Type III Secretion Contributes to the Pathogenesis of the Soft-Rot Pathogen Erwinia carotovora: Partial Characterization of the hrp Gene Cluster

The virulence of soft-rot Erwinia species is dependent mainly upon secreted enzymes such as pectinases, pectin lyases, and proteases that cause maceration of plant tissue. Some soft-rot Erwinia spp. also harbor genes homologous to the hypersensitive reaction and pathogenesis (hrp) gene cluster, encoding components of the type III secretion system. The hrp genes are essential virulence determinants for numerous nonmacerating gram-negative plant pathogens but their role in the virulence of soft-rot Erwinia spp. is not clear. We isolated and characterized 11 hrp genes of Erwinia carotovora subsp. carotovora. Three putative σL-dependent Hrp box promoter sequences were found. The genes were expressed when the bacteria were grown in Hrp-inducing medium. The operon structure of the hrp genes was determined by mRNA hybridization, and the results were in accordance with the location of the Hrp boxes. An E. carotovora strain with mutated hrcC, an essential hrp gene, was constructed. The hrcC¯ strain was able to multiply and cause disease in Arabidopsis, but the population kinetics were altered so that growth was delayed during the early stages of infection.

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Use of a Pooled Transposon Mutation Grid to Demonstrate Roles in Disease Development for Erwinia carotovora subsp. atroseptica Putative Type III Secreted Effector (DspE/A) and Helper (HrpN) Proteins

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2004.17.9.943 ◽

2004 ◽

Vol 17 (9) ◽

pp. 943-950 ◽

Cited By ~ 53

Author(s):

Maria C. Holeva ◽

Kenneth S. Bell ◽

Lizbeth J. Hyman ◽

Anna O. Avrova ◽

Stephen C. Whisson ◽

...

Keyword(s):

Gene Cluster ◽

Plant Pathogens ◽

Erwinia Carotovora ◽

Soft Rot ◽

Disease Development ◽

Type Iii ◽

Novel Approach ◽

Related Plant ◽

Polymerase Chain ◽

Soft Rot Erwinia

Soft rot Erwinia spp., like other closely related plant pathogens, possess a type III secretion system (TTSS) (encoded by the hrp gene cluster) implicated in disease development. We report the sequence of the entire hrp gene cluster and adjacent dsp genes in Erwinia carotovora subsp. atroseptica SCRI1039. The cluster is similar in content and structural organization to that in E. amylovora. However, eight putative genes of unknown function located within the E. carotovora subsp. atroseptica cluster do not have homologues in the E. amylovora cluster. An arrayed set of Tn5 insertional mutants (mutation grid) was constructed and pooled to allow rapid isolation of mutants for any given gene by polymerase chain reaction screening. This novel approach was used to obtain mutations in two structural genes (hrcC and hrcV), the effector gene dspE/A, and the helper gene hrpN. An improved pathogenicity assay revealed that these mutations led to significantly reduced virulence, showing that both the putative E. carotovora subsp. atroseptica TTSS-delivered effector and helper proteins are required for potato infection.

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Injectisome T3SS Subunits As Potential Chaperones In The Extracellular Export of Pectobacterium Carotovorum Subsp. Carotovorum Bacteriocins Carocin S1 And Carocin S3 Secreted Via Flagellar T3SS

10.21203/rs.3.rs-590298/v1 ◽

2021 ◽

Author(s):

Hang-Cheng Chen ◽

Reymund C. Derilo ◽

Han-Ling Chen ◽

Tzu-Rung Li ◽

Ruchi Briam James S. Lagitnay ◽

...

Keyword(s):

