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At least 19 recordsLinked to original sources
PubMed2005

Transfer of Pectobacterium chrysanthemi (Burkholder et al. 1953) Brenner et al. 1973 and Brenneria paradisiaca to the genus Dickeya gen. nov. as Dickeya chrysanthemi comb. nov. and Dickeya paradisiaca comb. nov. and delineation of four novel species, Dickeya dadantii sp. nov., Dickeya dianthicola sp. nov., Dickeya dieffenbachiae sp. nov. and Dickeya zeae sp. nov.

A collection of 75 strains of Pectobacterium chrysanthemi (including all biovars and pathovars) and the type strains of Brenneria paradisiaca (CFBP 4178(T)) and Pectobacterium cypripedii (CFBP 3613(T)) were studied by DNA-DNA hybridization, numerical taxonomy of 121 phenotypic characteristics, serology and 16S rRNA gene-based phylogenetic analyses. From analysis of 16S rRNA gene sequences, it was deduced that P. chrysanthemi strains and B. paradisiaca CFBP 4178(T) formed a clade distinct from the genera Pectobacterium and Brenneria; therefore, it is proposed to transfer all the strains to a novel genus, Dickeya gen. nov. By DNA-DNA hybridization, the strains of P. chrysanthemi were distributed among six genomic species: genomospecies 1 harbouring 16 strains of biovar 3 and four strains of biovar 8, genomospecies 2 harbouring 16 strains of biovar 3, genomospecies 3 harbouring two strains of biovar 6 and five strains of biovar 5, genomospecies 4 harbouring five strains of biovar 2, genomospecies 5 harbouring six strains of biovar 1, four strains of biovar 7 and five strains of biovar 9 and genomospecies 6 harbouring five strains of biovar 4 and B. paradisiaca CFBP 4178(T). Two strains of biovar 3 remained unclustered. Biochemical criteria, deduced from a numerical taxonomic study of phenotypic characteristics, and serological reactions allowed discrimination of the strains belonging to the six genomic species. Thus, it is proposed that the strains clustered in these six genomic species be assigned to the species Dickeya zeae sp. nov. (type strain CFBP 2052(T)=NCPPB 2538(T)), Dickeya dadantii sp. nov. (type strain CFBP 1269(T)=NCPPB 898(T)), Dickeya chrysanthemi comb. nov. (subdivided into two biovars, bv. chrysanthemi and bv. parthenii), Dickeya dieffenbachiae sp. nov. (type strain CFBP 2051(T)=NCPPB 2976(T)), Dickeya dianthicola sp. nov. (type strain CFBP 1200(T)=NCPPB 453(T)) and Dickeya paradisiaca comb. nov., respectively.

Animals↗
PubMed2006

The phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) is a pathogen of the pea aphid.

Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

Animals↗
PubMed2007

Proteomic analysis of the carbonate insoluble outer membrane fraction of the soft-rot pathogen Dickeya dadantii (syn. Erwinia chrysanthemi) strain 3937.

We present results of the first comprehensive proteomic analysis of the outer membrane of the bacterial phytopathogen Dickeya dadantii strain 3937 and its response to virulence-contributing factors such as host plant extract, acidic stress, and iron starvation. We analyzed the carbonate-insoluble membrane fractions, which are highly enriched for outer membrane proteins, using two-dimensional electrophoresis and identified the proteins by MALDI-TOF MS. Forty unique proteins were identified, some of which were differentially expressed under the above conditions.

Bacterial Outer Membrane Proteins↗
PubMed1992

Ferric iron uptake in Erwinia chrysanthemi mediated by chrysobactin and related catechol-type compounds.

Erwinia chrysanthemi 3937 possesses a saturable, high-affinity transport system for the ferric complex of its native siderophore chrysobactin, [N-alpha-(2,3-dihydroxybenzoyl)-D-lysyl-L-serine]. Uptake of 55Fe-labeled chrysobactin was completely inhibited by respiratory poison or low temperature and was significantly reduced in rich medium. The kinetics of chrysobactin-mediated iron transport were determined to have apparent Km and Vmax values of about 30 nM and of 90 pmol/mg.min, respectively. Isomers of chrysobactin and analogs with progressively shorter side chains mediated ferric iron transport as efficiently as the native siderophore, which indicates that the chrysobactin receptor primarily recognizes the catechol-iron center. Free ligand in excess only moderately reduced the accumulation of 55Fe. Chrysobactin may therefore be regarded as a true siderophore for E. chrysanthemi.

