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Results for “Polygalacturonase”

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PubMed1999

A leucine-rich repeat protein of carrot that exhibits antifreeze activity.

A gene encoding an antifreeze protein (AFP) was isolated from carrot (Daucus carota) using sequence information derived from the purified protein. The carrot AFP is highly similar to the polygalacturonase inhibitor protein (PGIP) family of apoplastic plant leucine-rich repeat (LRR) proteins. Expression of the AFP gene is rapidly induced by low temperatures. Furthermore, expression of the AFP gene in transgenic Arabidopsis thaliana plants leads to an accumulation of antifreeze activity. Our findings suggest that a new type of plant antifreeze protein has recently evolved from PGIPs.

Amino Acid Sequence↗
PubMed2001

The study of a monocotyledon abscission zone using microscopic, chemical, enzymatic and solid state 13C CP/MAS NMR analyses.

We have investigated distinguishing features in cells of the abscission zone of a monocotyledon fruit, the oil palm Elaeis guineensis. The cell walls of the abscission zone and the subtending mesocarp and pedicel have been analysed by light and transmission electron microscopy, by chemical methods and by solid state 13C CP/MAS NMR spectroscopy. Results show that these abscission zone cells have specific characteristics which include high levels of unmethylated pectin in the walls and an inducible (x35) polygalacturonase enzyme expression. Together these findings help to explain the localised precision of cell separation events.

Enzyme Induction↗
PubMed2001

Pectic polysaccharide rhamnogalacturonan II is covalently linked to homogalacturonan.

A borate-containing pectin was solubilized from sugar beet (Beta vulgaris L. ) cell walls by treatment with 0.5 M imidazole, pH 7. The molecular weight of the pectin was reduced when the borate ester was hydrolyzed by treatment with 1 N HCl. Treatment of the acid-treated pectin with boric acid in the presence of Pb(2+) gave a product whose molecular weight distribution was similar to the imidazole-soluble pectin. The imidazole-soluble pectin was saponified and then digested with endo- and exo-polygalacturonases. These treatments shifted the boron peak at the high molecular weight region to the low molecular weight (10 kDa), which corresponds to rhamnogalacturonan II-borate ester cross-linked dimer (dRG-II-B). The treatment also generated rhamnogalacturonan I (RG-I), dRG-II-B, monomeric rhamnogalacturonan II and galacturonic acid. These results show that imidazole solubilizes a high molecular weight borate-containing pectic complex composed of homogalacturonan-rhamnogalacturonan II and RG-I. Our data suggest that borate esters formed between rhamnogalacturonan II molecules cross-link the macromolecular pectin.

Borates↗
PubMed2001

Failed expression of an endo-beta-1,4-glucanhydrolase (cellulase) in a non-abscinding mutant of Lupinus angustifolius cv Danja.

Cellulase expressions in a normal shedding wild-type and a non-abscinding single gene mutant of Lupinus angustifolius have been studied during ethylene treatments of leaf abscission zone explants. Of the range of different glycohydrolases investigated only the abscission cell-specific beta-1,4-glucanhydrolase (cellulase) was not produced in the non-abscinding mutant. An endo-polygalacturonase was induced equally in both wild-type and mutant and other glycohydrolases were equally up-regulated. The abscission cell-specific cellulase induced at shedding of wild-type is antigenically similar to the Phaseolus vulgaris induced leaf abscission pI 9.5 cellulase but with a higher molecular mass (50 kD compared with 48 kD) and like the bean abscission-specific cellulase that of lupin is not glycosylated. Causes of the loss of function of cellulase expression in the non-shedding mutant are discussed.

Cellulase↗
PubMed2003

Pectate lyase activity during ripening of banana fruit.

Pectate lyase (PEL) activity was demonstrated in ripe banana fruits on supplementing the homogenizing medium with cysteine and Triton X-100. The enzyme was characterized on the basis of alkaline pH optimum, elimination of the activity by EDTA and activation by Ca(2+). PEL activity was not detected in preclimacteric banana fruits. PEL activity increased progressively from early climacteric and reached maximum level at climacteric peak and declined in post climacteric and over ripened fruits. Replacing pectate with pectin in PEL assay manifested enzyme activity even in preclimacteric fruits. In contrast to PEL, polygalacturonase activity progressively increased during fruit ripening even in postclimacteric fruits.

Calcium↗
PubMed2003

Optimising growth conditions for the pectinolytic activity of Kluyveromyces wickerhamii by using response surface methodology.

