scholarly journals A Two-Component Regulatory System, pehR-pehS, Controls Endopolygalacturonase Production and Virulence in the Plant Pathogen Erwinia carotovora subsp. carotovora

2000 ◽  
Vol 13 (4) ◽  
pp. 447-455 ◽  
Author(s):  
Diana Flego ◽  
Reet Marits ◽  
Anders R. B. Eriksson ◽  
Viia Kõiv ◽  
Maj-Brit Karlsson ◽  
...  
Keyword(s):  
Plant Pathogen ◽  
Transcriptional Activation ◽  
Plant Cell Wall ◽  
Extracellular Enzymes ◽  
Regulatory System ◽  
Erwinia Carotovora ◽  
Virulence Determinants ◽  
Cell Wall Degrading Enzymes ◽  
Two Component ◽  
Specific Regulation

Genes coding for the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, the plant cell wall-degrading enzymes, are under the coordinate control of global regulator systems including both positive and negative factors. In addition to this global control, some virulence determinants are subject to specific regulation. We have previously shown that mutations in the pehR locus result in reduced virulence and impaired production of one of these enzymes, an endopolygalacturonase (PehA). In contrast, these pehR strains produce essentially wild-type levels of other extracellular enzymes including pectate lyases and cellulases. In this work, we characterized the pehR locus and showed that the DNA sequence is composed of two genes, designated pehR and pehS, present in an operon. Mutations in either pehR or pehS caused a Peh-negative phenotype and resulted in reduced virulence on tobacco seedlings. Complementation experiments indicated that both genes are required for transcriptional activation of the endopolygalacturonase gene, pehA, as well as restoration of virulence. Structural characterization of the pehR-pehS operon demonstrated that the corresponding polypeptides are highly similar to the two-component transcriptional regulators PhoP-PhoQ of both Escherichia coli and Salmonella typhimurium. Functional similarity of PehR-PehS with PhoP-PhoQ of E. coli and S. typhimurium was demonstrated by genetic complementation.

scholarly journals Genomic and phenotypic biology of novel strains of Dickeya zeae isolated from pineapple and taro in Hawaii: insights into genome plasticity, pathogenicity, and virulence determinants

2021 ◽  
Author(s):  
Gamze Boluk ◽  
Dario Arizala ◽  
Shefali Dobhal ◽  
Jingxin Zhang ◽  
John Hu ◽  
...  
Keyword(s):  
Plant Pathogen ◽  
Crop Production ◽  
Plant Cell Wall ◽  
Extracellular Enzymes ◽  
Ananas Comosus ◽  
Virulence Determinants ◽  
Secretion Systems ◽  
Genome Database ◽  
Wide Range ◽  
Complete Genomes

ABSTRACTDickeya zeae, a bacterial plant pathogen in the family Pectobacteriaceae, is responsible for a wide range of diseases on potato, maize, rice, banana, pineapple, taro and ornamentals and significantly reduces crop production; D. zeae causes soft rot of taro (Colocasia esculenta) and heart rot of pineapple (Ananas comosus). In this study, we used Pacific Biosciences to sequence two high quality complete genomes of novel strains of D. zeae: PL65 (size - 4.74997 MB; depth - 701; GC - 53.3%) and A5410 (size - 4.7792 MB; depth - 558; GC - 53.6%) isolated from economically important Hawaiian crops, taro and pineapple, respectively. Additional complete genomes of D. zeae representing two additional hosts (rice and banana), and other species for taxonomic comparison, were retrieved from the NCBI GenBank genome database. The genomic analyses indicated truncated type III and IV secretion systems (T3SS and T4SS) in the taro strain, which only harbors 1 and 2 genes of T3SS and T4SS, respectively, and showed high heterogeneity in the type VI secretion system. Unlike the EC1 strain, neither the PL65 nor the A5410 genome harbors the zeamine biosynthesis gene cluster, which plays a key role in bacterial virulence. The ANI and dDDH percentages between the two genomes were 94.47 and 57.00, respectively. In this study, we compared major virulence factors (plant cell wall-degrading extracellular enzymes and protease) produced by D. zeae strains and virulence ability on taro corms and pineapple. Both strains produced protease, pectate lyases and cellulases but no significant quantitative differences were observed (p>0.05) among the strains. All the strains produced symptoms on taro corms and pineapple leaves. Strain PL65 developed symptoms faster than the others. Our study highlights genetic constituents of pathogenicity determinants and genomic heterogeneity that will help understand the virulence mechanisms and aggressiveness of this plant pathogen.