Catechols↗
PubMed1996

Complementation of deletion mutations in a cloned functional cluster of Erwinia chrysanthemi out genes with Erwinia carotovora out homologues reveals OutC and OutD as candidate gatekeepers of species-specific secretion of proteins via the type II pathway.

The type II or Sec-dependent secretion system is used by diverse Gram-negative bacteria for secretion of extracellular proteins. Of the 12-15 proteins involved in secretion, the requirement for many has not been demonstrated and little is known about their functions in the secretion process. The plant pathogens Erwinia chrysanthemi and Erwinia carotovora secrete extra-cellular pectate lyases (Pels) using the type II or Out pathway. However, these two bacteria cannot secrete Pels encoded by heterologously expressed genes from the other species, suggesting the presence of species-specific recognition factors in the Out systems of the two Erwinia species. We previously reported the isolation of a cosmid clone, pCPP2OO6, from E. chrysanthemi EC16, which enables Escherichia coil to secrete heterologously expressed E. chrysanthemi Pels. Sequencing in a region required for secretion revealed the presence of 12 genes, outC-M and outO. We report here the construction of functionally non-polar mutations in each gene in the outC-M operon and outS and outB using a polA(ts) strain of E. coli to facilitate homologous recombination between out genes carrying deletions and their wild-type copies on pCPP2006. By testing for complementation of each deletion with wild-type out genes from E. chrysanthemi EC16 and E. carotovora SCRI193 we have demonstrated that: (i) each out gene is required for secretion of E. chrysanthemi PelE from E. coli with the exception of outH; (ii) each mutation can be complemented by its homologue from E. carotovora, except for outC and outD; (iii) outC and outD from E. carotovora do not confer secretion of Pel1 on the E. chrysanthemi Out system; and (iv) Pel1 secretion can be conferred on the E. chrysanthemi Out system by the presence of outC-M, S and B from E. carotovora. The data suggest that OutC and OutD are gatekeepers of the Out system involved in recognition of Pels targeted for secretion but that OutC and OutD from E. carotovora cannot be successfully assembled into the E. chrysanthemi Out system.

Bacterial Proteins↗
PubMed2003

Rhamnogalacturonate lyase RhiE is secreted by the out system in Erwinia chrysanthemi.

Supernatants of rhamnose-induced Erwinia chrysanthemi strain 3937 cultures contain a principal secreted protein named RhiE. A rhiE mutant has been found among a set of rhamnose-induced MudI1681 lacZ fusions. RhiE is a 62-kDa protein that has rhamnogalacturonate lyase activity on rhamnogalacturonan I (RG-I). It does not require a divalent cation for its activity and has an optimal pH of 6.0. rhiE expression is strongly induced in the presence of rhamnose but is also regulated by PecT and Crp, two regulators of the transcription of pectinolytic enzyme genes. RhiE is secreted through the type II Out secretion pathway. RhiE has no disulfide bond. The absence of RhiE secretion in a dsb mutant indicated that disulfide bond formation is required for the biogenesis of the secretion apparatus. RhiE was searched for in several E. chrysanthemi strains by using antibodies, and it was found to be present in one-third of the strains tested. However, the reduced virulence of the rhiE mutant indicates that degradation of the RG-I region of pectin is important for full virulence of E. chrysanthemi.

Amino Acid Sequence↗
PubMedDate not supplied

Nucleotide sequence of a pectate lyase structural gene, pel1 of Erwinia carotovora subsp. carotovora strain 71 and structural relationship of pel1 with other pel genes of Erwinia species.

Of the various exoproteins secreted by Erwinia carotovora subsp. carotovora strain 71, Pel1 is the major pectate lyase species with tissue macerating activity. Nucleotide sequencing of a 2.2-kb pel1+ DNA segment revealed a 1,122 base pair open reading frame which could encode pre-Pel1 of 374 amino acid residues. A signal peptide of 22 amino acid residues is present within the NH2-terminal region of pre-Pel1. Transcription of pel1 was initiated at the guanine residue 111 base pairs upstream of the start codon. Consensus sequences for the binding of KdgR, a negative regulatory factor known to control some of the E. chrysanthemi pectinases, flank the promoter of pel1. Although pel1 belongs to the pelBC family, it is more closely related to the pel genes of E. carotovora than to the pelBC genes of E. chrysanthemi.