Type Iii Secretion ◽

Insertional Mutagenesis ◽

Plant Pathogens ◽

Soft Rot ◽

Economic Losses ◽

Pectobacterium Carotovorum ◽

Secretion Systems ◽

Unique Type ◽

Bacterial Flagellum ◽

Type Iii

Abstract Pectobacterium carotovorum subsp. carotovorum (Pcc) causes soft-rot disease in a wide variety of plants resulting in economic losses worldwide. It produces various types of bacteriocin to compete against related plant pathogens. Studies on how bacteriocins are extracellularly secreted are conducted to understand the mechanism of interbacterial competition. In this study, the secretion of the low-molecular-weight bacteriocins (LMWB) Carocin S1 and Carocin S3 produced by a multiple-bacteriocin producing strain of Pcc, 89-H-4, was investigated. Tn5 insertional mutagenesis was used to generate a mutant, TH22-6, incapable of LMWBs secretion. Sequence and homology analyses of the gene disrupted by transposon Tn5 insertion revealed that the gene sctT, an essential component of the injectisome type III secretion machinery (T3aSS), is required for the secretion of the bacteriocins. This result raised a question regarding the nature of the secretion mechanism of Pcc bacteriocins which was previously discovered to be secreted via T3bSS, a system that utilizes the bacterial flagellum for extracellular secretions. Our previous report has shown that bacteriocin Carocin S1 cannot be secreted by mutants that are defective of T3bSS-related genes such as flhA, flhC, flhD and fliC. We knocked out several genes making up the significant structural components of both T3aSS and T3bSS. The findings led us to hypothesize the potential roles of the T3aSS-related proteins, SctT, SctU and SctV, as flagellar T3SS chaperones in the secretion of Pcc bacteriocins. This current discovery and the findings of our previous study helped us to conceptualize a unique Type III secretion system for bacteriocin extracellular export which is a hybrid of the injectisome and flagellar secretion systems.

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Phylogenetic evidence for extensive horizontal gene transfer of type III secretion system genes among enterobacterial plant pathogens

Microbiology ◽

10.1099/mic.0.029892-0 ◽

2009 ◽

Vol 155 (10) ◽

pp. 3187-3199 ◽

Cited By ~ 20

Author(s):

Marianna Naum ◽

Eric W. Brown ◽

Roberta J. Mason-Gamer

Keyword(s):

Gene Transfer ◽

Horizontal Gene Transfer ◽

Type Iii Secretion ◽

Plant Pathogens ◽

Virulence Genes ◽

Type Iii Secretion System ◽

Secretion System ◽

Virulence Determinants ◽

Type Iii ◽

Animal Pathogens

This study uses sequences from four genes, which are involved in the formation of the type III secretion apparatus, to determine the role of horizontal gene transfer in the evolution of virulence genes for the enterobacterial plant pathogens. Sequences of Erwinia, Brenneria, Pectobacterium, Dickeya and Pantoea were compared (a) with one another, (b) with sequences of enterobacterial animal pathogens, and (c) with sequences of plant pathogenic γ and β proteobacteria, to evaluate probable paths of lateral exchange leading to the current distribution of virulence determinants among these micro-organisms. Phylogenies were reconstructed based on hrcC, hrcR, hrcJ and hrcV gene sequences using parsimony and maximum-likelihood algorithms. Virulence gene phylogenies were also compared with several housekeeping gene loci in order to evaluate patterns of lateral versus vertical acquisition. The resulting phylogenies suggest that multiple horizontal gene transfer events have occurred both within and among the enterobacterial plant pathogens and plant pathogenic γ and β proteobacteria. hrcJ sequences are the most similar, exhibiting anywhere from 2 to 50 % variation at the nucleotide level, with the highest degree of variation present between plant and animal pathogen sequences. hrcV sequences are conserved among plant and animal pathogens at the N terminus. The C-terminal domain is conserved only among the enterobacterial plant pathogens, as are the hrcC and hrcR sequences. Additionally, hrcJ and hrcV sequence phylogenies suggest that at least some type III secretion system virulence genes from enterobacterial plant pathogens are related more closely to those of the genus Pseudomonas, a conclusion neither supported nor refuted by hrcC or hrcR.

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Pectobacterium parvum sp. nov., having a Salmonella SPI-1-like Type III secretion system and low virulence

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijsem.0.004057 ◽

2020 ◽

Vol 70 (4) ◽

pp. 2440-2448 ◽

Cited By ~ 9

Author(s):

Miia Pasanen ◽

Malgorzata Waleron ◽

Thomas Schott ◽

Ilse Cleenwerck ◽

Agnieszka Misztak ◽

...