scholarly journals Oligogalacturonide-Mediated Induction of a Gene Involved in Jasmonic Acid Synthesis in Response to the Cell-Wall-Degrading Enzymes of the Plant Pathogen Erwinia carotovora

1999 ◽  
Vol 12 (7) ◽  
pp. 640-644 ◽  
Author(s):  
Cecilia Norman ◽  
Sabina Vidal ◽  
E. Tapio Palva
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Extracellular Enzymes ◽  
Erwinia Carotovora ◽  
Acid Synthesis ◽  
Allene Oxide ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
High Sequence Homology ◽  
Oxide Synthase

Identification of Arabidopsis thaliana genes responsive to plant cell-wall-degrading enzymes of Erwinia carotovora subsp. carotovora led to the isolation of a cDNA clone with high sequence homology to the gene for allene oxide synthase, an enzyme involved in the biosynthesis of jasmonates. Expression of the corresponding gene was induced by the extracellular enzymes from this pathogen as well as by treatment with methyl jasmonate and short oligogalacturonides (OGAs). This suggests that OGAs are involved in the induction of the jasmonate pathway during plant defense response to E. carotovora subsp. carotovora attack.

scholarly journals Quorum Sensing in the Plant Pathogen Erwinia carotovora subsp. carotovora: The Role of expREcc

2000 ◽  
Vol 13 (4) ◽  
pp. 384-393 ◽  
Author(s):  
Robert A. Andersson ◽  
Anders R. B. Eriksson ◽  
Riikka Heikinheimo ◽  
Andres Mäe ◽  
Minna Pirhonen ◽  
...  
Keyword(s):  
Plant Pathogen ◽  
Sequence Similarity ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Open Reading Frames ◽  
Amino Acid Sequence Similarity ◽  
Virulence Determinants ◽  
Cell Wall Degrading Enzymes ◽  
Signal Molecule

The production of the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule N-(3-oxohexanoyl)-l-homoserine lactone (OHHL). OHHL is synthesized by the product of the expI/carI gene. Linked to expI we found a gene encoding a putative transcriptional regulator of the LuxR-family. This gene, expREcc, is transcribed convergently to the expI gene and the two open reading frames are partially overlapping. The ExpREcc protein showed extensive amino acid sequence similarity to the repressor EsaR from Pantoea stewartii subsp. stewartii(formerly Erwinia stewartii subsp. stewartii) and to the ExpREch protein of Erwinia chrysanthemi. Inactivation of the E. carotovora subsp. carotovora expREcc gene caused no decrease in virulence or production of virulence determinants in vitro. In contrast, there was a slight increase in the maceration capacity of the mutant strain. The effects of ExpREcc were probably mediated by changes in OHHL levels. Inactivation of expREcc resulted in increased OHHL levels during early logarithmic growth. In addition, over-expression of expREcc caused a clear decrease in the production of virulence determinants and part of this effect was likely to be caused by OHHL binding to ExpREcc. ExpREcc did not appear to exhibit transcriptional regulation of expI, but the effect on OHHL was apparently due to other mechanisms.

scholarly journals Global Regulators ExpA (GacA) and KdgR Modulate Extracellular Enzyme Gene Expression Through the RsmA-rsmB System in Erwinia carotovora subsp. carotovora

2001 ◽  
Vol 14 (8) ◽  
pp. 931-938 ◽  
Author(s):  
Heidi Hyytiäinen ◽  
Marcos Montesano ◽  
E. Tapio Palva
Keyword(s):  
Transcriptional Activation ◽  
Enzyme Production ◽  
Plant Cell Wall ◽  
Extracellular Enzyme ◽  
Erwinia Carotovora ◽  
Positive Control ◽  
Northern Analysis ◽  
Virulence Determinants ◽  
Regulatory Pathways ◽  
Global Regulators

The production of the main virulence determinants, the extracellular plant cell wall-degrading enzymes, and hence virulence of Erwinia carotovora subsp. carotovora is controlled by a complex regulatory network. One of the global regulators, the response regulator ExpA, a GacA homolog, is required for transcriptional activation of the extracellular enzyme genes of this soft-rot pathogen. To elucidate the mechanism of ExpA control as well as interactions with other regulatory systems, we isolated second-site transposon mutants that would suppress the enzyme-negative phenotype of an expA (gacA) mutant. Inactivation of kdgR resulted in partial restoration of extracellular enzyme production and virulence to the expA mutant, suggesting an interaction between the two regulatory pathways. This interaction was mediated by the RsmA-rsmB system. Northern analysis was used to show that the regulatory rsmB RNA was under positive control of ExpA. Conversely, the expression of rsmA encoding a global repressor was under negative control of ExpA and positive control of KdgR. This study indicates a central role for the RsmA-rsmB regulatory system during pathogenesis, integrating signals from the ExpA (GacA) and KdgR global regulators of extracellular enzyme production in E. carotovora subsp. carotovora.

