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 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 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 Use of the Galleria mellonella Caterpillar as a Model Host To Study the Role of the Type III Secretion System in Pseudomonas aeruginosa Pathogenesis

2003 ◽  
Vol 71 (5) ◽  
pp. 2404-2413 ◽  
Author(s):  
Sachiko Miyata ◽  
Monika Casey ◽  
Dara W. Frank ◽  
Frederick M. Ausubel ◽  
Eliana Drenkard
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Galleria Mellonella ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Triple Mutant ◽  
Type Iii ◽  
Wax Moth

ABSTRACT Nonvertebrate model hosts represent valuable tools for the study of host-pathogen interactions because they facilitate the identification of bacterial virulence factors and allow the discovery of novel components involved in host innate immune responses. In this report, we determined that the greater wax moth caterpillar Galleria mellonella is a convenient nonmammalian model host for study of the role of the type III secretion system (TTSS) in Pseudomonas aeruginosa pathogenesis. Based on the observation that a mutation in the TTSS pscD gene of P. aeruginosa strain PA14 resulted in a highly attenuated virulence phenotype in G. mellonella, we examined the roles of the four known effector proteins of P. aeruginosa (ExoS, ExoT, ExoU, and ExoY) in wax moth killing. We determined that in P. aeruginosa strain PA14, only ExoT and ExoU play a significant role in G. mellonella killing. Strain PA14 lacks the coding sequence for the ExoS effector protein and does not seem to express ExoY. Moreover, using ΔexoU ΔexoY, ΔexoT ΔexoY, and ΔexoT ΔexoU double mutants, we determined that individual translocation of either ExoT or ExoU is sufficient to obtain nearly wild-type levels of G. mellonella killing. On the other hand, data obtained with a ΔexoT ΔexoU ΔexoY triple mutant and a ΔpscD mutant suggested that additional, as-yet-unidentified P. aeruginosa components of type III secretion are involved in virulence in G. mellonella. A high level of correlation between the results obtained in the G. mellonella model and the results of cytopathology assays performed with a mammalian tissue culture system validated the use of G. mellonella for the study of the P. aeruginosa TTSS.

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