Keyword(s):

Type Iii Secretion ◽

Type Strain ◽

Type Species ◽

Soft Rot ◽

Virulence Determinants ◽

Content Type ◽

Type Iii ◽

Link Type ◽

Core Proteins ◽

Genome Comparisons

Pectobacterium strains isolated from potato stems in Finland, Poland and the Netherlands were subjected to polyphasic analyses to characterize their genomic and phenotypic features. Phylogenetic analysis based on 382 core proteins showed that the isolates clustered closest to Pectobacterium polaris but could be divided into two clades. Average nucleotide identity (ANI) analysis revealed that the isolates in one of the clades included the P. polaris type strain, whereas the second clade was at the border of the species P. polaris with a 96 % ANI value. In silico genome-to-genome comparisons between the isolates revealed values below 70%, patristic distances based on 1294 core proteins were at the level observed between closely related Pectobacterium species, and the two groups of bacteria differed in genome size, G+C content and results of amplified fragment length polymorphism and Biolog analyses. Comparisons between the genomes revealed that the isolates of the atypical group contained SPI-1-type Type III secretion island and genes coding for proteins known for toxic effects on nematodes or insects, and lacked many genes coding for previously characterized virulence determinants affecting rotting of plant tissue by soft rot bacteria. Furthermore, the atypical isolates could be differentiated from P. polaris by their low virulence, production of antibacterial metabolites and a citrate-negative phenotype. Based on the results of a polyphasic approach including genome-to-genome comparisons, biochemical and virulence assays, presented in this report, we propose delineation of the atypical isolates as a novel species Pectobacterium parvum, for which the isolate s0421T (CFBP 8630T=LMG 30828T) is suggested as a type strain.

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Injectisome T3SS subunits as potential chaperones in the extracellular export of Pectobacterium carotovorum subsp. carotovorum bacteriocins Carocin S1 and Carocin S3 secreted via flagellar T3SS

BMC Microbiology ◽

10.1186/s12866-021-02405-w ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Huang-Pin Wu ◽

Reymund C. Derilo ◽

Han-Ling Chen ◽

Tzu-Rung Li ◽

Ruchi Briam James S. Lagitnay ◽

...

Keyword(s):

Type Iii Secretion ◽

Insertional Mutagenesis ◽

Plant Pathogens ◽

Soft Rot ◽

Economic Losses ◽

Pectobacterium Carotovorum ◽

Secretion Systems ◽

Unique Type ◽

Bacterial Flagellum ◽

Type Iii

AbstractPectobacterium carotovorum subsp. carotovorum (Pcc) causes soft-rot disease in a wide variety of plants resulting in economic losses worldwide. It produces various types of bacteriocin to compete against related plant pathogens. Studies on how bacteriocins are extracellularly secreted are conducted to understand the mechanism of interbacterial competition. In this study, the secretion of the low-molecular-weight bacteriocins (LMWB) Carocin S1 and Carocin S3 produced by a multiple-bacteriocin producing strain of Pcc, 89-H-4, was investigated. Tn5 insertional mutagenesis was used to generate a mutant, TH22–6, incapable of LMWBs secretion. Sequence and homology analyses of the gene disrupted by transposon Tn5 insertion revealed that the gene sctT, an essential component of the injectisome type III secretion machinery (T3aSS), is required for the secretion of the bacteriocins. This result raised a question regarding the nature of the secretion mechanism of Pcc bacteriocins which was previously discovered to be secreted via T3bSS, a system that utilizes the bacterial flagellum for extracellular secretions. Our previous report has shown that bacteriocin Carocin S1 cannot be secreted by mutants that are defective of T3bSS-related genes such as flhA, flhC, flhD and fliC. We knocked out several genes making up the significant structural components of both T3aSS and T3bSS. The findings led us to hypothesize the potential roles of the T3aSS-related proteins, SctT, SctU and SctV, as flagellar T3SS chaperones in the secretion of Pcc bacteriocins. This current discovery and the findings of our previous study helped us to conceptualize a unique Type III secretion system for bacteriocin extracellular export which is a hybrid of the injectisome and flagellar secretion systems.

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Assessing potato cultivars for resistance to tuber soft rot (Erwinia carotovora subsp.atroseptica) at four test centres in the UK

Potato Research ◽

10.1007/bf02360022 ◽

1988 ◽

Vol 31 (1) ◽

pp. 67-72 ◽

Cited By ~ 14

Author(s):

R. L. Wastie ◽

G. J. Jellis ◽

D. H. Lapwood ◽

C. Logan ◽

G. Little ◽

...

