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)

Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. The structural complexity of pectin requires the combined action of several pectinases for its efficient breakdown. Three types of pectinases have so far been identified in E. chrysanthemi: two pectin methyl esterases (PemA, PemB), a polygalacturonase (PehX), and eight pectate lyases (PelA, PelB, PelC, PelD, PelE, PelL, PelZ, PelX). We report in this paper the analysis of a novel enzyme, the pectin acetyl esterase encoded by the paeY gene. No bacterial form of pectin acetyl esterases has been described previously, while plant tissues and some pectinolytic fungi were found to produce similar enzymes. The paeY gene is present in a cluster of five pectinase-encoding genes, pelA-pelE-pelD-paeY-pemA. The paeY open reading frame is 1650 bases long and encodes a 551-residue precursor protein of 60704Da, including a 25-amino-acid signal peptide. PaeY shares one region of homology with a rhamnogalacturonan acetyl esterase of Aspergillus aculeatus. To characterize the enzyme, the paeY gene was overexpressed and its protein product was purified. PaeY releases acetate from sugar-beet pectin and from various synthetic substrates. Moreover, the enzyme was shown to act in synergy with other pectinases. The de-esterification rate by PaeY increased after previous demethylation of the pectins by PemA and after depolymerization of the pectin by pectate lyases. In addition, the degradation of sugar-beet pectin by pectate lyases is favoured after the removal of methyl and acetyl groups by PemA and PaeY, respectively. The paeY gene was first identified on the basis of its regulation, which shares several characteristics with that of other pectinases. Analysis of the paeY transcription, using gene fusions, revealed that it is induced by pectic catabolic products and is affected by growth phase, oxygen limitation and catabolite repression. Regulation of paeY expression appears to be dependent on the KdgR repressor, which controls all the steps of pectin catabolism, and on the catabolite regulatory protein (CRP), the global activator of sugar catabolism. The contiguous pelD, paeY and pemA genes are transcribed as an operon from a promoter proximal to pelD which allows the regulation by KdgR and CRP. However, transcription can be interrupted at the intra-operon Rho-independent terminator situated between pelD and paeY. The paeY mutant inoculated into Saintpaulia plants was less invasive than the wild-type E. chrysanthemi strain 3937, demonstrating the important role of PaeY in the soft-rot disease.
Mol Microbiol 1997 Jun
PMID:Identification of a bacterial pectin acetyl esterase in Erwinia chrysanthemi 3937. 921 76

Following the previous isolation of CLPG1, a gene encoding an endopolygalacturonase (endoPG) secreted into the culture filtrate of Colletotrichum lindemuthianum, we have isolated and sequenced an additional endoPG gene, CLPG2. This gene is present as a single copy in the genome of the fungus. At the amino acid level, CLPG2 shows 61% identity to CLPG1 and between 37 to 59% identity to other fungal endoPGs. RNA blot analyses of endoPG gene expression were followed with specific probes during in vitro culture of the fungus. When conidia were used to inoculate a synthetic medium containing pectin as sole carbon source, only CLPG1 was found to be expressed after 3 days of culture. However, transferring the mycelium grown on glucose for 4 days to a pectin-containing medium allowed the detection of CLPG1 and CLPG2 transcripts as early as 12 h after transfer on this substrate. Expression of CLPG2 was transient while that of CLPG1 was more prolonged. Immunocytological localization of endoPG in C. lindemuthianum-infected bean tissues with antibodies against CLPG1 confirmed that the protein is produced in planta and is associated with extensive degradation of the host cell wall. Detection of endoPG transcripts by reverse transcription-polymerase chain reaction revealed that CLPG1, but not CLPG2, is expressed at the beginning of the necrotrophic stage of infection. These results show that the two endoPG genes are differentially expressed and that CLPG1 encodes the major secreted endoPG both during saprophytic growth and during plant infection.
Mol Plant Microbe Interact 1997 Aug
PMID:Endopolygalacturonase genes from Colletotrichum lindemuthianum: cloning of CLPG2 and comparison of its expression to that of CLPG1 during saprophytic and parasitic growth of the fungus. 924 38

Phytopathogenic strains of Burkholderia cepacia (synonym Pseudomonas cepacia) produce endopolygalacturonase, whereas strains of clinical and soil origin do not. Growth of a phytopathogenic strain (ATCC25416) at elevated temperatures resulted in nonpectolytic derivatives that were either cured of a resident plasmid or contained a plasmid of reduced mass. The resident 200-kb plasmid (pPEC320) in strain ATCC25416 was tagged with Tn5-Mob. The pPEC320::Tn5-Mob (pPEC321) plasmid was mobilized in B. cepacia strains of soil and clinical origin. Transconjugants containing pPEC321 expressed the endopolygalacturonase and showed differential activity on plant tissue. No evidence for self-transfer of pPEC320 or the tagged derivative was observed. A 285-kb cloned fragment from pPEC320 containing the plasmid-borne pehA gene was sequenced and compared to the pehA gene from Erwinia carotovora subsp. carotovora and Ralstonia solanacearum and the polygalacturonase sequence from Lycopersicon esculentum.
Mol Plant Microbe Interact 1997 Sep
PMID:Mobilization, cloning, and sequence determination of a plasmid-encoded polygalacturonase from a phytopathogenic Burkholderia (Pseudomonas) cepacia. 930 58

