Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review

2020 ◽  
Author(s):  
Xiaochen Yuan ◽  
Michelle T. Hulin ◽  
George W. Sundin
Keyword(s):  
Type Iii Secretion ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii

scholarly journals Discovery of Plant Phenolic Compounds That Act as Type III Secretion System Inhibitors or Inducers of the Fire Blight Pathogen, Erwinia amylovora

2013 ◽  
Vol 79 (18) ◽  
pp. 5424-5436 ◽  
Author(s):  
Devanshi Khokhani ◽  
Chengfang Zhang ◽  
Yan Li ◽  
Qi Wang ◽  
Quan Zeng ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Virulence Factors ◽  
Type Iii Secretion ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Fluorescent Protein ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Content Type ◽  
Type Iii

ABSTRACTErwinia amylovoracauses a devastating disease called fire blight in rosaceous plants. The type III secretion system (T3SS) is one of the important virulence factors utilized byE. amylovorain order to successfully infect its hosts. By using a green fluorescent protein (GFP) reporter construct combined with a high-throughput flow cytometry assay, a library of phenolic compounds and their derivatives was studied for their ability to alter the expression of the T3SS. Based on the effectiveness of the compounds on the expression of the T3SS pilus, the T3SS inhibitors 4-methoxy-cinnamic acid (TMCA) and benzoic acid (BA) and one T3SS inducer,trans-2-(4-hydroxyphenyl)-ethenylsulfonate (EHPES), were chosen for further study. Both the T3SS inhibitors (TMCA and BA) and the T3SS inducer (EHPES) were found to alter the expression of T3SS through the HrpS-HrpL pathway. Additionally, TMCA altered T3SS expression through thersmBEa-RsmAEasystem. Finally, we found that TMCA and BA weakened the hypersensitive response (HR) in tobacco by suppressing the T3SS ofE. amylovora. In our study, we identified phenolic compounds that specifically targeted the T3SS. The T3SS inhibitor may offer an alternative approach to antimicrobial therapy by targeting virulence factors of bacterial pathogens.

scholarly journals Expression of the type III secretion system genes in epiphytic Erwinia amylovora cells on apple stigmas benefits endophytic infection at the hypanthium

2020 ◽  
Author(s):  
Zhouqi Cui ◽  
Regan B. Huntley ◽  
Neil P Schultes ◽  
Kaleem U. Kakar ◽  
Quan Zeng
Keyword(s):  
Type Iii Secretion ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Subsequent Infection ◽  
Type Iii ◽  
Primary Location ◽  
Important Virulence Factor

AbstractErwinia amylovora causes fire blight on rosaceous plants. Flower surfaces are the primary location in the fire blight infection pathway. Here E. amylovora proliferates on stigmatic and hypanthium surfaces as epiphytic growth, followed by subsequent endophytic (intercellular) infection in the hypanthium. The type III secretion system (T3SS) is an important virulence factor in E. amylovora. Although the role of T3SS during the endophytic infection is well characterized, its expression during the epiphytic colonization and role in the subsequent infection is less understood. Here, we investigated the T3SS expression in epiphytic E. amylovora on stigma and hypanthium of apple flowers, under different relative humidities (RH). On stigma surfaces, T3SS was expressed in a high percentage of E. amylovora cells, and its expression promotes epiphytic growth. On hypanthium surfaces however, T3SS was expressed in fewer E. amylovora cells than on the stigma, and displayed no correlation with epiphytic growth, even though T3SS expression is essential for infection. E. amylovora cells grown on stigmatic surfaces and then flushed down to the hypanthium displayed a higher level of T3SS expression than cells grown on the hypanthium surface alone. Furthermore, cells pre-cultured on stigma before inoculation on hypanthium caused more infections than cells pre-cultured in a T3SS-repressive medium then used as inoculum, suggesting that the T3SS induction during the stigmatic epiphytic colonization may be beneficial for the subsequent infection. Finally, the epiphytic expression of T3SS is influenced by RH. Higher percentage of stigmatic E. amylovora cells expressed T3SS under high RH than under low RH.

scholarly journals Expression of the Type III Secretion System Genes in Epiphytic Erwinia amylovora Cells on Apple Stigmas Benefits Endophytic Infection at the Hypanthium

2021 ◽  
Author(s):  
Zhouqi Cui ◽  
Regan B. Huntley ◽  
Neil P Schultes ◽  
Kaleem U. Kakar ◽  
Ching-Hong Yang ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Erwinia Amylovora ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Subsequent Infection ◽  
Type Iii ◽  
Entry Points ◽  
Important Virulence Factor ◽  
Open Access Article

Erwinia amylovora causes fire blight on rosaceous plants. One of the major entry points of E. amylovora into hosts is flowers, where E. amylovora proliferates epiphytically on stigmatic and hypanthium surfaces and, subsequently, causes endophytic infection at the hypanthium. The type III secretion system (T3SS) is an important virulence factor in E. amylovora. Although the role of T3SS during endophytic infection is well characterized, its expression during epiphytic colonization and role in the subsequent infection is less understood. Here, we investigated T3SS gene expression in epiphytic E. amylovora on stigma and hypanthium of apple flowers under different relative humidities (RH). On stigma surfaces, T3SS was expressed in a high percentage of E. amylovora cells, and its expression promoted epiphytic growth. On hypanthium surfaces, however, T3SS was expressed in fewer E. amylovora cells than on the stigma, and displayed no correlation with epiphytic growth, even though T3SS expression is essential for infection. E. amylovora cells grown on stigmatic surfaces and then flushed down to the hypanthium displayed a higher level of T3SS expression than cells grown on the hypanthium surface alone. Furthermore, E. amylovora cells precultured on stigma had a higher potential to infect flowers than E. amylovora cells precultured in a T3SS-repressive medium. This suggests that T3SS induction during the stigmatic epiphytic colonization may be beneficial for subsequent infection. Finally, epiphytic expression of T3SS was influenced by RH. Higher percentage of stigmatic E. amylovora cells expressed T3SS under high RH than under low RH. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals HrpG and HrpV proteins from the Type III secretion system of Erwinia amylovora form a stable heterodimer

