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

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

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2001.14.8.962 ◽

2001 ◽

Vol 14 (8) ◽

pp. 962-968 ◽

Cited By ~ 56

Author(s):

A. Rantakari ◽

O. Virtaharju ◽

S. Vähämiko ◽

S. Taira ◽

E. T. Palva ◽

...

Keyword(s):

Gene Cluster ◽

Type Iii Secretion ◽

Plant Pathogens ◽

Erwinia Carotovora ◽

Soft Rot ◽

Hypersensitive Reaction ◽

Virulence Determinants ◽

Type Iii ◽

Hrp Genes ◽

Soft Rot Erwinia

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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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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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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