The pgip-1 gene of Phaseolus vulgaris, encoding a polygalacturonase-inhibiting protein (PGIP), PGIP-1 (P. Toubart, A. Desiderio, G. Salvi, F. Cervone, L. Daroda, G. De Lorenzo, C. Bergmann, A. G. Darvill, and P. Albersheim, Plant J. 2:367-373, 1992), was expressed under control of the cauliflower mosaic virus 35S promoter in tomato plants via Agrobacterium tumefaciens-mediated transformation. Transgenic tomato plants with different expression levels of PGIP-1 were used in infection experiments with the pathogenic fungi Fusarium oxysporum f. sp. lycopersici, Botrytis cinerea, and Alternaria solani. No evident enhanced resistance, compared with the resistance of untransformed plants, was observed. The pgip-1 gene was also transiently expressed in Nicotiana benthamiana with potato virus X (PVX) as a vector. PGIP-1 purified from transgenic tomatoes and PGIP-1 in crude protein extracts of PVX-infected N. benthamiana plants were tested with several fungal polygalacturonases (PGs). PGIP-1 from both plant sources exhibited a specificity different from that of PGIP purified from P. vulgaris (bulk bean PGIP). Notably, PGIP-1 was unable to interact with a homogeneous PG from Fusarium moniliforme, as determined by surface plasmon resonance analysis, while the bulk bean PGIP interacted with and inhibited this enzyme. Moreover, PGIP-1 expressed in tomato and N. benthamiana had only a limited capacity to inhibit crude PG preparations from F. oxysporum f. sp. lycopersici, B. cinerea, and A. solani. Differential affinity chromatography was used to separate PGIP proteins present in P. vulgaris extracts. A PGIP-A with specificity similar to that of PGIP-1 was separated from a PGIP-B able to interact with both Aspergillus niger and F. moniliforme PGs. Our data show that PGIPs with different specificities are expressed in P. vulgaris and that the high-level expression of one member (pgip-1) of the PGIP gene family in transgenic plants is not sufficient to confer general, enhanced resistance to fungi.
Mol Plant Microbe Interact 1997 Sep
PMID:Polygalacturonase-inhibiting proteins (PGIPs) with different specificities are expressed in Phaseolus vulgaris. 930 59

Plant calcium can modulate a particular plant-pathogen interaction and have a decisive role in disease development. Enhanced resistance to the phytopathogenic enterobacterium Erwinia carotovora, the causal agent of bacterial soft rot disease, is observed in high-calcium plants. One of the main virulence determinants of E. carotovora, the PehA endopolygalacturonase, is specifically required in the early stages of the infection. Production of PehA was found to be dependent on the calcium concentration in the bacterial environment. An increase in extracellular calcium to mM concentrations repressed pehA gene expression without reducing or even enhancing expression of other extracellular enzyme-encoding genes of this pathogen. An increase in plant calcium levels could be correlated to enhanced resistance to E. carotovora infection and to an inhibition of in planta production of PehA. Ectopic expression of pehA from a calcium-insensitive promoter allowed E. carotovora to overcome this calcium-induced resistance. The results imply that plant calcium can constitute an important signal molecule in plant-pathogen interaction, which acts by modulating the expression of virulence genes of the pathogen.
Mol Microbiol 1997 Sep
PMID:Control of virulence gene expression by plant calcium in the phytopathogen Erwinia carotovora. 936 9

We previously identified a locus that regulates production of polygalacturonase (PG), an extracellular plant cell wall-degrading enzyme important in bacterial wilt of plants caused by Ralstonia (Pseudomonas) solanacearum. The DNA sequence of this locus, called pehSR, was determined and two consecutive open reading frames (ORFs) of 1,905 and 1,680 bp were identified. The amino acid sequences predicted to be encoded by these ORFs are similar to those of regulators of pilin synthesis in Pseudomonas aeruginosa and Myxococcus xanthus and to a regulator of flagellin synthesis and adhesion in P. aeruginosa, as well as to other two-component regulators of the NtrB/C subfamily. pehSR mutants produced negligible levels of endo-PG activity, while exo-PG activity was reduced by 50%. Northern (RNA) blot analysis showed that PehSR regulates endo-PG expression at the transcriptional level. pehSR mutants grew normally in culture and in planta but were dramatically reduced in virulence; this loss of virulence was substantially greater than that observed for endo-PG structural gene mutants, suggesting that pehSR regulates additional factors important in virulence. Although pehSR mutants were essentially nonmotile, like the wild-type strain, multiple copies of pehSR conferred motility on the bacterium. Reporter gene studies indicated that pehSR expression increased when bacteria grew in plant tissue, and that the pehSR locus was itself negatively regulated by the global virulence gene regulator PhcA.
Mol Plant Microbe Interact 1997 Dec
PMID:A regulatory locus, pehSR, controls polygalacturonase production and other virulence functions in Ralstonia solanacearum. 939 Apr 20