2015 ◽  
Vol 362 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Anastasia D. Gazi ◽  
Spyridoula Charova ◽  
Michalis Aivaliotis ◽  
Nicholas J. Panopoulos ◽  
Michael Kokkinidis
Keyword(s):  
Type Iii Secretion ◽  
Erwinia Amylovora ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii

Erwinia amylovora modifies phenolic profiles of susceptible and resistant apple through its type III secretion system

2008 ◽  
Vol 132 (3) ◽  
pp. 262-271 ◽  
Author(s):  
Isabelle Pontais ◽  
Dieter Treutter ◽  
Jean-Pierre Paulin ◽  
Marie-Noëlle Brisset
Keyword(s):  
Type Iii Secretion ◽  
Erwinia Amylovora ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii ◽  
Phenolic Profiles

scholarly journals ClpXP-Dependent RpoS Degradation Enables Full Activation of Type III Secretion System, Amylovoran Production, and Motility in Erwinia amylovora

2017 ◽  
Vol 107 (11) ◽  
pp. 1346-1352 ◽  
Author(s):  
Jae Hoon Lee ◽  
Youfu Zhao
Keyword(s):  
Type Iii Secretion ◽  
Erwinia Amylovora ◽  
Critical Role ◽  
Type Iii Secretion System ◽  
Potential Interaction ◽  
Secretion System ◽  
Posttranslational Regulation ◽  
Type Iii ◽  
Blight Disease

Erwinia amylovora, the causal agent of fire blight disease of apple and pear, employs intracellular proteases, including Lon and ClpXP, for posttranslational regulation of various cellular proteins. It has been shown that Lon plays a critical role in E. amylovora virulence by directly targeting type III secretion system (T3SS) proteins and the Rcs phosphorelay system. In this study, we genetically examined the role of ClpXP and its potential interaction with Lon in E. amylovora. Mutation in clpXP diminished the expression of the T3SS, reduced exopolysaccharide amylovoran production and motility, and resulted in delayed disease progress. Western blot analyses showed highly accumulated RpoS proteins in the clpXP mutant. Moreover, mutation of rpoS in the clpXP mutant background rescued the expression of the T3SS and amylovoran production, suggesting that ClpXP-dependent RpoS degradation positively affects virulence traits. Interestingly, lack of both ClpXP and Lon resulted in significantly reduced virulence but increased expression of the T3SS and amylovoran production. However, this phenomenon was independent of RpoS accumulation, suggesting that ClpXP and Lon are indispensable for full virulence in E. amylovora.

scholarly journals The Bacterial Alarmone (p)ppGpp Activates the Type III Secretion System in Erwinia amylovora

2015 ◽  
Vol 197 (8) ◽  
pp. 1433-1443 ◽  
Author(s):  
Veronica Ancona ◽  
Jae Hoon Lee ◽  
Tiyakhon Chatnaparat ◽  
Jinrok Oh ◽  
Jong-In Hong ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Sigma Factor ◽  
Pathogenic Bacteria ◽  
Erwinia Amylovora ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Content Type ◽  
Type Iii ◽  
Pathogenicity Factor ◽  
Small Proteins

ABSTRACTThe hypersensitive response and pathogenicity (hrp) type III secretion system (T3SS) is a key pathogenicity factor inErwinia amylovora. Previous studies have demonstrated that the T3SS inE. amylovorais transcriptionally regulated by a sigma factor cascade. In this study, the role of the bacterial alarmone ppGpp in activating the T3SS and virulence ofE. amylovorawas investigated using ppGpp mutants generated by Red recombinase cloning. The virulence of a ppGpp-deficient mutant (ppGpp0) as well as adksAmutant ofE. amylovorawas completely impaired, and bacterial growth was significantly reduced, suggesting that ppGpp is required for full virulence ofE. amylovora. Expression of T3SS genes was greatly downregulated in the ppGpp0anddksAmutants. Western blotting showed that accumulations of the HrpA protein in the ppGpp0anddksAmutants were about 10 and 4%, respectively, of that in the wild-type strain. Furthermore, higher levels of ppGpp resulted in a reduced cell size ofE. amylovora. Moreover, serine hydroxamate and α-methylglucoside, which induce amino acid and carbon starvation, respectively, activatedhrpAandhrpLpromoter activities inhrp-inducing minimal medium. These results demonstrated that ppGpp and DksA play central roles inE. amylovoravirulence and indicated thatE. amylovorautilizes ppGpp as an internal messenger to sense environmental/nutritional stimuli for regulation of the T3SS and virulence.IMPORTANCEThe type III secretion system (T3SS) is a key pathogenicity factor in Gram-negative bacteria. Fully elucidating how the T3SS is activated is crucial for comprehensively understanding the function of the T3SS, bacterial pathogenesis, and survival under stress conditions. In this study, we present the first evidence that the bacterial alarmone ppGpp-mediated stringent response activates the T3SS through a sigma factor cascade, indicating that ppGpp acts as an internal messenger to sense environmental/nutritional stimuli for the regulation of the T3SS and virulence in plant-pathogenic bacteria. Furthermore, the recovery of anspoTnull mutant, which displayed very unique phenotypes, suggested that small proteins containing a single ppGpp hydrolase domain are functional.

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