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

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

The nucleotide sequence of the Synechococcus sp. PCC7942 glgB gene has been determined. The gene contains a single open reading frame (ORF) of 2322 bp encoding a polypeptide of 774 amino acids (aa) with an Mr of 89,206. Extensive sequence similarity exists between the deduced aa sequence of the Synechococcus sp. glgB gene product and that of the Escherichia coli branching enzyme in the middle portions of the proteins (62% identical aa). In contrast, the N-terminal portions shared little homology. The sequenced region which follows glgB contains an ORF encoding 79 aa of the N terminus of a polypeptide that shares extensive sequence similarity (41% identical aa) with human and rat uroporphyrinogen decarboxylase. This suggests that the region downstream from glgB contains the hemE gene and, therefore, that the organization of genes involved in glycogen biosynthesis in Synechococcus sp. is different from that described for E. coli. A fusion gene was constructed between the 5' end of the Bacillus licheniformis penP gene and the Synechococcus sp. glgB gene. The fusion gene was efficiently expressed in the Gram+ micro-organism Bacillus subtilis and specified a branching enzyme with an optimal temperature for activity similar to the wild-type enzyme.
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PMID:Nucleotide sequence of the Synechococcus sp. PCC7942 branching enzyme gene (glgB): expression in Bacillus subtilis. 214 68

Glycogen branching enzyme was isolated from rabbit liver. The highly purified enzyme shows a monomer molecular weight of 71 000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and apparent molecular weights of 93 000 by sucrose density gradient sedimentation and 52 000 by gel-exclusion chromatography on Sephacryl S-300. No glucosamine, mannosamine, galactosamine, or sialic acid was detected in the protein. An amino acid analysis is reported. The spectrum of branching enzyme is that of a simple polypeptide, with A1%280nm = 24.6. Highly purified branching enzyme consists of several closely related active enzyme forms that can be resolved by isoelectric focusing in polyacrylamide gel. The major species of pI 5.7 is flanked by less abundant forms of pI 5.6 and 5.8. Seemingly identical enzyme forms are observed in crude extracts of rabbit liver, skeletal muscle, brain, and heart, although the absolute and relative concentrations vary among the tissues. Branching enzyme apparently does not exhibit tissue-specific isoenzymes.
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PMID:Isolation and characterization of glycogen branching enzyme from rabbit liver. 622 54

Current evidence suggests that a few global regulatory factors mediate many of the extensive changes in gene expression that occur as Escherichia coli enters the stationary phase. One of the metabolic pathways that is transcriptionally activated in the stationary phase is the pathway for biosynthesis of glycogen. To identify factors that regulate glycogen biosynthesis in trans, a collection of transposon mutants was generated and screened for mutations which independently increase or decrease glycogen levels and the expression of a plasmid-encoded glgC'-lacZ fusion. The glycogen excess mutation TR1-5 was found to be pleiotropic. It led to increased expression of the genes glgC (ADPglucose pyrophosphorylase) and glgB (glycogen branching enzyme), which are representative of two glycogen synthesis operons, and the gluconeogenic gene pckA (phosphoenolpyruvate carboxykinase), and it exhibited effects on cell size and surface (adherence) properties. The mutated gene was designated csrA for carbon storage regulator. Its effect on glycogen biosynthesis was mediated independently of cyclic AMP (cAMP), the cAMP receptor protein, and guanosine 3'-bisphosphate 5'-bisphosphate (ppGpp), which are positive regulators of glgC expression. A plasmid clone of the native csrA gene strongly inhibited glycogen accumulation and affected the ability of cells to utilize certain carbon sources for growth. Nucleotide sequence analysis, complementation experiments, and in vitro expression studies indicated that csrA encodes a 61-amino-acid polypeptide that inhibits glycogen biosynthesis. Computer-assisted data base searches failed to identify genes or proteins that are homologous with csrA or its gene product.
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PMID:Identification and molecular characterization of csrA, a pleiotropic gene from Escherichia coli that affects glycogen biosynthesis, gluconeogenesis, cell size, and surface properties. 839 5

Antibodies were used to probe the degree of association of starch biosynthetic enzymes with starch granules isolated from maize (Zea mays) endosperm. Graded washings of the starch granule, followed by release of polypeptides by gelatinization in 2% sodium dodecyl sulfate, enables distinction between strongly and loosely adherent proteins. Mild aqueous washing of granules resulted in near-complete solubilization of ADP-glucose pyrophosphorylase, indicating that little, if any, ADP-glucose pyrophosphorylase is granule associated. In contrast, all of the waxy protein plus significant levels of starch synthase I and starch branching enzyme II (BEII) remained granule associated. Stringent washings using protease and detergent demonstrated that the waxy protein, more than 85% total endosperm starch synthase I protein, and more than 45% of BEII protein were strongly associated with starch granules. Rates of polypeptide accumulation within starch granules remained constant during endosperm development. Soluble and granule-derived forms of BEII yielded identical peptide maps and overlapping tryptic fragments closely aligned with deduced amino acid sequences from BEII cDNA clones. These observations provide direct evidence that BEII exits as both soluble and granule-associated entities. We conclude that each of the known starch biosynthetic enzymes in maize endosperm exhibits a differential propensity to associate with, or to become irreversibly entrapped within, the starch granule.
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PMID:Physical association of starch biosynthetic enzymes with starch granules of maize endosperm. Granule-associated forms of starch synthase I and starch branching enzyme II. 875 83