scholarly journals A Novel Plant Ferredoxin-Like Protein and the Regulator Hor Are Quorum-Sensing Targets in the Plant Pathogen Erwinia carotovora

2008 ◽  
Vol 21 (7) ◽  
pp. 967-978 ◽  
Author(s):  
Solveig Sjöblom ◽  
Heidi Harjunpää ◽  
Günter Brader ◽  
E. Tapio Palva
Keyword(s):  
Oxidative Stress ◽  
Quorum Sensing ◽  
Stress Tolerance ◽  
Plant Cell Wall ◽  
Heterotrophic Bacteria ◽  
Erwinia Carotovora ◽  
Virulence Determinants ◽  
Cell Wall Degrading Enzymes ◽  
Plant Host ◽  
Oxidative Stress Tolerance

Quorum sensing (QS), a population-density-sensing mechanism, controls the production of the main virulence determinants, the plant cell-wall-degrading enzymes (PCWDEs) of the soft-rot phytopathogen Erwinia carotovora subsp. carotovora. In this study, we used random transposon mutagenesis with a gusA reporter construct to identify two new QS-controlled genes encoding the regulator Hor and a plant ferredoxin-like protein, FerE. The QS control of the identified genes was executed by the QS regulators ExpR1 and ExpR2 and mediated by the global repressor RsmA. Hor was shown to contribute to bacterial virulence at least partly through its control of PCWDE production. Our results showed that FerE contributes to oxidative stress tolerance and in planta fitness of the bacteria and suggest that QS could be central to control of oxidative stress tolerance. The presence of the FerE protein appears to be rather unique in heterotrophic bacteria and suggests an acquisition of the corresponding gene from plant host by horizontal gene transfer.

scholarly journals Two-Component Regulators Involved in the Global Control of Virulence in Erwinia carotovora subsp. carotovora

1998 ◽  
Vol 11 (8) ◽  
pp. 743-752 ◽  
Author(s):  
Anders R. B. Eriksson ◽  
Robert A. Andersson ◽  
Minna Pirhonen ◽  
E. Tapio Palva
Keyword(s):  
Cell Wall ◽  
Gene Product ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Response Regulator ◽  
Erwinia Carotovora ◽  
Sensor Kinase ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes ◽  
Two Component

Production of extracellular, plant cell wall degrading enzymes, the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, is coordinately controlled by a complex regulatory network. Insertion mutants in the exp (extracellular enzyme production) loci exhibit pleiotropic defects in virulence and the growth-phase-dependent transcriptional activation of genes encoding extracellular enzymes. Two new exp mutations, designated expA and expS, were characterized. Introduction of the corresponding wild-type alleles to the mutants complemented both the lack of virulence and the impaired production of plant cell wall degrading enzymes. The expA gene was shown to encode a 24-kDa polypeptide that is structurally and functionally related to the uvrY gene product of Escherichia coli and the GacA response regulator of Pseudomonas fluorescens. Functional similarity of expA and uvrY was demonstrated by genetic complementation. The expA gene is organized in an operon together with a uvrC-like gene, identical to the organization of uvrY and uvrC in E. coli. The unlinked expS gene encodes a putative sensor kinase that shows 92% identity to the recently described rpfA gene product from another E. carotovora subsp. carotovora strain. Our data suggest that ExpS and ExpA are members of two-component sensor kinase and response regulator families, respectively. These two proteins might interact in controlling virulence gene expression in E. carotovora subsp. carotovora.

scholarly journals The Erwinia chrysanthemi 3937 PhoQ Sensor Kinase Regulates Several Virulence Determinants

2006 ◽  
Vol 188 (8) ◽  
pp. 3088-3098 ◽  
Author(s):  
Balakrishnan Venkatesh ◽  
Lavanya Babujee ◽  
Hui Liu ◽  
Pete Hedley ◽  
Takashi Fujikawa ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Regulatory System ◽  
Soft Rot ◽  
Erwinia Chrysanthemi ◽  
Pcr Analysis ◽  
Sensor Kinase ◽  
Virulence Determinants ◽  
Gene Encoding ◽  
Reverse Transcription Pcr ◽  
Two Component

