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:3.2.1.15 (pectinase)
2,440 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have purified and isolated cDNAs encoding the beta subunit of tomato fruit polygalacturonase isoenzyme 1 (PG1), a cell wall protein that associates with, and apparently regulates, the catalytic PG2 polypeptides. Expression of the beta subunit is fruit specific and temporally separated from the expression of PG2 during fruit development. The 37- to 39-kD beta subunit is encoded as a 69-kD precursor protein containing a signal sequence and two propeptide domains. The mature protein is composed almost entirely of the novel 14-amino acid motif FTNYGxxGNGGxxx in which many of the phenylalanine residues are post-translationally modified. The unique structural features of the motif suggest an important role in the function of the protein and hence in the activity of PG1. The beta subunit may represent a class of bifunctional plant proteins that interact both with structural components of the cell wall and catalytic proteins to localize and/or regulate metabolic activities within the cell wall.
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PMID:The beta subunit of tomato fruit polygalacturonase isoenzyme 1: isolation, characterization, and identification of unique structural features. 139 11

The endopolygalacturonase (EC 3.2.1.15) enzyme produced in vitro by Sclerotinia sclerotiorum were found to consist of numerous isoforms covering a broad pI range. Two of the isoforms, labelled PG2 and PG3, were purified using gel-filtration chromatography, isoelectric focusing and anion-exchange chromatography. The pIs of PG2 and PG3 were, respectively, 4.8 and 4.9. Their molecular weights were similar. Both enzymes hydrolysed 0.9% of the bonds in reaching a 50% reduction in viscosity. However, their enzymic parameters were different. Their amino acid compositions differed only in the aspartic acid-asparagine content. The N-terminal sequences differed at the fourth amino acid only. PG2 and PG3 exhibited a high level of glycosylation compared to a similar enzyme isolated from Aspergillus niger. Antibody raised against PG3 was shown to crossreact with PG2, but not with the enzyme purified from Aspergillus niger.
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PMID:Purification and characterization of two endopolygalacturonases from Sclerotinia sclerotiorum. 199 Nov 45

The developmental changes that accompany tomato fruit ripening include increased solubilization and depolymerization of pectins due to the action of polygalacturonase (PG). Two PG isoenzymes can be extracted from ripe fruit: PG2, which is a single catalytic PG polypeptide, and PG1, which is composed of PG2 tightly associated with a second noncatalytic protein, the beta subunit. Previous studies have correlated ripening-associated increases in pectin solubilization and depolymerization with the presence of extractable PG1 activity, prior to the appearance of PG2, suggesting a functional role for the beta subunit and PG1 in pectin metabolism. To assess the function of the beta subunit, we produced and characterized transgenic tomatoes constitutively expressing a beta subunit antisense gene. Fruit from antisense lines had greatly reduced levels of beta subunit mRNA and protein and accumulated < 1% of their total extractable PG activity in ripe fruit as PG1, as compared with 25% for wild type. Inhibition of beta subunit expression resulted in significantly elevated levels of EDTA-soluble polyuronides at all stages of fruit ripening and a significantly higher degree of depolymerization at later ripening stages. Decreased beta subunit protein and extractable PG1 enzyme activity and increased pectin solubility and depolymerization all cosegregated with the beta subunit antisense transgene in T2 progeny. These results indicate (1) that PG2 is responsible for pectin solubilization and depolymerization in vivo and (2) that the beta subunit protein is not required for PG2 activity in vivo but (3) does play a significant role in regulating pectin metabolism in wild-type fruit by limiting the extent of pectin solubilization and depolymerization that can occur during ripening. Whether this occurs by direct interaction of the beta subunit with PG2 or indirectly by interaction of the beta subunit with the pectic substrate remains to be determined.
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PMID:Reduction of tomato polygalacturonase beta subunit expression affects pectin solubilization and degradation during fruit ripening. 782 95