Amino Acid Sequence↗
PubMed1997

The cyclic AMP receptor protein is the main activator of pectinolysis genes in Erwinia chrysanthemi.

The main virulence factors of the phytopathogenic bacterium Erwinia chrysanthemi are pectinases that cleave pectin, a major constituent of the plant cell wall. Although physiological studies suggested that pectinase production in Erwinia species is subjected to catabolite repression, the direct implication of the cyclic AMP receptor protein (CRP) in this regulation has never been demonstrated. To investigate the role of CRP in pectin catabolism, we cloned the E. chrysanthemi crp gene by complementation of an Escherichia coli crp mutation and then constructed E. chrysanthemi crp mutants by reverse genetics. The carbohydrate fermentation phenotype of the E. chrysanthemi crp mutants is similar to that of an E. coli crp mutant. Furthermore, these mutants are unable to grow on pectin or polygalacturonate as the sole carbon source. Analysis of the nucleotide sequence of the E. chrysanthemi crp gene revealed the presence of a 630-bp open reading frame (ORF) that codes for a protein highly similar to the CRP of E. coli. Using a crp::uidA transcriptional fusion, we demonstrated that the E. chrysanthemi CRP represses its own expression, probably via a mechanism similar to that described for the E. coli crp gene. Moreover, in the E. chrysanthemi crp mutants, expression of pectinase genes (pemA, pelB, pelC, pelD, and pelE) and of genes of the intracellular part of the pectin degradation pathway (ogl, kduI, and kdgT), which are important for inducer formation and transport, is dramatically reduced in induced conditions. In contrast, expression of pelA, which encodes a pectate lyase important for E. chrysanthemi pathogenicity, seems to be negatively regulated by CRP. The E. chrysanthemi crp mutants have greatly decreased maceration capacity in potato tubers, chicory leaves, and celery petioles as well as highly diminished virulence on saintpaulia plants. These findings demonstrate that CRP plays a crucial role in expression of the pectinolysis genes and in the pathogenicity of E. chrysanthemi.

Amino Acid Sequence↗
PubMed1994

Identification of the integration host factor genes of Erwinia chrysanthemi 3937.

Two Erwinia chrysanthemi homologues of the himA and himD genes of Escherichia coli which encode the integration host factor (IHF) were cloned, sequenced and compared to their homolog in other enterobacteria (EMBL accession nos X74749 and X74750). Both genes were inactivated by the insertion of an antibiotic resistance cassette, allowing for the isolation of IHF- mutants of E chrysanthemi.

Amino Acid Sequence↗
PubMed1997

The PecM protein is necessary for the DNA-binding capacity of the PecS repressor, one of the regulators of virulence-factor synthesis in Erwinia chrysanthemi.

The pecS regulatory locus is responsible for the down-expression of many virulence genes in Erwinia chrysanthemi. This locus consists of two genes, pecS and pecM, divergently transcribed. Genetic evidence indicates that the PecM protein modulates the regulatory activity of PecS. Purification and characterization of PecS, expressed either from E. coli, from the wild-type E. chrysanthemi strain or from a pecM mutant, showed that the PecS protein produced in these three genetic backgrounds displays the same biochemical properties. Band-shift assay analysis with the three PecS isoforms confirmed the involvement of the PecM protein in modulating the PecS DNA-binding capacity. Moreover, determination of the Kdapp for operator regions of the PecS protein, produced either by the wild-type E. chrysanthemi or by E. coli, reveals similar affinities. Thus, in E. coli, there is likely to be at least one other PecM-like protein able to cross-react with the E. chrysanthemi PecS protein.

Amino Acid Sequence↗
PubMed2001

Role of the nucleoid-associated protein H-NS in the synthesis of virulence factors in the phytopathogenic bacterium Erwinia chrysanthemi.

