scholarly journals PopF1 and PopF2, Two Proteins Secreted by the Type III Protein Secretion System of Ralstonia solanacearum, Are Translocators Belonging to the HrpF/NopX Family

2006 ◽  
Vol 188 (13) ◽  
pp. 4903-4917 ◽  
Author(s):  
Damien Meyer ◽  
Sébastien Cunnac ◽  
Mareva Guéneron ◽  
Céline Declercq ◽  
Frédérique Van Gijsegem ◽  
...  
Keyword(s):  
Protein Secretion ◽  
Ralstonia Solanacearum ◽  
Xanthomonas Campestris ◽  
Pathogenic Bacteria ◽  
Secretion System ◽  
Effector Proteins ◽  
Experimental Conditions ◽  
Type Iii ◽  
Protein Secretion System ◽  
Type Iii Protein Secretion

ABSTRACT Ralstonia solanacearum GMI1000 is a gram-negative plant pathogen which contains an hrp gene cluster which codes for a type III protein secretion system (TTSS). We identified two novel Hrp-secreted proteins, called PopF1 and PopF2, which display similarity to one another and to putative TTSS translocators, HrpF and NopX, from Xanthomonas spp. and rhizobia, respectively. They also show similarities with TTSS translocators of the YopB family from animal-pathogenic bacteria. Both popF1 and popF2 belong to the HrpB regulon and are required for the interaction with plants, but PopF1 seems to play a more important role in virulence and hypersensitive response (HR) elicitation than PopF2 under our experimental conditions. PopF1 and PopF2 are not necessary for the secretion of effector proteins, but they are required for the translocation of AvrA avirulence protein into tobacco cells. We conclude that PopF1 and PopF2 are type III translocators belonging to the HrpF/NopX family. The hrpF gene of Xanthomonas campestris pv. campestris partially restored HR-inducing ability to popF1 popF2 mutants of R. solanacearum, suggesting that translocators of R. solanacearum and Xanthomonas are functionally conserved. Finally, R. solanacearum strain UW551, which does not belong to the same phylotype as GMI1000, also possesses two putative translocator proteins. However, although one of these proteins is clearly related to PopF1 and PopF2, the other seems to be different and related to NopX proteins, thus showing that translocators might be variable in R. solanacearum.

scholarly journals The Pseudomonas syringae HopPtoV Protein Is Secreted in Culture and Translocated into Plant Cells via the Type III Protein Secretion System in a Manner Dependent on the ShcV Type III Chaperone

2004 ◽  
Vol 186 (11) ◽  
pp. 3621-3630 ◽  
Author(s):  
Misty D. Wehling ◽  
Ming Guo ◽  
Zheng Qing Fu ◽  
James R. Alfano
Keyword(s):  
Pseudomonas Syringae ◽  
Protein Secretion ◽  
Plant Cells ◽  
Secretion System ◽  
Effector Proteins ◽  
In Planta ◽  
Type Iii ◽  
Protein Secretion System ◽  
Type Iii Protein Secretion ◽  
Plant Pathogenesis

ABSTRACT The bacterial plant pathogen Pseudomonas syringae depends on a type III protein secretion system and the effector proteins that it translocates into plant cells to cause disease and to elicit the defense-associated hypersensitive response on resistant plants. The availability of the P. syringae pv. tomato DC3000 genome sequence has resulted in the identification of many novel effectors. We identified the hopPtoV effector gene on the basis of its location next to a candidate type III chaperone (TTC) gene, shcV, and within a pathogenicity island in the DC3000 chromosome. A DC3000 mutant lacking ShcV was unable to secrete detectable amounts of HopPtoV into culture supernatants or translocate HopPtoV into plant cells, based on an assay that tested whether HopPtoV-AvrRpt2 fusions were delivered into plant cells. Coimmunoprecipitation and Saccharomyces cerevisiae two-hybrid experiments showed that ShcV and HopPtoV interact directly with each other. The ShcV binding site was delimited to an N-terminal region of HopPtoV between amino acids 76 and 125 of the 391-residue full-length protein. Our results demonstrate that ShcV is a TTC for the HopPtoV effector. DC3000 overexpressing ShcV and HopPtoV and DC3000 mutants lacking either HopPtoV or both ShcV and HopPtoV were not significantly impaired in disease symptoms or bacterial multiplication in planta, suggesting that HopPtoV plays a subtle role in pathogenesis or that other effectors effectively mask the contribution of HopPtoV in plant pathogenesis.

scholarly journals ClpXP Protease Controls Expression of the Type III Protein Secretion System through Regulation of RpoS and GrlR Levels in Enterohemorrhagic Escherichia coli