An exo-polygalacturonase (EC 3.2.1.15) was purified to apparent homogeneity from cultures of Fusarium oxysporum f.sp. lycopersici on synthetic medium supplemented with citrus pectin, using preparative isoelectric focusing. The enzyme, denominated PG2, had an apparent M(r) of 74000 Da upon SDS-PAGE. The pI of the main PG2 isoform was 4.5, and pH and temperature optima were 5.0 and 55 degrees C, respectively. PG2 hydrolyzed polygalacturonic acid in an exo-manner, as demonstrated by anaysis of degradation products. The enzyme was N-glycosylated. The N-terminal amino acid sequence, L-A-F-N-V-P-S-K-P-P, has no identify to other known polygalacturonases.
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PMID:Purification and characterization of an exo-polygalacturonase from the tomato vascular wilt pathogen Fusarium oxysporum f.sp. lycopersici. 896 70

Three multiple forms of polygalacturonase (PG) in ripe and two in unripe banana (Musa acuminata) fruits were separated by DEAE-cellulose and further purified using Sephadex G-150 chromatography. The multiple forms can be differentiated from each other on the basis of their properties. PG1 and PG3 were identified as endo-PG and PG2 as exo-PG on the basis of decrease in viscosity, increase in reducing sugar and the reaction product. PG2 and PG3 increased with the ripening of fruits. PG1, PG2 and PG3 exhibited optimum activity at pH 3.3, 3.7 and 4.3, respectively. Complete loss of PG2 and PG1 activities occurred at 60 and 70 degrees, but PG3 retained 60 and 50% activity respectively. The three forms showed a different response towards divalent metal ions. Ca2+ activated PG1 activity only. Teepol 0.1%, inhibited PG1 activity by 25%, but PG2 and PG3 activities were completely inhibited. CTAB, 0.1%, had no effect on PG1 and PG2 activities, but inhibited PG3 activity by 40%. 2-ME stimulated PG2 and PG3 activities but had no effect on PG1 activity. Gel filtration through Sephacryl indicated M(r) of 23,200, 58,000 and 130,000, respectively, for PG1, PG2 and PG3. The substrate saturation curve for PG1 and PG2 were Michaelian, while PG3 showed biphasic curve. The Km values of PG1 and PG2 were 0.22% and 0.14%, respectively.
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PMID:Multiple forms of polygalacturonase from banana fruits. 963 63

The cell wall acts as the first line of defense during pathogen invasion. Polygalacturonases (PGs) are a class of cell-wall-modifying enzymes with precise temporal and organ-specific expression. A 350-bp fragment with high homology to PGs was identified by differential display (DD) analysis of soybean cyst nematode (SCN) race 3 resistant PI 437654 and susceptible cultivar Essex. The fragment was strongly expressed in Essex, 2 days after inoculation (DAI). Complete coding sequences of two PG cDNAs, PG1 and PG2, were isolated by 3' and 5' rapid amplification of cDNA ends polymerase chain reaction (RACE PCR). PI 437654 and Essex had identical PG1 and PG2 sequences. A transversion from A to C created a PstI restriction site in the PG2 cDNA that was used to distinguish the two PG cDNAs by cleaved amplified polymorphic sequence (CAPS) analysis. A cDNA encoding a polygalacturonase-inhibitor protein (PGIP) that is 89% identical to the Phaseolus vulgaris PGIP was isolated from soybean roots by reverse transcription (RT)-PCR. Steady-state levels of PG and PGIP were investigated by RNA gel blot analysis in roots 1 to 5 DAI and in hypocotyls and leaves. Differences in the constitutive levels of PG mRNAs were observed in roots of different soybean genotypes. Steady-state levels of PG mRNAs were enhanced during compatible interactions with SCN and reduced in incompatible interactions and in mechanically wounded roots. Enhanced PGIP transcription was observed in response to mechanical wounding in both PI 437654 and Essex, but only in compatible interactions with SCN, suggesting uncoupling of PGIP functions in developmental and stress cues. Constitutive expression in incompatible interactions shows PGIP is not a factor in SCN resistance. Thus, the up-regulation of endogenous PG transcription in soybean roots early after SCN infection could facilitate successful parasitism by SCN.
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PMID:Polygalacturonase and polygalacturonase inhibitor protein: gene isolation and transcription in Glycine max-Heterodera glycines interactions. 1035

