scholarly journals Comparison of ATPase-Encoding Type III Secretion System hrcN Genes in Biocontrol Fluorescent Pseudomonads and in Phytopathogenic Proteobacteria

2004 ◽  
Vol 70 (9) ◽  
pp. 5119-5131 ◽  
Author(s):  
Fabio Rezzonico ◽  
Geneviève Défago ◽  
Yvan Moënne-Loccoz
Keyword(s):  
Pseudomonas Syringae ◽  
Protein Secretion ◽  
Type Iii Secretion ◽  
Fluorescent Pseudomonads ◽  
Secretion Systems ◽  
Associated Bacteria ◽  
Type Iii ◽  
Encoding Gene ◽  
Type Iii Protein Secretion ◽  
Protein Secretion Systems

ABSTRACT Type III protein secretion systems play a key role in the virulence of many pathogenic proteobacteria, but they also occur in nonpathogenic, plant-associated bacteria. Certain type III protein secretion genes (e.g., hrcC) have been found in Pseudomonas sp. strain SBW25 (and other biocontrol pseudomonads), but other type III protein secretion genes, such as the ATPase-encoding gene hrcN, have not been found. Using both colony hybridization and a PCR approach, we show here that hrcN is nevertheless present in many biocontrol fluorescent pseudomonads. The phylogeny of biocontrol Pseudomonas strains based on partial hrcN sequences was largely congruent with the phylogenies derived from analyses of rrs (encoding 16S rRNA) and, to a lesser extent, biocontrol genes, such as phlD (for 2,4-diacetylphloroglucinol production) and hcnBC (for HCN production). Most biocontrol pseudomonads clustered separately from phytopathogenic proteobacteria, including pathogenic pseudomonads, in the hrcN tree. The exception was strain KD, which clustered with phytopathogenic pseudomonads, such as Pseudomonas syringae, suggesting that hrcN was acquired from the latter species. Indeed, strain KD (unlike strain SBW25) displayed the same organization of the hrpJ operon, which contains hrcN, as P. syringae. These results indicate that the occurrence of hrcN in most biocontrol pseudomonads is not the result of recent horizontal gene transfer from phytopathogenic bacteria, although such transfer might have occurred for a minority of biocontrol strains.

scholarly journals Type III Protein Secretion Systems in Bacterial Pathogens of Animals and Plants

1998 ◽  
Vol 62 (2) ◽  
pp. 379-433 ◽  
Author(s):  
Christoph J. Hueck
Keyword(s):  
Host Cell ◽  
Protein Secretion ◽  
Type Iii Secretion ◽  
Plant Pathogens ◽  
Host Cells ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Animal Pathogens ◽  
Type Iii Protein Secretion

SUMMARY Various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. It is becoming increasingly clear that these so-called type III secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. Accordingly, some type III secretion systems are activated by bacterial contact with host cell surfaces. Individual type III secretion systems direct the secretion and translocation of a variety of unrelated proteins, which account for species-specific pathogenesis phenotypes. In contrast to the secreted virulence factors, most of the 15 to 20 membrane-associated proteins which constitute the type III secretion apparatus are conserved among different pathogens. Most of the inner membrane components of the type III secretion apparatus show additional homologies to flagellar biosynthetic proteins, while a conserved outer membrane factor is similar to secretins from type II and other secretion pathways. Structurally conserved chaperones which specifically bind to individual secreted proteins play an important role in type III protein secretion, apparently by preventing premature interactions of the secreted factors with other proteins. The genes encoding type III secretion systems are clustered, and various pieces of evidence suggest that these systems have been acquired by horizontal genetic transfer during evolution. Expression of type III secretion systems is coordinately regulated in response to host environmental stimuli by networks of transcription factors. This review comprises a comparison of the structure, function, regulation, and impact on host cells of the type III secretion systems in the animal pathogens Yersinia spp., Pseudomonas aeruginosa, Shigella flexneri, Salmonella typhimurium, enteropathogenic Escherichia coli, and Chlamydia spp. and the plant pathogens Pseudomonas syringae, Erwinia spp., Ralstonia solanacearum, Xanthomonas campestris, and Rhizobium spp.

scholarly journals A protein secreted by the Salmonella type III secretion system controls needle filament assembly

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Junya Kato ◽  
Supratim Dey ◽  
Jose E Soto ◽  
Carmen Butan ◽  
Mason C Wilkinson ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Central Component ◽  
Secretion Systems ◽  
Type Iii ◽  
Capping Proteins ◽  
Filament Assembly ◽  
Exogenous Addition ◽  
Type Iii Protein Secretion ◽  
Protein Secretion Systems

