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Query: UNIPROT:P06889 (Mol)
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The pelE gene of Erwinia chrysanthemi strain EC16 encodes an extracellular pectate lyase protein that is important in virulence on plants. Control of pelE expression is complex, because the gene is regulated by catabolite repression, substrate induction, and growth-phase inhibition. A Tn7-lux reporter gene system was employed to define DNA sequences comprising the pelE promoter. When EC16 cells were grown on medium containing sodium polypectate, pelE transcriptional start sites were observed only at 95 and 96 bases upstream of the translational start site. However, DNA sequences required for pelE expression were also shown by deletion analysis to reside between 196 and 215 base pairs upstream of the translational start site. In addition to these upstream elements, two putative operator sequences that interact with negative regulatory factors occurred downstream of the transcriptional start. Finally, deletion of three bases from a putative catabolite gene activator protein binding site in the pelE promoter eliminated activity. The data demonstrate that the pelE promoter is complex and suggest that it interacts with several regulatory proteins.
Mol Plant Microbe Interact
PMID:Analysis of the pelE promoter in Erwinia chrysanthemi EC16. 131 73

Pseudomonas viridiflava is a soft-rotting pathogen of harvested vegetables that produces an extracellular pectate lyase (PL) responsible for maceration of plant tissue. A pel gene encoding PL was cloned from the genome of strain SJ074 and efficiently expressed in Escherichia coli. After a series of deletion subclonings and analysis by transposon mutagenesis, the pel gene was located in a 1.2-kb PstI-BglII genomic fragment. This fragment appears to contain a promoter at the PstI end required for pel gene expression. The PL produced by pectolytic E. coli clones is identical to those produced by strain SJ074 and by other strains of P. viridiflava in terms of molecular weight (42 kDa) and pI (9.7). A mutant of strain SJ074, designated MEI, which had Tn5 specifically inserted in the pel locus was constructed by site-directed mutagenesis. The MEI mutant produced 70- to 100-fold less PL than the wild type and failed to cause tissue maceration in plants. PL production and soft-rot pathogenicity in MEI and in a Pel- mutant previously isolated from strain SF312 were restored to the wild-type level by complementation in trans with the cloned pel gene. By using the 1.2-kb fragment as a probe, pel homologs were detected in four bacteria that are pathologically unrelated to P. viridiflava. These include three pathovars of P. syringae (pv. lachrymans, pv. phaseolicola, and pv. tabaci) and Xanthomonas campestris pv. malvacearum. No DNA fragments showing homology to pel of P. viridiflava were detected in genomic digests prepared from two strains of soft-rot erwinias.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Plant Microbe Interact
PMID:Cloning and characterization of a pectate lyase gene from the soft-rotting bacterium Pseudomonas viridiflava. 132 18

A genomic clone has been isolated which contains an open reading frame of 1191 bp interrupted by two small introns. The ORF has been sequenced and the transcriptional start determined. The predicted amino acid sequence shows homology to the deduced amino acid sequences of two pollen-specific pectate lyase genes identified in tomato. The genomic clone was isolated using a partial cDNA clone, TP10, which had been isolated from a Nicotiana tabacum pollen cDNA library by means of differential screening. TP10 has been fully sequenced and contains an open reading frame of 792 bp which shows 96% homology to the ORF in the genomic clone. The transcript corresponding to TP10 is maximally expressed late in pollen development, and has not been detected in vegetative tissues.
Plant Mol Biol 1992 Nov
PMID:Isolation and characterization of a tobacco gene with homology to pectate lyase which is specifically expressed during microsporogenesis. 142 Nov 52

The pectate lyase (EC 4.2.2.9) from Bacillus subtilis has been crystallized. Crystals of form 1, grown by the hanging drop method using polyethylene glycol as precipitant, diffract to at least 2.4 A resolution. They belong to the spacegroup P2(1) with a = 132.9 A, b = 41.2 A, c = 156.8 A and beta = 114.9 degrees with probably four molecules in the asymmetric unit. A second crystal form grown from 2-methyl-2,4-pentandiol also belongs to the spacegroup P2(1) with a = 55.0 A, b = 88.1 A, c = 50.2 A and beta = 109.0 degrees. These crystals diffract to at least 2.0 A and have one molecule in the asymmetric unit. Both crystal forms are suitable for the determination of high-resolution structures.
J Mol Biol 1992 Dec 20
PMID:Crystallization and preliminary X-ray studies of the pectate lyase from Bacillus subtilis. 147 89

In vitro gene fusions were constructed between the polygalacturonase-encoding pehA gene of the Erwinia carotovora subsp. carotovora (Ecc) strain SCC3193 and the bla gene of pBR322. The gene fusions obtained (75-2, 75-5 and 75-6) encoded hybrid proteins with the entire signal peptide and 70, 260 or 327 amino acids (aa) of the mature 376 aa PehA protein, respectively, fused to the mature part of the periplasmic beta-lactamase. All three hybrid proteins remained cell-bound in Ecc. High-level expression of the longer fusions 75-5 and 75-6 in Ecc led to reduced growth and viability of the cells. This phenotype was utilized to select for spontaneous extragenic mutations restoring normal cell growth. Two classes of regulatory mutants were obtained by this selection. First, mutants impaired in the production of several exoenzymes, including polygalacturonase, were found. These were phenotypically similar to the previously characterized Exp- mutants. Secondly, mutants specifically impaired in the production of polygalacturonase (designated PehR-), but producing and secreting wild-type levels of pectate lyase and cellulase, were obtained. The PehR- mutations were shown to affect transcriptional activation of the pehA gene. Furthermore, the PehR- as well as PehA- mutants exhibited a reduced virulence phenotype suggesting that polygalacturonase is a virulence factor in Ecc.
Mol Gen Genet 1992 Jul
PMID:Expression of pehA-bla gene fusions in Erwinia carotovora subsp. carotovora and isolation of regulatory mutants affecting polygalacturonase production. 149 88