The filamentous fungus Penicillium olsonii secretes several polygalacturonases (PGs) with molecular masses of about 47 kDa. These enzymes consist of several basic and acidic isoforms, with dominant activities at pI 4.5 and pI 7.9. Two polygalacturonase genes, pg1 and pg2, have been cloned. The corresponding enzymes, PG1 and PG2, consist of 370 and 380 amino acids, respectively, and show significant similarities to endo-polygalacturonases from other filamentous fungi. Targeted disruption of pg1 resulted in the elimination of all basic PG isoforms. In contrast, disruption of pg2 reduced, but did not eliminate the acidic PG activities. The PGs of P. olsonii must therefore be encoded by a gene family of at least three genes. Induction studies with various carbon sources revealed that the acidic and basic isoforms are differentially regulated. Pectin is the best inducer of the acidic PG isoforms. The basic isoforms, however, are best induced by monosaccharides like glucose, alpha-L-rhamnose and alpha-L-arabinose.
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PMID:Cloning and targeted disruption of two polygalacturonase genes in Penicillium olsonii. 1080 87

Sclerotinia sclerotiorum, a plant pathogenic ascomycete, contains a neutral endopolygalacturonase (endoPG) subfamily of genes that was previously isolated. We report here that pg2, a member of this subfamily, is early and strongly expressed during the first steps of pathogenesis of sunflower cotyledons. The corresponding protein, PG2, was produced in the heterologous Kluyveromyces lactis system and purified. Characterization of the recombinant enzyme revealed a narrow pH activity curve with an optimal pH of 4.5. Hydrolysis of polygalacturonic acid by PG2 resulted in the accumulation of oligomers ranging from 2- to 9-mer. This degradation profile indicates a random attack on the polymer and demonstrates an endo-mode of action. These results provide evidence that pg2 contributes to the infection process during the early phase of host colonization.
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PMID:Characterization of PG2, an early endoPG produced by Sclerotinia sclerotiorum, expressed in yeast. 1216 44

The first polygalacturonase from a plant, tomato fruit PG2, has been crystallized and data have been collected to a resolution of 1.87 A. The autoindexing program strongly favors one of the primitive orthorhombic cells. A plausible molecular-replacement solution for two molecules in the asymmetric unit has been found for data assigned to space group P2(1)2(1)2(1). Although the numerical criteria and the electron-density maps are reasonable for this solution, manually adjusted models do not refine to an R factor below 0.48. Visual inspection of hkl Bragg planes does not reveal a breakdown in mm symmetry. Nevertheless, the correct space group has been determined to be P2(1), with similar unit-cell parameters, a beta angle of 90.04 degrees and four molecules in the asymmetric unit. The R(sym) of 0.053 for data processed in P2(1)2(1)2(1) is very similar to the R(sym) of 0.047 for the same data processed in P2(1). Comparisons of the intermediate results using the P2(1)2(1)2(1) and P2(1) data sets are provided and the subtle indications of an initial erroneous space-group assignment are discussed.
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PMID:Resolving the space-group ambiguity of crystals of tomato fruit polygalacturonase. 1464 66

Tomato polygalacturonase (PG) was extracted from ripe tomatoes and purified by cation exchange and gel filtration chromatography. Cation exchange chromatography yielded two peaks with PG activity: the first peak was identified as PG2 (the heat labile form) and the second one as PG1 (the heat stable form). Both PG2 and PG1 presented a molar mass of 42 kDa when analyzed by SDS-PAGE and an isoelectric point >9.3. Thermal inactivation of purified tomato PG2, at pH 4.4, in the temperature range from 53 to 63 degrees C, followed first-order kinetics. Combined pressure-temperature inactivation of tomato PG2 was studied at 5-55 degrees C/100-600MPa. Under all pressure-temperature conditions, PG2 inactivation followed first-order kinetics. Purified tomato PG1, although more thermostable than PG2, showed a pressure stability very similar to that of PG2. These results indicate that high-pressure processing is an efficient alternative to inactivate tomato PG without the need for applying high temperatures.
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PMID:Inactivation kinetics of purified tomato polygalacturonase by thermal and high-pressure processing. 1511 78


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