Type III protein secretion systems (T3SS) are encoded by several pathogenic or symbiotic bacteria. The central component of this nanomachine is the needle complex. Here we show in a Salmonella Typhimurium T3SS that assembly of the needle filament of this structure requires OrgC, a protein encoded within the T3SS gene cluster. Absence of OrgC results in significantly reduced number of needle substructures but does not affect needle length. We show that OrgC is secreted by the T3SS and that exogenous addition of OrgC can complement a ∆orgC mutation. We also show that OrgC interacts with the needle filament subunit PrgI and accelerates its polymerization into filaments in vitro. The structure of OrgC shows a novel fold with a shared topology with a domain from flagellar capping proteins. These findings identify a novel component of T3SS and provide new insight into the assembly of the type III secretion machine.

scholarly journals YplA Is Exported by the Ysc, Ysa, and Flagellar Type III Secretion Systems of Yersinia enterocolitica

2002 ◽  
Vol 184 (5) ◽  
pp. 1324-1334 ◽  
Author(s):  
Briana M. Young ◽  
Glenn M. Young
Keyword(s):  
Yersinia Enterocolitica ◽  
Protein Secretion ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Chloride Concentration ◽  
Effector Proteins ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Type Iii Protein Secretion

ABSTRACT Yersinia enterocolitica maintains three different pathways for type III protein secretion. Each pathway requires the activity of a specific multicomponent apparatus or type III secretion system (TTSS). Two of the TTSSs are categorized as contact-dependent systems which have been shown in a number of different symbiotic and pathogenic bacteria to influence interactions with host organisms by targeting effector proteins into the cytosol of eukaryotic cells. The third TTSS is required for the assembly of flagella and the secretion of the phospholipase YplA, which has been implicated in Y. enterocolitica virulence. In this study, YplA was expressed from a constitutive promoter in strains that contained only a single TTSS. It was determined that each of the three TTSSs is individually sufficient for YplA secretion. Environmental factors such as temperature, calcium availability, and sodium chloride concentration affected the contribution of each system to extracellular protein secretion and, under some conditions, more than one TTSS appeared to operate simultaneously. This suggests that some proteins might normally be exported by more than one TTSS in Y. enterocolitca.

scholarly journals A NanoLuc luciferase-based assay enabling the real-time analysis of protein secretion and injection by bacterial type III secretion systems

2019 ◽  
Author(s):  
Sibel Westerhausen ◽  
Melanie Nowak ◽  
Claudia Torres-Vargas ◽  
Ursula Bilitewski ◽  
Erwin Bohn ◽  
...  
Keyword(s):  
Protein Secretion ◽  
High Throughput ◽  
Type Iii Secretion ◽  
Molecular Mechanisms ◽  
Host Cells ◽  
Target Cells ◽  
Secretion Systems ◽  
Type Iii ◽  
Nanoluc Luciferase ◽  
Type Iii Secretion Systems

AbstractThe elucidation of the molecular mechanisms of secretion through bacterial protein secretion systems is impeded by a lack of assays to quantitatively assess secretion kinetics. Also the analysis of the biological role of these secretion systems as well as the identification of inhibitors targeting these systems would greatly benefit from the availability of a simple, quick and quantitative assay to monitor principle secretion and injection into host cells. Here we present a versatile solution to this need, utilizing the small and very bright NanoLuc luciferase to assess secretion and injection through the type III secretion system encoded by Salmonella pathogenicity island 1. The NanoLuc-based secretion assay features a very high signal-to-noise ratio and sensitivity down to the nanoliter scale. The assay enables monitoring of secretion kinetics and is adaptable to a high throughput screening format in 384-well microplates. We further developed NanoLuc and split-NanoLuc-based assays that enable the monitoring of type III secretion-dependent injection of effector proteins into host cells.ImportanceThe ability to secrete proteins to the bacterial cell surface, to the extracellular environment, or even into target cells is one of the foundations of interbacterial as well as pathogen-host interaction. While great progress has been made in elucidating assembly and structure of secretion systems, our understanding of their secretion mechanism often lags behind, not last because of the challenge to quantitatively assess secretion function. Here, we developed a luciferase-based assay to enable the simple, quick, quantitative, and high throughput-compatible assessment of secretion and injection through virulence-associated type III secretion systems. The assay allows detection of minute amounts of secreted substrate proteins either in the supernatant of the bacterial culture or within eukaryotic host cells. It thus provides an enabling technology to elucidate the mechanisms of secretion and injection of type III secretion systems and is likely adaptable to assay secretion through other bacterial secretion systems.

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