A recombinant plasmid pIJ3079 contains DNA sequences from Xanthomonas campestris pv campestris involved in coordinate negative regulation of production of the extracellular enzymes protease, endoglucanase, amylase and polygalacturonate lyase, and extracellular polysaccharide (EPS). Wild-type bacteria harbouring pIJ3079 and therefore carrying extra copies of the gene(s) therein showed reduced enzyme and EPS production and reduced aggressiveness to plants. Localised Tn5 mutagenesis of the corresponding region of the genome gave mutants producing higher levels of enzymes and EPS than the wild type, suggesting that the gene(s) may negatively regulate production in the normal cell. Enzyme and EPS production in the mutants was still dependent on previously characterised positive regulatory genes.
Mol Gen Genet 1990 Jun
PMID:Cloning of genes involved in negative regulation of production of extracellular enzymes and polysaccharide of Xanthomonas campestris pathovar campestris. 170 Feb 68

A group of four genes of Erwinia chrysanthemi involved in pectin degradation has been characterized. These four genes form independent transcription units and are regulated by the negative regulatory gene, kdgR. The functions of two of these genes are known: kduD codes for the 2-keto-3-deoxygluconate oxydoreductase and kdul for the 5-keto-4-deoxyuronate isomerase, two enzymes of the pectin degradation pathway. kdgC has 36% homology with pectate lyase genes of the periplasmic family but its product does not seem to have pectinolytic activity. The fourth gene, kdgF, could have a role in the pathogenicity of E. chrysanthemi. A comparison of the regulatory regions of all the genes controlled by kdgR allowed better definition of the KdgR-binding-site consensus.
Mol Microbiol 1991 Sep
PMID:Analysis of an Erwinia chrysanthemi gene cluster involved in pectin degradation. 176 86

A set of cDNAs that are expressed in tomato anthers were isolated. We further characterized two of these cDNAs (LAT56 and LAT59) and their corresponding genomic clones. LAT56 and LAT59 show low levels of steady-state mRNA in immature anthers and maximal levels in mature anthers and pollen. The LAT56 and LAT59 genes are single-copy in the tomato genome, and are linked on chromosome 3, approximately 5 cM apart. Although these cDNAs did not cross-hybridize, their deduced protein sequences (P56 and P59) have 54% amino acid identity. The LAT56 and LAT59 genes each have two introns, but they are located in non-homologous positions. P56 and P59 show significant protein sequence similarity to pectate lyases of plant pathogenic bacteria. The similarity of P56 and P59 to the bacterial pectate lyases is equivalent to the homology described for different pectate lyase sequences of the genus Erwinia. We suggest that the pollen expression of LAT56 and LAT59 might relate to a requirement for pectin degradation during pollen tube growth.
Plant Mol Biol 1990 Jan
PMID:Molecular and genetic characterization of two pollen-expressed genes that have sequence similarity to pectate lyases of the plant pathogen Erwinia. 198 91

Polygalacturonase (Peh) and other pectolytic enzymes play a crucial role in the maceration of vegetables by soft rot Erwinia spp. We have sequenced the peh gene of Erwinia carotovora subsp. carotovora, and identified its product as a precursor of molecular weight 42,639, and a mature protein of molecular weight 42,200. A putative KdgR-binding site was identified in the region 5' to the peh gene. The Peh protein showed significant homology with Peh from tomato. In addition, we have found homologies between pectin methylesterase and pectate lyase from Erwinia and their counterparts in tomato. These homologies are described, and their significance discussed.
Mol Microbiol 1990 Jun
PMID:Sequence of the peh gene of Erwinia carotovora: homology between Erwinia and plant enzymes. 221 11

A pel gene cloned from strain EC153 of Erwinia carotovora encoded a pectate lyase that macerated plant tissue with moderate efficiency. This gene, called pel153, was sequenced and found to possess considerable homology with a pectate lyase gene from Yersinia pseudotuberculosis. The Yersinia protein, however, was truncated at the carboxyl terminal end relative to the Erwinia gene product and had a lower isoelectric point. The Erwinia pel153 gene was overexpressed in cells of Escherichia coli, and a 56-kDa protein was observed on sodium dodecyl sulfate-polyacrylamide gels. This compares with a molecular weight of 61 kDa for the mature, secreted protein as determined from sequencing data. Southern blot analysis disclosed the presence of the pel153 gene in three different strains of E. carotovora, but mutation of the gene in strain EC153 did not affect its ability to soft-rot potato tubers.
Mol Plant Microbe Interact
PMID:Cloning and characterization of a pectate lyase gene from Erwinia carotovora EC153. 252 Jan 59


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