Keyword(s):

Erwinia Carotovora ◽

Soft Rot ◽

Potato Cultivars ◽

Erwinia Carotovora Subsp.Atroseptica ◽

The Uk ◽

Soft Rot Erwinia

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Bridging the Gap: Type III Secretion Systems in Plant-Beneficial Bacteria

Microorganisms ◽

10.3390/microorganisms10010187 ◽

2022 ◽

Vol 10 (1) ◽

pp. 187

Author(s):

Antoine Zboralski ◽

Adrien Biessy ◽

Martin Filion

Keyword(s):

Type Iii Secretion ◽

Plant Pathogens ◽

Plant Immunity ◽

Effector Proteins ◽

Secretion Systems ◽

Beneficial Bacteria ◽

Living Plant ◽

Pseudomonas Spp ◽

Type Iii ◽

Type Iii Secretion Systems

Type III secretion systems (T3SSs) are bacterial membrane-embedded nanomachines translocating effector proteins into the cytoplasm of eukaryotic cells. They have been intensively studied for their important roles in animal and plant bacterial diseases. Over the past two decades, genome sequencing has unveiled their ubiquitous distribution in many taxa of Gram-negative bacteria, including plant-beneficial ones. Here, we discuss the distribution and functions of the T3SS in two agronomically important bacterial groups: the symbiotic nodule-forming nitrogen-fixing rhizobia and the free-living plant-beneficial Pseudomonas spp. In legume-rhizobia symbiosis, T3SSs and their cognate effectors play important roles, including the modulation of the plant immune response and the initiation of the nodulation process in some cases. In plant-beneficial Pseudomonas spp., the roles of T3SSs are not fully understood, but pertain to plant immunity suppression, biocontrol against eukaryotic plant pathogens, mycorrhization facilitation, and possibly resistance against protist predation. The diversity of T3SSs in plant-beneficial bacteria points to their important roles in multifarious interkingdom interactions in the rhizosphere. We argue that the gap in research on T3SSs in plant-beneficial bacteria must be bridged to better understand bacteria/eukaryotes rhizosphere interactions and to support the development of efficient plant-growth promoting microbial inoculants.

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Concomitant Regulation by a LacI-Type Transcriptional Repressor XylR on Genes Involved in Xylan and Xylose Metabolism and the Type III Secretion System in Rice Pathogen Xanthomonas oryzae pv. oryzae

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-11-17-0277-r ◽

2018 ◽

Vol 31 (6) ◽

pp. 605-613 ◽

Cited By ~ 1

Author(s):

Yumi Ikawa ◽

Sayaka Ohnishi ◽

Akiko Shoji ◽

Ayako Furutani ◽

Seiji Tsuge

Keyword(s):

Gene Expression ◽

Type Iii Secretion ◽

Type Iii Secretion System ◽

Xylose Isomerase ◽

Secretion System ◽

Xanthomonas Oryzae ◽

Upstream Region ◽

Xylose Metabolism ◽

Type Iii ◽

Hrp Genes

The hypersensitive response and pathogenicity (hrp) genes of Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight of rice, encode components of the type III secretion system and are essential for virulence. Expression of hrp genes is regulated by two key hrp regulators, HrpG and HrpX; HrpG regulates hrpX and hrpA, and HrpX regulates the other hrp genes on hrpB-hrpF operons. We previously reported the sugar-dependent quantitative regulation of HrpX; the regulator highly accumulates in the presence of xylose, followed by high hrp gene expression. Here, we found that, in a mutant lacking the LacI-type transcriptional regulator XylR, HrpX accumulation and hrp gene expression were high even in the medium without xylose, reaching the similar levels present in the wild type incubated in the xylose-containing medium. XylR also negatively regulated one of two xylose isomerase genes (xylA2 but not xylA1) by binding to the motif sequence in the upstream region of the gene. Xylose isomerase is an essential enzyme in xylose metabolism and interconverts between xylose and xylulose. Our results suggest that, in the presence of xylose, inactivation of XylR leads to greater xylan and xylose utilization and, simultaneously, to higher accumulation of HrpX, followed by higher hrp gene expression in the bacterium.

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