This present study was undertaken to find optimum conditions of pH, temperature and, period of incubation for the pectinolytic activity of Kluyveromyces wickerhamii isolated from rotting fruits and to assess the effect of these factors by use of response surface methodology (RSM). A central composite rotatable design was used as an experimental design for the analysis of the allocation of treatment combinations. A second order polynomial regression model was fitted and was found adequate, with an R(2) of 0.94469 (P<0.001). The effects of temperature and pH were the most significant factors in influencing enzyme production. Estimated optimum conditions were as follows: pH 5.0, temperature, 32 degrees C and an incubation period of 91 h. Pectinesterase (PE), pectin lyase (PL), and cellulase activities were not detected. Pectinase production was partially constitutive. Pectin was degraded by the isolated strain of K. wickerhamii in the current study, and the pectinolytic activity is referred to as polygalacturonase (PG) activity. Crude enzyme extract was thermostable at various temperatures and, stimulated by the presence of Ca(2+) ions but inhibited by other ions like Mg(2+), Zn(2+), Co(2+), Mn(2+) and Na(+).

Bacteriological Techniques↗
PubMed2003

Detection of Penicillium expansum by polymerase chain reaction.

Penicillium expansum is a major causative agent of postharvest decay in a variety of fruits, including apples, peaches, nectarines, and cherries. It causes significant economic losses to the fruit industry and is also of potential public health significance, since it produces patulin, a mycotoxin known to cause harmful effects in animals. Rapid and specific detection of P. expansum is important for ensuring microbiological quality and safety of fruits and fruit juices. The traditional methods for identification of P. expansum are time-consuming and labor-intensive. In this study, we report a polymerase chain reaction utilizing primers based on the polygalacturonase gene of P. expansum. The PCR amplified a 404-bp DNA product from all the P. expansum isolates tested, but not in other common foodborne Penicillium species and Escherichia coli. Experiments to determine the sensitivity of the PCR indicated that it can detect the DNA equivalent from as low as 25 spores of P. expansum. The PCR could potentially be used as a rapid tool for screening fruits for the presence of P. expansum.

Beverages↗
PubMed1978

Influence of light on pectic enzymes in root exudates of Trifolium alexandrinum inoculated with Rhizobium trifolii.

An in vitro experiment was conduced under bacteriologically controlled conditions to examine the effect of light on the production of pectin methyl esterase (PME) and pectin polygalacturonase (PG) in the root exudates of Trifolium alexandrinum inoculated with an efficient strain of Rhizobium trifolii. The results revealed that PME and PG increased with an increase in the duration of light to which plants were exposed. However, both the enzymes were detected in the root exudates of nonphotosynthesizing plants.

Esterases↗
PubMed1979

The effect of temperature and age of strains of Fusarium oxysporum on its enzymatic activity.

The activities of pectin-methyl-esterase, polygalacturonase, cellulase, amylase, saccharase, and protease of strains of Fusarium oxysporum (Schlecht.) f.sp. pisi (Linford) were studied. The selected strains showed different symptoms and different degrees of pathogenicity on the host plant. The measurements were performed during the growth of strains at constant temperatures and, in another experiment, on the day at different temperatures at which the individual strains were grown. Activities were determined by the plate methods and by the spectrophotometric method. It has been found that enzyme activity of the strains with different degree of pathogenicity show considerable differences in dependence on temperature and growth dynamics.

Amylases↗
PubMed1979

Activity of pectinases, amylases, and saccharase in Pythium spp.

The activity of pectine-lyase, polygalacturonase, pectine-methyl-esterase, amylase, and saccharase in Pythium ultimum, Pythium oligandrum, and Pythium debaryanum was determined. Cultures of fungi were cultivated under different temperatures and pH-values within 24 hours and 15 days. The optimum temperature for production of the mentioned enzymes was found to be 24 degrees C. Furthermore, the influence of pH and age of culture on activity of enzyme was investigated. The same trend was found in all the fungus species examined.

Amylases↗
PubMed2003

Ambient pH controls the expression of endopolygalacturonase genes in the necrotrophic fungus Sclerotinia sclerotiorum.

In the necrotrophic fungus Sclerotinia sclerotiorum, secretion of polygalacturonases (PGs) and decrease of the environmental pH via oxalic acid production are considered as the main pathogenicity determinants. In order to evaluate the relationship between these two aspects of the infection process, we analyzed the expression of the endoPG-encoding genes pg1-3. Transcription of pg1-3 was not carbon regulated but was strictly controlled by pH and highly favored in a narrow range of acidic pH. During plant infection, a pH gradient was established in relation to oxalic acid secretion. Transcripts of pg1-3 were localized to the zone of colonization of healthy tissues while transcripts of genes encoding other lytic enzymes were restricted to the more acidic zones of the infected tissues. Our results show that progressive acidification of the ambient medium by the fungus is a major strategy for the sequential expression of pathogenicity factors.