In the developing endosperm of monocotyledonous plants, starch granules are synthesized and deposited within the amyloplast. A soluble stromal fraction was isolated from amyloplasts of immature maize (Zea mays L.) endosperm and analyzed for enzyme activities and polypeptide content. Specific activities of starch synthase and starch-branching enzyme (SBE), but not the cytosolic marker alcohol dehydrogenase, were strongly enhanced in soluble amyloplast stromal fractions relative to soluble extracts obtained from homogenized kernels or endosperms. Immunoblot analysis demonstrated that starch synthase I, SBEIIb, and sugary1, the putative starch-debranching enzyme, were each highly enriched in the amyloplast stroma, providing direct evidence for the localization of starch-biosynthetic enzymes within this compartment. Analysis of maize mutants shows the deficiency of the 85-kD SBEIIb polypeptide in the stroma of amylose extender cultivars and that the dull mutant lacks a >220-kD stromal polypeptide. The stromal fraction is distinguished by differential enrichment of a characteristic group of previously undocumented polypeptides. N-terminal sequence analysis revealed that an abundant 81-kD stromal polypeptide is a member of the Hsp70 family of stress-related proteins. Moreover, the 81-kD stromal polypeptide is strongly recognized by antibodies specific for an Hsp70 of the chloroplast stroma. These findings are discussed in light of implications for the correct folding and assembly of soluble, partially soluble, and granule-bound starch-biosynthetic enzymes during import into the amyloplast.
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PMID:Polypeptides of the maize amyloplast stroma. Stromal localization of starch-biosynthetic enzymes and identification of an 81-kilodalton amyloplast stromal heat-shock cognate. 953 63

Screening of a wheat (Triticum aestivum) cDNA library for starch-branching enzyme I (SBEI) genes combined with 5'-rapid amplification of cDNA ends resulted in isolation of a 4,563-bp composite cDNA, Sbe1c. Based on sequence alignment to characterized SBEI cDNA clones isolated from plants, the SBEIc predicted from the cDNA sequence was produced with a transit peptide directing the polypeptide into plastids. Furthermore, the predicted mature form of SBEIc was much larger (152 kD) than previously characterized plant SBEI (80-100 kD) and contained a partial duplication of SBEI sequences. The first SBEI domain showed high amino acid similarity to a 74-kD wheat SBEI-like protein that is inactive as a branching enzyme when expressed in Escherichia coli. The second SBEI domain on SBEIc was identical in sequence to a functional 87-kD SBEI produced in the wheat endosperm. Immunoblot analysis of proteins produced in developing wheat kernels demonstrated that the 152-kD SBEIc was, in contrast to the 87- to 88-kD SBEI, preferentially associated with the starch granules. Proteins similar in size and recognized by wheat SBEI antibodies were also present in Triticum monococcum, Triticum tauschii, and Triticum turgidum subsp. durum.
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PMID:Isolation of a cDNA encoding a granule-bound 152-kilodalton starch-branching enzyme in wheat. 1098 40

A branching enzyme (EC 2.4.1.18) gene was isolated from an extremely thermophilic bacterium, Rhodothermus obamensis. The predicted protein encodes a polypeptide of 621 amino acids with a predicted molecular mass of 72 kDa. The deduced amino acid sequence shares 42-50% similarity to known bacterial branching enzyme sequences. Similar to the Bacillus branching enzymes, the predicted protein has a shorter N-terminal amino acid extension than that of the Escherichia coli branching enzyme. The deduced amino acid sequence does not appear to contain a signal sequence, suggesting that it is an intracellular enzyme. The R. obamensis branching enzyme was successfully expressed both in E. coli and a filamentous fungus, Aspergillus oryzae. The enzyme showed optimum catalytic activity at pH 6.0-6.5 and 65 degrees C. The enzyme was stable after 30 min at 80 degrees C and retained 50% of activity at 80 degrees C after 16 h. Branching activity of the enzyme was higher toward amylose than toward amylopectin. This is the first thermostable branching enzyme isolated from an extreme thermophile.
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PMID:A novel thermostable branching enzyme from an extremely thermophilic bacterial species, Rhodothermus obamensis. 1177 74

Full-length starch branching enzyme II (SBE, EC 2.4.1.18) cDNA from mungbean ( Vigna radiata L. cv. Tainan no. 5), VrsbeII, was cloned, characterized, and expressed as an active enzyme in Escherichia coli . Gene-specific primers first amplified an internal cDNA by reverse transcriptase Polymerase Chain Reaction (RT-PCR), followed by obtaining 5' and 3' fragments by RT-PCR and rapid amplification of cDNA ends (RACE). VrsbeII possesses a complete open reading frame (ORF) of 2571 bp, and the deduced polypeptide includes the common catalytic (beta/alpha)(8)-barrel domain and conserved regions of the alpha-amylase family. Phylogenetic analysis classified VrsbeII into SBE family A. Its partial 3D structure and functional features were predicted. VrsbeII has a shorter N-terminal among SBEs; however, two 6 bp (CCAGTT) direct repeat sequences (DRS) were found. A 24 bp shortened VrsbeII at the 3' end, skipping one DRS, was ligated into pET21b vector and expressed as His(6)-rVrSBEII in E. coli BL21 (DE3) cells. The optimal expression condition for rVrSBEII was evaluated and detected by Western blot with a molecular size of 108 kDa and activity of 6.4 U/mg.
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PMID:Cloning, characterization, and expression of mungbean ( Vigna radiata L.) starch branching enzyme II cDNA in Escherichia coli. 1914 23

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