Molecular Characterization and Expression of the <i>Erwinia carotovora hrpN<sub>Ecc</sub></i> Gene, Which Encodes an Elicitor of the Hypersensitive Reaction

Mukherjee, Asita; Cui, Yaya; Liu, Yang; Chatterjee, Arun

doi:10.1094/mpmi.1997.10.4.462

Cited by 78 publications

(71 citation statements)

References 49 publications

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“…Further investigation of P. carotovorum virulence pathways led to the discovery of a quorum-sensing signal used to alter gene expression in response to changes in cell population density (338,(341)(342)(343)(344)(345). The quorum-sensing signal N-(3-oxohexanoyl)-L-homoserine lactone (acyl homoserine lactone [AHL]) is required for production of P. carotovorum virulence factors and related products, including the previously mentioned cell wall-degrading enzymes, antibiotics, hypersensitive responses, and the T3SS (346,347).…”

Section: Plant Pathogensmentioning

confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

295

400

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SUMMARY Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional gene expression, play important roles in the expression of virulence factors of numerous proteobacterial pathogens. To accomplish these tasks, CsrA binds to the 5′ untranslated and/or early coding regions of mRNAs and alters translation, mRNA turnover, and/or transcript elongation. CsrA activity is regulated by noncoding small RNAs (sRNAs) that contain multiple CsrA binding sites, which permit them to sequester multiple CsrA homodimers away from mRNA targets. Environmental cues sensed by two-component signal transduction systems and other regulatory factors govern the expression of the CsrA-binding sRNAs and, ultimately, the effects of CsrA on secretion systems, surface molecules and biofilm formation, quorum sensing, motility, pigmentation, siderophore production, and phagocytic avoidance. This review presents the workings of the Csr system, the paradigm shift that it generated for understanding posttranscriptional regulation, and its roles in virulence networks of animal and plant pathogens.

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Section: Plant Pathogensmentioning

confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

295

400

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“…This pathogen also produces harpins, protein elicitors of the hypersensitive response (HR) Necrotroph Attacks on Plants 3 of 34 (Cui et al, 1996;Mukherjee et al, 1997). Pathogen produced CWDEs and harpins are transported to the host via the type II/ III secretion system (Sandkvist, 2001; Alfano and Collmer, 2004).…”

Section: Examples Of Necrotrophic Infection Strategiesmentioning

confidence: 99%

Necrotroph Attacks on Plants: Wanton Destruction or Covert Extortion?

Laluk

Mengiste

2010

The Arabidopsis Book

204

168

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Necrotrophic pathogens cause major pre-and post-harvest diseases in numerous agronomic and horticultural crops infl icting signifi cant economic losses. In contrast to biotrophs, obligate plant parasites that infect and feed on living cells, necrotrophs promote the destruction of host cells to feed on their contents. This difference underpins the divergent pathogenesis strategies and plant immune responses to biotrophic and necrotrophic infections. This chapter focuses on Arabidopsis immunity to necrotrophic pathogens. The strategies of infection, virulence and suppression of host defenses recruited by necrotrophs and the variation in host resistance mechanisms are highlighted. The multiplicity of intraspecifi c virulence factors and species diversity in necrotrophic organisms corresponds to variations in host resistance strategies. Resistance to host-specifi c necrotophs is monogenic whereas defense against broad host necrotrophs is complex, requiring the involvement of many genes and pathways for full resistance. Mechanisms and components of immunity such as the role of plant hormones, secondary metabolites, and pathogenesis-related proteins are presented. We will discuss the current state of knowledge of Arabidopsis immune responses to necrotrophic pathogens, the interactions of these responses with other defense pathways, and contemplate on the directions of future research.: e0136. of 34The Arabidopsis Book Infection by fungal necrotrophs generally involves stages of conidial attachment, germination, host penetration, primary lesion formation, lesion expansion, and tissue maceration followed by sporulation (Prins et al., 2000). Following germination, penetration may be achieved by active mechanisms such as appressoria formation and enzymatic degradation or passively through prior infection or wound sites as well as stomates (Prins et al., 2000). After entry, tissue is decomposed through further cellular dismantling using many of the lytic enzymes employed for initial penetration as well as toxic levels of reactive oxygen species (ROS). Many necrotrophs produce various low-molecular weight phytotoxic metabolites, ranging from host-specifi c to those having adverse effects on many diverse species (van Kan, 2006). Others secrete phytotoxic proteins known to induce necrosis, with the vast majority of broad host necrotrophs producing multiples of both (Pemberton and Salmond, 2004;Gijzen and Nurnberger, 2006;Choquer et al., 2007). Throughout infection, these fungi also actively manipulate host cellular machinery in order to suppress defenses and/or aid in disease progression. Some necrotrophs infl uence host phytohormone levels or employ their own hormone biosynthesis thereby disrupting defense signaling (Prins et al., 2000;Sharon et al., 2004). Others have adapted mechanisms to detoxify host metabolites that interfere with virulence (Morrissey and Osbourn, 1999).Overall, bacterial necrotrophs follow a similar mode of pathogenesis to their fungal counterparts, secreting virulence factors into host tissue to induc...