Ascomycota↗
PubMed2000

A comparison of the pectate lyase genes, pel-1 and pel-2, of Colletotrichum gloeosporioides f.sp. malvae and the relationship between their expression in culture and during necrotrophic infection.

Extracellular pectic lyase and polygalacturonase activities of Colletotrichum gloeosporioides f.sp. malvae were detected in broths containing mallow cell wall extract, pectin or glucose as the carbon source. The initial pH of the broth as well as the carbon source had major influences on pectinase enzyme activities. In the host, only pectic lyase activity was detected, which began at the end of the biotrophic phase and increased in the necrotrophic phase of infection. Two full-length pectate lyase cDNAs, pel-1 and pel-2, were cloned from the fungus. Both genes showed similar patterns of expression when the fungus was grown in mallow cell-wall extract and pectin medium, and the only major difference in expression in culture was that only pel-2 was expressed in glucose broth. Expression of pel-1 and pel-2 was also affected by the initial pH of the medium. Expression of pel-2, but not pel-1, was detected during infection of the host, round-leaved mallow, Malva pusilla. Transcripts of pel-2 were first detectable during the necrotrophic phase of infection approx. 24h after the first detection of pectic lyase enzyme activity. A comparison of expression of pel-1 and pel-2 in culture and in planta with other pectinase genes of C. gloeosporioides f.sp. malvae, as well as with other plant pathogenic fungi, indicates that expression during necrotrophic infection correlates with the ability to be expressed in media containing glucose.

Amino Acid Sequence↗
PubMed2006

A complement fixing polysaccharide from Biophytum petersianum Klotzsch, a medicinal plant from Mali, West Africa.

Biophytum petersianum Klotzsch (syn. Biophytum sensitivum (L.) DC) is a medicinal plant having a traditional use, among others, as a wound healing remedy in Mali and other countries. As a water extract of the aerial parts of the plant is a frequently used preparation, we decided to look for a bioactive polysaccharide in this extract. One of the obtained polysaccharide fractions, BP100 III, isolated from a 100 degrees C water extract from the aerial parts of B. petersianum and having a monosaccharide composition typical for pectic substances, was shown to exhibit potent dose-dependent complement fixating activity. The BP100 III fraction was subjected to degradation by endo-alpha-d-(1-->4)-polygalacturonase, and three fractions were obtained by gel filtration. The highest molecular weight fraction, BP100 III.1, had a more potent activity in the complement test system than the native polymer, while the two lower molecular weight fractions were less active than the native polymer. The major part of BP100 III.1 consists of galacturonic acid and rhamnose, with branches being present on both the rhamnose and galacturonic acid residues. Arabinogalactan type II is also present in the polymer, indicating that BP100 III.1 has a structure typical of the hairy region of pectins. The major part of the two other fractions is a galacturonan, containing a strikingly high number of branch points, some to which xylose is attached. These results indicate that the pectic substance in B. petersianum contains both rhamnogalacturonan and xylogalacturonan regions.

Animals↗
PubMed2002

Hydrolytic activity and ultrastructural changes in fruit skins from two prickly pear (Opuntia sp.) varieties during storage.

The activity of four cell wall hydrolases, pectinmethylesterase (PME), polygalacturonase (PG), cellulase, and beta-galactosidase (beta-Gal), was measured in fruit skins of two prickly pear varieties, Naranjona and Charola, during storage at 18 degrees C and 85-95% relative humidity (RH). In Naranjona (Opuntia ficus indica), of short postharvest life (ca. 2 weeks), PG, cellulase, and beta-Gal increased their activity more than twice, whereas PME activity tended to increase only slightly during storage. In Charola (Opuntia sp.), of long postharvest life (ca. 2 months), only beta-Gal increased its activity (77%), showing a high PG activity from the beginning of storage. Transmission electron microscopy observations showed middle lamella dissolution at the end of storage for both varieties. Naranjona showed a higher cell wall enzymatic activity than Charola, in agreement with their storability differences. Our results suggest that PG and cellulase in Naranjona and PG and beta-Gal in Charola are the main enzymes responsible for cell wall hydrolytic and ultrastructural changes in skins of stored prickly pears.

Carboxylic Ester Hydrolases↗
PubMed2002

Kinetic parameters for the thermal inactivation of quality-related enzymes in carrots and potatoes.