2005 ◽  
Vol 187 (12) ◽  
pp. 4086-4094 ◽  
Author(s):  
Sunao Iyoda ◽  
Haruo Watanabe
Keyword(s):  
Escherichia Coli ◽  
Protein Secretion ◽  
Deletion Mutant ◽  
Regulatory Gene ◽  
Secretion System ◽  
Enterohemorrhagic Escherichia Coli ◽  
Multicopy Plasmid ◽  
Type Iii ◽  
Protein Secretion System ◽  
Type Iii Protein Secretion

ABSTRACT Expression of the type III protein secretion system (TTSS), encoded in the locus of enterocyte effacement (LEE) of enterohemorrhagic Escherichia coli (EHEC), has been shown to be controlled by various regulators. In a search for additional regulatory genes, we identified a DNA fragment containing clpX and clpP that has a positive regulatory effect on LEE expression in EHEC O157. The expression of LEE-encoded Esp proteins was significantly reduced in a clpXP deletion mutant. Deletion of grlR, a negative regulatory gene within LEE, markedly increased LEE expression even in the clpXP mutant. To verify the regulatory mechanism of GrlR expression, a chromosomal epitope-tagged allele of grlR (grlR-FLAG) was constructed. GrlR-FLAG expression was increased significantly in the clpXP deletion mutant, suggesting that the GrlR level is under the control of ClpXP, and this regulation is critical for the ClpXP-dependent expression of LEE in EHEC. Deletion of rpoS, the gene encoding a stationary-phase-inducing sigma factor that is a substrate for ClpXP protease, partially restored LEE expression in the clpXP mutant. A multicopy plasmid carrying rpoS strongly repressed expression of Esp proteins, suggesting that positive regulation by ClpXP is partially mediated through a negative effect of RpoS on LEE expression. We also found that rpoS deletion induces transcription of pchA, which encodes one of the positive regulators for LEE expression in EHEC. These results suggest that ClpXP controls expression of LEE through the regulation of RpoS and GrlR levels in EHEC.

scholarly journals Extracellular Proteins Involved in Soybean Cultivar-Specific Nodulation Are Associated with Pilus-Like Surface Appendages and Exported by a Type III Protein Secretion System in Sinorhizobium fredii USDA257

2003 ◽  
Vol 16 (7) ◽  
pp. 617-625 ◽  
Author(s):  
Hari B. Krishnan ◽  
Julio Lorio ◽  
Won Seok Kim ◽  
Guoqiao Jiang ◽  
Kil Yong Kim ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Symbiotic Bacterium ◽  
Secretion System ◽  
Extracellular Proteins ◽  
Effector Proteins ◽  
Broad Host Range ◽  
Sinorhizobium Fredii ◽  
Type Iii ◽  
Conserved Genes ◽  
Type Iii Protein Secretion

Several gram-negative plant and animal pathogenic bacteria have evolved a type III secretion system (TTSS) to deliver effector proteins directly into the host cell cytosol. Sinorhizobium fredii USDA257, a symbiont of soybean and many other legumes, secretes proteins called Nops (nodulation outer proteins) into the extracellular environment upon flavonoid induction. Mutation analysis and the nucleotide sequence of a 31.2-kb symbiosis (sym) plasmid DNA region of USDA257 revealed the existence of a TTSS locus in this symbiotic bacterium. This locus includes rhc (rhizobia conserved) genes that encode components of a TTSS and proteins that are secreted into the environment (Nops). The genomic organization of the TTSS locus of USDA257 is remarkably similar to that of another broad-host range symbiont, Rhizobium sp. strain NGR234. Flavonoids that activate the transcription of the nod genes of USDA257 also stimulate the production of novel filamentous appendages known as pili. Electron microscope examination of isolated pili reveals needle-like filaments of 6 to 8 nm in diameter. The production of the pili is dependent on a functional nodD1 and the presence of a nod gene-inducing compound. Mutations in several of the TTSS genes negate the ability of USDA257 to elaborate pili. Western blot analysis using antibodies raised against purified NopX, Nop38, and Nop7 reveals that these proteins were associated with the pili. Mutations in rhcN, rhcJ, rhcC, and ttsI alter the ability of USDA257 to form nodules on Glycine max and Macroptilium atropurpureum.

scholarly journals The type III protein secretion system contributes to Xanthomonas citri subsp. citri biofilm formation

2014 ◽  
Vol 14 (1) ◽  
pp. 96 ◽  
Author(s):  
Tamara Zimaro ◽  
Ludivine Thomas ◽  
Claudius Marondedze ◽  
Germán G Sgro ◽  
Cecilia G Garofalo ◽  
...  
Keyword(s):  
Protein Secretion ◽  
Biofilm Formation ◽  
Secretion System ◽  
Xanthomonas Citri ◽  
Type Iii ◽  
Protein Secretion System ◽  
Type Iii Protein Secretion
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