable of coding for an Mr 56,684 protein. The deduced amino acid (aa) sequence for the putative product shows significant similarity to the E. coli glycogen branching enzyme, and to several different glucan hydrolases and transferases. The regions of sequence similarity include residues which have been reported to be involved in substrate binding and catalysis by taka-amylase. This suggests that the proposed product may catalyze hydrolysis or glycosyl-transferase reactions. The cloned region which follows glgA contains an incomplete ORF (1149 bp), glgY, which appears to encode 383 aa of the N terminus of glycogen phosphorylase, based upon sequence similarity with the enzyme from rabbit muscle (47% identical aa residues) and with maltodextrin phosphorylase from E. coli (37% identical aa residues). Results suggest that neither ORF is required for glycogen biosynthesis. The localization of glycogen biosynthetic and degradative genes together in a cluster may facilitate the regulation of these systems in vivo.
...
PMID:Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes. 297 49


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---