ABSTRACT The PhoPQ two-component system regulates virulence factors in Erwinia chrysanthemi, a pectinolytic enterobacterium that causes soft rot in several plant species. We characterized the effect of a mutation in phoQ, the gene encoding the sensor kinase PhoQ of the PhoPQ two-component regulatory system, on the global transcriptional profile of E. chrysanthemi using cDNA microarrays and further confirmed our results by quantitative reverse transcription-PCR analysis. Our results indicate that a mutation in phoQ affects transcription of at least 40 genes, even in the absence of inducing conditions. Enhanced expression of several genes involved in iron metabolism was observed in the mutant, including that of the acs operon that is involved in achromobactin biosynthesis and transport. This siderophore is required for full virulence of E. chrysanthemi, and its expression is governed by the global repressor protein Fur. Changes in gene expression were also observed for membrane transporters, stress-related genes, toxins, and transcriptional regulators. Our results indicate that the PhoPQ system governs the expression of several additional virulence factors and may also be involved in interactions with other regulatory systems.

scholarly journals A Metabolic Regulator Modulates Virulence and Quorum Sensing Signal Production in Pectobacterium atrosepticum

2013 ◽  
Vol 26 (3) ◽  
pp. 356-366 ◽  
Author(s):  
Marion F. Cubitt ◽  
Peter E. Hedley ◽  
Neil R. Williamson ◽  
Jenny A. Morris ◽  
Emma Campbell ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Plant Cell Wall ◽  
Homoserine Lactone ◽  
Insertion Mutation ◽  
Virulence Determinants ◽  
Methionine Biosynthesis ◽  
Cell Wall Degrading Enzymes ◽  
Pectobacterium Atrosepticum ◽  
Small Regulatory Rna ◽  
The Impact

Plant cell wall–degrading enzymes (PCWDE) are key virulence determinants in the pathogenesis of the potato pathogen Pectobacterium atrosepticum. In this study, we report the impact on virulence of a transposon insertion mutation in the metJ gene that codes for the repressor of the methionine biosynthesis regulon. In a mutant strain defective for the small regulatory RNA rsmB, PCWDE are not produced and virulence in potato tubers is almost totally abolished. However, when the metJ gene is disrupted in this background, the rsmB– phenotype is suppressed and virulence and PCWDE production are restored. Additionally, when metJ is disrupted, production of the quorum-sensing signal, N-(3-oxohexanoyl)-homoserine lactone, is increased. The metJ mutant strains showed pleiotropic transcriptional impacts affecting approximately a quarter of the genome. Genes involved in methionine biosynthesis were most highly upregulated but many virulence-associated transcripts were also upregulated. This is the first report of the impact of the MetJ repressor on virulence in bacteria.

scholarly journals A Novel Class of Heat and Secretion Stress-Responsive Genes Is Controlled by the Autoregulated CssRS Two-Component System of Bacillus subtilis

2002 ◽  
Vol 184 (20) ◽  
pp. 5661-5671 ◽  
Author(s):  
Elise Darmon ◽  
David Noone ◽  
Anne Masson ◽  
Sierd Bron ◽  
Oscar P. Kuipers ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Heat Stress ◽  
Transcriptional Activation ◽  
Cellular Response ◽  
Regulatory Region ◽  
Regulatory System ◽  
Secretion Stress ◽  
Two Component ◽  
High Level ◽  
Inducible Genes

ABSTRACT Bacteria need dedicated systems that allow appropriate adaptation to the perpetual changes in their environments. In Bacillus subtilis, two HtrA-like proteases, HtrA and HtrB, play critical roles in the cellular response to secretion and heat stresses. Transcription of these genes is induced by the high-level production of a secreted protein or by a temperature upshift. The CssR-CssS two-component regulatory system plays an essential role in this transcriptional activation. Transcription of the cssRS operon is autoregulated and can be induced by secretion stress, by the absence of either HtrA or HtrB, and by heat stress in a HtrA null mutant strain. Two start sites are used for cssRS transcription, only one of which is responsive to heat and secretion stress. The divergently transcribed htrB and cssRS genes share a regulatory region through which their secretion and heat stress-induced expression is linked. This study shows that CssRS-regulated genes represent a novel class of heat-inducible genes, which is referred to as class V and currently includes two genes: htrA and htrB.

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