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At least 919 records · Page 51Linked to original sources
PubMed2000

Radial distribution pattern of pectin methylesterases across the cambial region of hybrid aspen at activity and dormancy.

Biochemical microanalysis combined with tangential cryosectioning was used to visualize the distribution of pectin methylesterases (PMEs) across the cambial region in active and dormant hybrid aspen (Populus tremula L. x Populus tremuloides Michx). These novel techniques allowed us to relate activity and isoforms of PMEs to specific tissues and developmental stages of the stem to get more information on the physiological function of PMEs in cambial growth. Isoelectrofocusing analysis revealed numerous isoforms that were differentially distributed according to the tissue-type and to the cambial stage. A neutral isoform was found to be distributed ubiquitously across the stem of both active and dormant trees, which suggests that it is a housekeeping isoform involved in the maintenance of the cell wall integrity throughout the stem. In addition, two distinct isoforms having different isoelectric points were found to be related to the differentiation of cambial derivatives. A basic isoform appears to be a physiological marker of the dormant stage involved in the cessation of meristematic radial growth, whereas an acidic isoform is functionally related to the immediate expansion of the cambial daughter cells that occurs bilaterally on each side of the cambium at the active stage.

Carboxylic Ester Hydrolases↗
PubMed1969

Pectin esterase in relation to leaf abscission in coleus and phaseolus.

Pectin esterase (PE) activities in abscission zones, other portions of leaves, and adjacent stem tissues were compared in attached leaves and abscissing petioles (previously debladed) of Coleus blumei Benth. and Phaseolus vulgaris L., cv. Canadian Wonder. Earlier findings of Osborne in bean were confirmed and changes in PE activity in coleus were shown to resemble those in bean in some respects. In both plants PE was lower in the distal portion of abscission zones of abscissing petioles than in that portion of attached leaves but this difference was not as large or as consistently clear-cut in coleus as in bean. The general level of PE activity was an order of magnitude lower and changes associated with abscission were smaller in coleus than in bean. Auxin treatment of debladed petioles of coleus prevented abscission and resulted in small increases in PE activity in abscission zones and most of the other regions sampled. The largest increase was observed in the stem tissue adjacent to the attached leaf opposite the debladed, auxin treated one.The activity of coleus PE was highest in the pH range from 7.3 to 7.6. The pH of distal tissue from abscission zones of abscissing petioles was 5.8. This was 0.7 pH units lower than that of proximal tissue from the same zones.PE from both coleus and bean appears to be denatured by freezing and/or thawing.

Journal Article↗
PubMed1987

Inhibitory Effects of a Pectin-Enriched Tomato Cell Wall Fraction on Agrobacterium tumefaciens Binding and Tumor Formation.

A pectin-enriched soluble cell wall fraction (CWF) prepared from suspension cultured tomato cells inhibits binding of Agrobacterium tumefaciens to these cells. It was hypothesized that the CWF contains the plant surface binding site for A. tumefaciens (NT Neff, AN Binns 1985 Plant Physiol 77: 35-42). Experiments described here demonstrate that tomato CWF inhibited tumor formation on potato slices and Agrobacterium binding to intact tomato cells in a dose-dependent fashion. Boiling the fraction reduced both its binding and tumor inhibitory activities. Tumor inhibitory activity was titrated out by increased concentrations of bacterial inocula with no inhibition apparent at 1 x 10(8) bacteria per milliliter. These results indicate that a tomato CWF is enriched for a putative A. tumefaciens binding site which may also be involved in tumor formation in potato.

Journal Article↗
PubMed1991

Cell Surface Interactions between Bean Leaf Cells and Colletotrichum lindemuthianum: Cytochemical Aspects of Pectin Breakdown and Fungal Endopolygalacturonase Accumulation.

After a brief period of biotrophic growth, the anthracnose fungus Colletotrichum lindemuthianum (Sacc. et Mgn.) Bri et Cav. develops extensively in bean leaf cells, causing severe wall alterations and death of the host protoplast. Aplysia gonad lectin, a polygalacturonic acid-binding agglutinin, was complexed to gold and used to study the extent of pectin breakdown during the necrotrophic phase of the infection process. In view of its specific binding properties for the endopolygalacturonase produced by C. lindemuthianum, a polygalacturonase-inhibiting protein isolated from bean cell walls was successfully tagged with gold particles and used for localizing the sites of enzyme accumulation in infected host tissues. The basal level of endopolygalacturonase produced by C. lindemuthianum grown in culture was found to increase severalfold when the fungus developed in host plant tissues. The enzyme was able to diffuse freely in the host cell wall, causing drastic degradation of the pectic material of primary walls and middle lamella matrices. The enzymatic alteration of plant cell walls was accompanied by the release of pectic fragments and by the accumulation of pectic molecules at specific sites, such as intercellular spaces and aggregated cytoplasm of infected host cells. The occurrence of pectic molecules at those sites where fungal growth is likely to be restricted is discussed in relation to their origin and their implication in the plant's defense system.