The ability of the enterobacterium Erwinia chrysanthemi to induce pathogenesis in plant tissue is strongly related to the massive production of plant-cell-wall-degrading enzymes (pectinases, cellulases, and proteases). Additional factors, including flagellar proteins and exopolysaccharides (EPS), also are required for the efficient colonization of plants. Production of these virulence factors, particularly pectate lyases, the main virulence determinant, is tightly regulated by environmental conditions. The possible involvement of the protein H-NS in this process was investigated. The E. chrysanthemi hns gene was cloned by complementation of an Escherichia coli hns mutation. Its nucleotide sequence contains a 405-bp open reading frame that codes for a protein with 85% identity to the E. coli H-NS protein. An E. chrysanthemi hns mutant was constructed by reverse genetics. This mutant displays a reduced growth rate and motility but an increased EPS synthesis and sensitivity toward high osmolarity. Furthermore, pectate lyase production is dramatically reduced in this mutant. The hns mutation acts on at least two conditions affecting pectate lyase synthesis: induction of pectate lyase synthesis at low temperatures (25 degrees C) is no longer observed in the hns mutant and induction of pectate lyase production occurs in the late stationary growth phase in the hns background, instead of in the late exponential growth phase as it does in the parental strain. Moreover, the E. chrysanthemi hns mutant displays reduced virulence on plants. Taken together, these data suggest that H-NS plays a crucial role in the expression of the virulence genes and in the pathogenicity of E. chrysanthemi.

Bacterial Proteins↗
PubMed1993

Mutagenesis of cellulase EGZ for studying the general protein secretory pathway in Erwinia chrysanthemi.

Extracellular secretion of endoglucanase Z (EGZ) from Erwinia chrysanthemi is mediated by the so-called Out general secretion pathway and, presumably, involves recognition of EGZ-carried structural information by one or more of the Out proteins. Investigating the relationships between structure and secretability of EGZ was the purpose of the present work. EGZ is made of two independent domains, located at the N- and C-proximal sides, separated by a Ser/Thr-rich region, which are responsible for catalysis and cellulose-binding, respectively. The existence of a secretion region ('targeting signal') was investigated by studying the secretability of modified EGZ derivatives. These resulted from deletion or peptide insertion and were designed by using the domain organization cited above as a guide. Catalytic and/or cellulose-binding tests showed that all proteins exhibited at least a functional EGZ domain while immunoblot analyses confirmed that neither the insertions nor the deletions led to grossly misfolded proteins. In contrast, all of the proteins lost their secretability in E. chrysanthemi. This suggested that at least two secretion motifs existed, one lying within each functional domain. The role of the Ser/Thr-rich linker region was subsequently tested. Accordingly, two proteins containing a linker region whose length was increased by the addition of 8 and 18 additional residues and one protein lacking the linker region were studied. All three exhibited endoglucanase activity and cellulose-binding ability, confirming the independence of the domains within the context of EGZ/polysaccharide interaction. In contrast, none was secreted by E. chrysanthemi.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2000

Characterization of a tonB mutation in Erwinia chrysanthemi 3937: TonB(Ech) is a member of the enterobacterial TonB family.

The pectinolytic enterobacterium Erwinia chrysanthemi 3937 causes a systemic disease in its natural host, the African violet (Saintpaulia: ionantha). It produces two structurally unrelated siderophores, chrysobactin and achromobactin. Chrysobactin makes a large contribution to invasive growth of the bacterium in its host. Insertion mutants of a chrysobactin-defective strain were constructed and screened on the universal CAS-agar medium used for siderophore detection. A set of mutants affected in the production of achromobactin were identified. This paper describes a mutant affected in the transport of all the ferrisiderophores used by the bacterium as iron sources. Molecular analysis revealed that the insertion mutation disrupts the tonB gene. The predicted Er. chrysanthemi TonB protein has a molecular mass of 27600 Da and shares 20-58% identity with the TonB proteins from 20 other bacterial species. The pathogenicity of the tonB mutant was assessed by inoculation of African violets. The impairment in the spread of symptoms was similar in the tonB mutant to that in chrysobactin-defective mutants. However, the pectinolytic activity, the major pathogenicity determinant in Er. chrysanthemi, appeared to be stimulated twofold in the tonB mutant.

Bacterial Proteins↗