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“…The protein concentrations were determined with a bicinchoninic acid protein assay kit (Pierce, Rockford, IL) according to the manufacturer's specifications. Western blot analysis of the total bacterial protein was performed as described in Mukherjee et al (38). The antiserum raised against RsmA of Ecc71 (10) was used as probe.…”

Section: Detection Of Ahls By Analytical Thin-layer Chromatography (Tmentioning

confidence: 99%

“…These enzymes acting in concert with Prt and Cel cause degradation of plant cell wall components triggering cell separation and cell death. Harpins are required for the elicitation of the hypersensitive response and also for symptom production in Arabidopsis thaliana (38,46). Aside from extracellular proteins, many of these bacteria produce antibiotics and other secondary metabolites (5).…”

mentioning

confidence: 99%

ExpR, a LuxR Homolog ofErwinia carotovorasubsp.carotovora, Activates Transcription ofrsmA, Which Specifies a Global Regulatory RNA-Binding Protein

Cui¹,

Chatterjee²,

Hasegawa³

et al. 2005

J Bacteriol

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N-acyl homoserine lactone (AHL) is required by Erwinia carotovora subspecies for the expression of various traits, including extracellular enzyme and protein production and pathogenicity. Previous studies with E. carotovora subsp. carotovora have shown that AHL deficiency causes the production of high levels of RsmA, an RNA binding protein that functions as a global negative regulator of extracellular enzymes and proteins and secondary metabolites (Rsm, regulator of secondary metabolites). We document here that ExpR, a putative AHL receptor belonging to the LuxR family of regulators, activates RsmA production. In the absence of AHL, an ExpR ؉ E. carotovora subsp. carotovora strain compared to its ExpR ؊ mutant, produces higher levels of rsmA RNA and better expresses an rsmA-lacZ transcriptional fusion. Moreover, the expression of the rsmA-lacZ fusion in Escherichia coli is much higher in the presence of expR 71 (the expR gene of E. carotovora subsp. carotovora strain Ecc71) than in its absence. We also show that purified preparation of MBP-ExpR 71 binds (MBP, maltose binding protein) rsmA DNA. By contrast, MBP-ExpR 71 does not bind ahlI (gene for AHL synthase), pel-1 (gene for pectate lyase), or rsmB (gene for regulatory RNA that binds RsmA), nor does ExpR 71 activate expression of these genes. These observations strongly suggest transcriptional activation of rsmA resulting from a direct and specific interaction between ExpR 71 and the rsmA promoter. Several lines of evidence establish that N-3-oxohexanoyl-L-homoserine lactone (3-oxo-C6-HL), the major AHL analog produced by E. carotovora subsp. carotovora strain Ecc71, inhibits ExpR 71 -mediated activation of rsmA expression. These findings for the first time establish that the expR effect in E. carotovora subsp. carotovora is channeled via RsmA, a posttranscriptional regulator of E. carotovora subspecies, and AHL neutralizes this ExpR effect.Erwinia carotovora subspecies cause soft-rotting or tissue macerating disease in many plants and plant organs. Their capacity to cause rotting depends heavily upon their ability to produce secreted proteins and enzymes (2, 6). These bacteria utilize Type I, Type II, and Type III secretion systems to translocate proteins into the milieu. Proteases (Prt) are secreted by the Type I system, pectate lyase (Pel), polygalacturonase (Peh), and cellulase (Cel) are exported via the Type II system, and Harpin and other putative effectors are secreted by the Type III system (18, 48). Of the effectors and enzymes secreted by these bacteria, especially significant in the context of plant tissue maceration are the pectinases such as Pel, Peh, and pectin lyase (Pnl). These enzymes acting in concert with Prt and Cel cause degradation of plant cell wall components triggering cell separation and cell death. Harpins are required for the elicitation of the hypersensitive response and also for symptom production in Arabidopsis thaliana (38,46). Aside from extracellular proteins, many of these bacteria produce antibiotics and other secondary meta...

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Molecular Characterization and Expression of the Erwinia carotovora hrpN_Ecc Gene, Which Encodes an Elicitor of the Hypersensitive Reaction

Cited by 78 publications

References 49 publications

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Necrotroph Attacks on Plants: Wanton Destruction or Covert Extortion?

ExpR, a LuxR Homolog ofErwinia carotovorasubsp.carotovora, Activates Transcription ofrsmA, Which Specifies a Global Regulatory RNA-Binding Protein

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Molecular Characterization and Expression of the Erwinia carotovora hrpNEcc Gene, Which Encodes an Elicitor of the Hypersensitive Reaction

Cited by 78 publications

References 49 publications

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Necrotroph Attacks on Plants: Wanton Destruction or Covert Extortion?

ExpR, a LuxR Homolog ofErwinia carotovorasubsp.carotovora, Activates Transcription ofrsmA, Which Specifies a Global Regulatory RNA-Binding Protein

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Product

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Molecular Characterization and Expression of the Erwinia carotovora hrpN_Ecc Gene, Which Encodes an Elicitor of the Hypersensitive Reaction