Journal Article↗
PubMed1991

Molecular cloning of tomato pectin methylesterase gene and its expression in rutgers, ripening inhibitor, nonripening, and never ripe tomato fruits.

We have purified pectin methylesterase (PME; EC 3.1.11) from mature green (MG) tomato (Lycopersicon esculentum Mill. cv Rutgers) pericarp to an apparent homogeneity, raised antibodies to the purified protein, and isolated a PME cDNA clone from a lambdagtll expression library constructed from MG pericarp poly(A)(+) RNA. Based on DNA sequencing, the PME cDNA clone isolated in the present study is different from that cloned earlier from cv Ailsa Craig (J Ray et al. [1989] Eur J Biochem 174:119-124). PME antibodies and the cDNA clone are used to determine changes in PME gene expression in developing fruits from normally ripening cv Rutgers and ripening-impaired mutants ripening inhibitor (rin), nonripening (nor), and never ripe (Nr). In Rutgers, PME mRNA is first detected in 15-day-old fruit, reaches a steady-state maximum between 30-day-old fruit and MG stage, and declines thereafter. PME activity is first detectable at day 10 and gradually increases until the turning stage. The increase in PME activity parallels an increase in PME protein; however, the levels of PME protein continue to increase beyond the turning stage while PME activity begins to decline. Patterns of PME gene expression in nor and Nr fruits are similar to the normally ripening cv Rutgers. However, the rin mutation has a considerable effect on PME gene expression in tomato fruits. PME RNA is not detectable in rin fruits older than 45 days and PME activity and protein begin showing a decline at the same time. Even though PME activity levels comparable to 25-day-old fruit were found in root tissue of normal plants, PME protein and mRNA are not detected in vegetative tissues using PME antibodies and cDNA as probes. Our data suggest that PME expression in tomato pericarp is highly regulated during fruit development and that mRNA synthesis and stability, protein stability, and delayed protein synthesis influence the level of PME activity in developing fruits.

Journal Article↗
PubMed2005

VANGUARD1 encodes a pectin methylesterase that enhances pollen tube growth in the Arabidopsis style and transmitting tract.

In flowering plants, penetration of the pollen tube through stigma, style, and transmitting tract is essential for delivery of sperm nuclei to the egg cells embedded deeply within female tissues. Despite its importance in plant reproduction, little is known about the underlying molecular mechanisms that regulate the navigation of the pollen tube through the stigma, style, and transmitting tract. Here, we report the identification and characterization of an Arabidopsis thaliana gene, VANGUARD1 (VGD1) that encodes a pectin methylesterase (PME)-homologous protein of 595 amino acids and is required for enhancing the growth of pollen tubes in the style and transmitting tract tissues. VGD1 was expressed specifically in pollen grain and the pollen tube. The VGD1 protein was distributed throughout the pollen grain and pollen tube, including the plasma membrane and cell wall. Functional interruption of VGD1 reduced PME activity in the pollen to 82% of the wild type and greatly retarded the growth of the pollen tube in the style and transmitting tract, resulting in a significant reduction of male fertility. In addition, the vgd1 pollen tubes were unstable and burst more frequently when germinated and grown on in vitro culture medium, compared with wild-type pollen tubes. Our study suggests that the VGD1 product is required for growth of the pollen tube, possibly via modifying the cell wall and enhancing the interaction of the pollen tube with the female style and transmitting tract tissues.

Amino Acid Sequence↗
PubMed1996

Crystallization and preliminary X-ray analysis of pectin lyase A from Aspergillus niger.

The major secreted pectin lyase (E.C. 4.2.2.10) from Aspergillus niger, strain 4M-147, has been purified and crystallized by the hanging-drop method using polyethylene glycol as precipitant. The crystals belong to the space group P2(1)2(1)2(1) with cell dimensions a = 45.2, b = 83.2, c = 93.1 A (1 A = 0.1 nm) and a single molecule in the asymmetric unit. The crystals diffract to at least 2.0 A resolution and are suitable for structure determination.