pg1 encoding the major in vitro extracellular endopolygalacturonase of the tomato vascular wilt pathogen Fusarium oxysporum f. sp. lycopersici was cloned and sequenced. The deduced mature protein had a calculated molecular mass of 35.5 kDa and a pI of 6.2, and showed significant similarity with other fungal endoPGs. pg1 mRNA was induced in vitro by citrus pectin, tomato vascular tissue, 0.1% D-galacturonic acid, and polygalacturonic acid, and repressed by 1% D-galacturonic acid and 1% glucose. Reverse transcription-polymerase chain reaction revealed pg1 expression in roots and lower stems of tomato plants infected by F. oxysporum f. sp. lycopersici. Three naturally occurring F. oxysporum f. sp. melonis isolates deficient in PG1 were transformed with the cloned gene. The PG1 enzyme secreted by the transformants had the same molecular mass, pI, and glycosylation pattern as those of the donor isolate. Polygalacturonase activity in cultures of transformants grown in vitro on citrus pectin and on melon plants, but not on glucose, increased 10- to 20-fold, compared with the PG1-deficient wild-type isolate, whereas mycelial dry weight increased two- to three-fold. Transformants exhibited the same degree of virulence toward susceptible muskmelon cultivars as the wild-type isolate and were avirulent on a resistant cultivar.
Mol Plant Microbe Interact 1998 Feb
PMID:Cloning, expression, and role in pathogenicity of pg1 encoding the major extracellular endopolygalacturonase of the vascular wilt pathogen Fusarium oxysporum. 945 Mar 33

Solution conformation of polygalacturonase from Aspergillus carbonarius was determined by spectroscopy. UV absorption, second derivative, near-UV CD, fluorescence emission spectra and fluorescence quenching measurements suggest that the tryptophan fluorophores are in a hydrophobic environment. Of the nine tryptophan residues, only one is exposed to the solvent. In the near UV region the enzyme exhibits very weak CD bands, the far UV CD spectrum has a minimum at 218 nm; the enzyme is rich in parallel beta structure. Modification of solvent exposed tryptophan by N-bromosuccinimide resulted in the complete loss of enzyme activity. The enzyme is very sensitive towards urea induced unfolding, with complete loss of activity at 3 M urea concentration.
Biochem Mol Biol Int 1998 Jan
PMID:Conformation of polygalacturonase-II from Aspergillus carbonarius--a spectroscopic study. 950 50

In vitro culture of VFNT Cherry tomato sepals (calyx) at 16-21 degrees C results in developmental changes that are similar to those that occur in fruit tissue [10]. Sepals become swollen, red, and succulent, produce ethylene, and have increased levels of polygalacturonase RNA. They also produce many flavor volatiles characteristic of ripe tomato fruit and undergo similar changes in sugar content [11]. We examined the expression of the tomato AGAMOUS gene, TAG1, in ripening, in vitro sepal cultures and other tissues from the plant and found that TAG1 RNA accumulates to higher levels than expected from data from other plants. Contrary to reports on the absence of AGAMOUS in sepals, TAG1 RNA levels in green sepals from greenhouse-grown plants is detectable, its concentration increasing with in vitro ripening to levels that were even higher than in red, ripe fruit. Sepals of fruit on transgenic tomato plants that expressed TAG1 ectopically were induced by low temperature to ripen in vivo, producing lycopene and undergoing cell wall softening as is characteristic of pericarpic tissue. We therefore propose that the induction of elevated TAG1 gene expression plays a key role in developmental changes that result in sepal ripening.
Plant Mol Biol 1998 Mar
PMID:Induction of AGAMOUS gene expression plays a key role in ripening of tomato sepals in vitro. 952 6

Pectin methylesterase (PME) is responsible for the demethylation of pectin prior to pectin's degradation by the combined activities of polygalacturonase and pectate lyase. We have differentially screened a maize pollen cDNA library to detect cDNA clones whose genes are specifically expressed in pollen. One group of clones resulting from this screen showed similarity (between 18% and 41% identity) with plant and fungal PMEs. The full-length clone from this group, ZmC5, identifies a small gene family (at least 2 members) when used as a probe on genomic Southern blots. Northern analysis reveals that the ZmC5 transcript is expressed specifically in late pollen development. This tissue-specific gene expression programme is further confirmed in transgenic tobacco plants harbouring ZmC5 promoter/GUS chimeric gene constructs.
Plant Mol Biol 1998 May
PMID:A maize pectin methylesterase-like gene, ZmC5, specifically expressed in pollen. 962 Feb 76


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