Kinetic parameters for the thermal inactivation of several enzymes in carrot and potato homogenates have been determined. In carrots the most heat-resistant activity was polygalacturonase, followed by peroxidase and pectinmethylesterase. In potatoes peroxidase was the most resistant, followed by pectin methylesterase, polyphenol oxidase, and lipoxygenase. There were several notable similarities between the inactivation kinetics in the two vegetables. In both cases peroxidase activity gave simple first-order inactivation kinetics but yielded a curved Arrhenius plot for the temperature dependence. Pectin methylesterase in both commodities consisted of a labile and a resistant form. The relative amounts of the two forms and the temperature dependences for their inactivation were also similar.

Carboxylic Ester Hydrolases↗
PubMed2003

Elucidation of pectin methylester distributions by capillary electrophoresis.

Evidence is presented that the electrophoretic mobility of the polysaccharide pectin in typical capillary electrophoresis (CE) experiments is determined largely by its chain-averaged charge density, irrespective of how that charge is distributed. This was found to be the case for both high and low calcium sensitive sister fractions separated from a mother sample on the grounds of calcium affinity and for blocky methylester distributions generated by a processive demethylating enzyme. The blockiness of the generated intramolecular methylester distribution was substantiated experimentally, also by CE, by observing the oligomeric digest fragments produced by incubation with endo-polygalacturonase II from Aspergillus niger. The conclusion that the CE migration time is largely invariant to the intramolecular methylester distribution supports the idea that the CE peak shapes can be used to give a useful indication of the intermolecular methylester distribution.

Aspergillus niger↗
PubMed2003

Simultaneous transgenic suppression of LePG and LeExp1 influences rheological properties of juice and concentrates from a processing tomato variety.

Processing tomato lines suppressed in the accumulation of ripening-related polygalacturonase or expansin were generated by introduction of transgenes to silence expression of the LePG and LeExp1 genes, respectively. The rheological properties of juice and juice reconstituted from paste produced from lines suppressed in one of these genes, or in both, were compared with azygous controls. When assayed by measuring Bostwick consistency, paste produced from either suppressed LePG or suppressed LeExp1 lines and diluted to 5 degrees Brix was approximately 18% more viscous than that produced from controls. Simultaneous suppression of LePG and LeExp1 produced a small additional increase in viscosity of 4%. Rheometric flow analysis at 5 or 10 degrees Brix also showed substantial increases in the consistency index due to suppression of either LePG or LeExp1 alone, and a small additional increase when both genes were suppressed in the same transgenic line. Measurements by laser diffraction and [1H]NMR showed that suppression of LePG or LeExp1 accumulation altered the size distribution of insoluble particles and modified their surface properties. The data are consistent with suppression of LePG increasing serum viscosity, and suppression of either LePG or LeExp1 altering the properties of the insoluble particles and improving some aspect of particle-particle or particle-serum interaction, or both. However, relative to that caused by suppression of either gene alone, the additional increase in viscosity caused by simultaneous suppression of LePG and LeExp1 together was slight.

Beverages↗
PubMed2003

Simultaneous transgenic suppression of LePG and LeExp1 influences fruit texture and juice viscosity in a fresh market tomato variety.

Tomatoes are grown for fresh consumption or for processing of the fruit. Some ripening-associated processes of the fruit can either contribute to or degrade attributes associated with both fresh and processing quality. For example, cell wall disassembly is associated with loss of fresh fruit firmness as well as with loss of processed tomato product viscosity. Several enzymes contribute to cell wall polysaccharide disassembly. Polygalacturonase (PG, poly[1,4-alpha-d-galactouronide] glucanohydrolase, EC 3.2.1.15) is among the most abundant polysaccharide hydrolases in ripening tomato fruit and is the major contributor to pectin depolymerization. Expansin (LeExp1) is also abundant in ripening fruit and is proposed to contribute to cell wall disassembly by nonhydrolytic activity, possibly by increasing substrate accessibility to other enzymes. Suppression of either LePG or LeExp1 expression alone results in altered softening and/or shelf life characteristics. To test whether simultaneous suppression of both LePG and LeExp1 expression influences fruit texture in additive or synergistic ways, transgenic Lycopersicon esculentum var. Ailsa Craig lines with reduced expression of either LePG or LeExp1 were crossed. Fruits from the third generation of progeny, homozygous for both transgenic constructs, were analyzed for firmness and other quality traits during ripening on or off the vine. In field-grown transgenic tomato fruit, suppression of LeExp1 or LePG alone did not significantly increase fruit firmness. However, fruits suppressed for both LePG and LeExp1 expression were significantly firmer throughout ripening and were less susceptible to deterioration during long-term storage. Juice prepared from the transgenic tomato fruit with reduced LePG and LeExp1 expression was more viscous than juice prepared from control fruit.

Beverages↗