Journal Article↗
PubMed1994

Nucleotide sequence, organization and expression of rdgA and rdgB genes that regulate pectin lyase production in the plant pathogenic bacterium Erwinia carotovora subsp. carotovora in response to DNA-damaging agents.

In most soft-rotting Erwinia spp., including E. carotovora subsp. carotovora strain 71 (Ecc71), production of the plant cell wall degrading enzyme pectin lyase (Pnl) is activated by DNA-damaging agents such as mitomycin C (MC). Induction of Pnl production in Ecc71 requires a functional recA gene and the rdg locus. DNA sequencing and RNA analyses revealed that the rdg locus contains two regulatory genes, rdgA and rdgB, in separate transcriptional units. There is high homology between RdgA and repressors of lambdoid phages, specially phi 80. RdgB, however, has significant homology with transcriptional activators of Mu phage. Both RdgA and RdgB are also predicted to possess helix-turn-helix motifs. By replacing the rdgB promoter with the IPTG-inducible tac promoter, we have determined that rdgB by itself can activate Pnl production in Escherichia coli. However, deletion analysis of rdg+ DNA indicated that, when driven by their native promoters, functions of both rdgA and rdgB are required for the induction of pnlA expression by MC treatment. While rdgB transcription occurs only after MC treatment, a substantial level of rdgA mRNA is detected in the absence of MC treatment. Moreover, upon induction with MC, a new rdgA mRNA species, initiated from a different start site, is produced at a high level. Thus, the two closely linked rdgA and rdgB genes, required for the regulation of Pnl production, are expressed differently in Ecc71.

Amino Acid Sequence↗
PubMedDate not supplied

Possible association of glaucoma with pectinate ligament dysplasia and narrowing of the iridocorneal angle in Shiba Inu dogs in Japan.

The purpose of the study was to describe the shape of the pectinate ligament (PL) and to estimate the width of the iridocorneal angle (ICA) in glaucomatous and non-glaucomatous eye of Shiba Inu dogs in Japan. One hundred fourteen Shiba Inu dogs were presented to the Veterinary Medical Center at the University of Tokyo between June 1998 and June 2003. Among these, 46 dogs had glaucoma; the remaining 68 dogs were presented for routine vaccinations or heartworm testing and were used as a control population. Complete ophthalmic examination and gonioscopy were performed in all the dogs. PL and ICA were evaluated by gonioscopy and goniophotographs. Of the 46 dogs with glaucoma, 17 (37%) were affected bilaterally, and 29 (63%) were affected unilaterally. Of the 29 dogs with unilateral glaucoma, the ICA of the normotensive eye was slightly narrow in 2 eyes (7%), narrow in 12 eyes (41%), and closed in 15 eyes (52%). Among the normotensive control group, the ICA was open in 13 dogs (19%), slightly narrow in 29 (43%), narrow in 22 (32%), and closed in 4 (6%). In dogs with narrow and slightly narrow ICAs, the PLs were thickened, and in some cases, formed a solid sheet. The majority of dogs with glaucoma had changes in both ICA and PL. A narrow or slightly narrow ICA was also detected in the majority of normotensive control dogs. This study suggests that ICA narrowing and PL thickening is a common abnormality in Shiba Inu dogs in Japan and may predispose those dogs to glaucoma.

Animals↗
PubMed1985

recA is required in the induction of pectin lyase and carotovoricin in Erwinia carotovora subsp. carotovora.

Pectin lyase (PNL) and the bacteriocin carotovoricin (CTV) were induced in Erwinia carotovora subsp. carotovora 71 by the DNA-damaging agents mitomycin C, nalidixic acid, and UV light. To determine whether the recA product was involved in the expression of these damage-inducible phenotypes, we cloned the E. carotovora subsp. carotovora recA+ gene, inactivated it by Tn5 insertion, and constructed an E. carotovora subsp. carotovora recA::Tn5 strain by gene replacement via homologous recombination. The RecA- strain was more sensitive to methyl methanesulfonate, nitroquinoline oxide, and UV light than its RecA+ parent. The recA mutation did not affect the production of pectate lyase, polygalacturonase, cellulase, and protease or the ability to cause soft rot of potato tubers. With this mutant, unlike with the RecA+ parent strain, PNL and CTV were not induced by mitomycin C or detected in potato tuber tissue. The RecA+ phenotype, including the inducibility of PNL and CTV, could, however, be restored in the mutant in trans by the recA+ gene from either E. carotovora subsp. carotovora or Escherichia coli. We conclude that, in E. carotovora subsp. carotovora, the recA product is required in the induction of PNL and CTV.

Bacteriocins↗
PubMed1989

Regulation and role in pathogenicity of Erwinia chrysanthemi 3937 pectin methylesterase.

The gene pem, encoding the pectin methylesterase (PME) of Erwinia chrysanthemi 3937, was cloned and mutagenized by mini-Mu transposable elements. A second gene, pecY, which could act as a negative regulator of PME was found 5' to the pem gene. A PME-E. chrysanthemi derivative inoculate onto Saintpaulia plants was shown to be clearly noninvasive, demonstrating the important role of this enzyme in soft rot disease.

Carboxylic Ester Hydrolases↗
PubMed1990

Molecular cloning and characterization of an Erwinia carotovora subsp. carotovora pectin lyase gene that responds to DNA-damaging agents.

recA-mediated production of pectin lyase (PNL) and the bacteriocin carotovoricin occurs in Erwinia carotovora subsp. carotovora 71 when this organism is subjected to agents that damage or inhibit the synthesis of DNA. The structural gene pnlA was isolated from a strain 71 cosmid gene library following mobilization of the cosmids into a moderate PNL producer, strain 193. The cosmid complemented pnl::Tn5 but not ctv::Tn5 mutations. A constitutive level of PNL activity was detected in RecA+ and RecA- Escherichia coli strains carrying the pnlA+ gene on the high-copy-number plasmid pBluescript SK-. Mappings of Mu dI1734 (Km lac'ZYA) insertions in pnlA and unidirectional deletion analyses allowed localization of the gene to approximately 1.4 kilobases of DNA. A typical pnlA-lacZ transcriptional fusion was inducible in a RecA+ but not a RecA- derivative of strain 71. In contrast, the pnlA-lacZ fusion was not inducible in a RecA+ E. coli strain. DNA sequences homologous to pnlA were detected in E. carotovora subsp. carotovora and E. carotovora subsp. atroseptica strains and in one of four Erwinia rhapontici strains but not in Erwinia chrysanthemi.

Chromosome Mapping↗
PubMed1991

Nucleotide sequence and molecular characterization of pnlA, the structural gene for damage-inducible pectin lyase of Erwinia carotovora subsp. carotovora 71.

In a previous study, pnlA (the DNA damage-inducible structural gene for pectin lyase) of Erwinia carotovora subsp. carotovora 71 was localized to a 1.4-kb DNA segment within a 3.4-kb EcoRI fragment (J. L. McEvoy, H. Murata, and A. K. Chatterjee, J. Bacteriol. 172:3284-3289, 1990). We present here DNA sequence data for a 2.2-kb region revealing an open reading frame of 870 bases, corresponding to a protein (Pnl) of an approximate molecular mass of 32,100 Da and an isoelectric point of 9.92. Although initiation of translation is presumed to occur at the ATG codon, direct protein sequencing revealed alanine as the N-terminal amino acid, probably as a consequence of posttranslational removal of the initiating amino acid. The sequence of the first 20 amino acid residues of Pnl, purified from E. carotovora subsp. carotovora 71, agreed completely with the predicted amino acid sequence of the N-terminal segment. This finding also indicated that Pnl is not subject to processing by a signal peptidase. The transcriptional start site of pnlA was determined to reside 80 bp upstream of the translational start site. Deletion analysis revealed that 218 bp of DNA upstream of the transcriptional start site is sufficient for induction of pnlA by mitomycin C. Within 600 bp upstream of the translational start site, no sequences resembling a LexA binding site (SOS box) or a cyclic AMP receptor protein binding site were found. However, palindromic sequences were detected at -187 and -86 bp relative to the translational start site, and these could be potential sites for the binding of a regulatory protein(s). Comparison of the deduced amino acid sequence for PnlA with that of a Pnl from Aspergillus niger and with those of various pectate lyases of Erwinia species revealed a low degree of homology dispersed throughout the length of the proteins.

Amino Acid Sequence↗
PubMed1992

Genetic evidence for an activator required for induction of pectin lyase in Erwinia carotovora subsp. carotovora by DNA-damaging agents.

In Erwinia carotovora subsp. carotovora 71, the induction of pectin lyase (Pnl), the bacteriocin carotovoricin (Ctv), and cellular lysis (Lss) requires a RecA function. We obtained mutants wherein a pleiotropic defect, i.e., the lack of induction with mitomycin C, is not restored by the recA+ DNA. From a genomic library of strain 71, a cosmid (pAKC280) that restored induction of Pnl, Ctv, and Lss by mitomycin C was isolated. The activator function, designated Rdg for regulator of damage-inducible genes, was localized by subcloning and insertional mutagenesis to a 2.6-kb region within a 6.7-kb EcoRI fragment. An rdg-lacZ operon fusion was inducible by mitomycin C in RecA+ but not RecA- derivatives of E. carotovora subsp. carotovora 71 and Escherichia coli. A RecA+ E. coli strain carrying only a PnlA+ plasmid was not inducible for Pnl production; however, when both a PnlA+ plasmid and a Rdg+ plasmid were present, the transcription of pnlA and the production of the enzyme were activated by mitomycin C. The size of the pnlA transcript produced in E. coli was identical to that of the transcript produced by E. carotovora subsp. carotovora 71, suggesting that the same promoter and termination sequences were being utilized in these bacteria.

Bacteriocins↗
PubMed1998

Role of pectinate muscle bundles in the generation and maintenance of intra-atrial reentry: potential implications for the mechanism of conversion between atrial fibrillation and atrial flutter.

To determine the role of pectinate muscle (PM) bundles in the formation of intra-atrial reentry, 10 isolated canine right atrial tissues were perfused with Tyrode's solution containing 1 to 2.5 micromol/L acetylcholine (ACh). The endocardium was mapped using 477 bipolar electrodes with 1.6-mm resolution. Reentry was induced by a premature stimulus (S2). Computer simulation studies were used to investigate the importance of regional myocardial thickness in reentry formation. A total of 40 episodes of reentry were induced; 28 episodes were stationary, and the remaining 12 were nonstationary. The stationary reentry was induced either immediately after the S2 stimuli (n=9) or after an initial period of irregular activations that lasted 1460+/-1077 ms (n= 19). Of 28 episodes, 20 were initiated by conduction block along large PM ridges, leading to wave break and the initiation of reentry. The reentrant wave fronts remained stationary and rotated around these ridges as anchoring sites. During the transition from the initial irregular activations to stationary reentry, the electrogram morphology converted from "fibrillation-like" to "flutter-like" activity. In 8 episodes, initially stationary reentry converted to irregular activations because of interference with outside wave fronts (n=5) or spontaneous separation of waves from the ridges (n=3). Compared with stationary reentry, nonstationary reentry always occurred over an area without large PMs, and the mean life span was much shorter (102+/-151 versus 3.8+/-1.1 rotations, P<0.001). Computer simulation studies showed that a critical ridge thickness is needed for reentry to anchor, thereby converting fibrillation to flutter. We conclude that PM ridge forms an area where wave break occurs, allowing the initiation of reentry. It also provides a natural anchor to the reentrant wave front, lengthening the life span of reentry. The attachment and detachment of the reentrant wave front to and from the ridge determine "flutter-like" or "fibrillation-like" activity.

Animals↗
PubMed1994

Analysis of promoter region of the pectin lyase gene from Erwinia carotovora Er.

A pectin lyase defective mutant was constructed from Erwinia carotovora Er by transposon Tn5 insertion mutagenesis to analyze the promoter region of the pnl gene, which had been cloned. The promoter of pnl is between -140 and -74 upstream of the structural gene of pnl and appears not to be regulated by Lex A.

Amino Acid Sequence↗
PubMed1999

Pectin methylesterase gene (pmeA) from Aspergillus oryzae KBN616: its sequence analysis and overexpression, and characterization of the gene product.

A gene (pmeA) encoding pectin methylesterase was isolated from a shoyu koji mold, Aspergillus oryzae KBN616, and characterized. The structural gene comprised 1,370 bp with six introns. The PMEA protein consisted of 331 amino acids with a putative signal peptide of 17 amino acids. The deduced amino acid sequence was very similar to those of Aspergillus niger PMEA and Aspergillus aculeatus PME1. The pmeA gene was efficiently expressed under control of the A. oryzae TEF1 gene promoter for purification and characterization of the ezymatic properties. PMEA had a molecular mass of 38.5 kDa, a pH optimum of 5.0, and a temperature optimum of 55 degrees C.

Amino Acid Sequence↗