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 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 Identification of a Specific Chaperone for SptP, a Substrate of the Centisome 63 Type III Secretion System ofSalmonella typhimurium

1998 ◽  
Vol 180 (13) ◽  
pp. 3393-3399 ◽  
Author(s):  
Yixin Fu ◽  
Jorge E. Galán
Keyword(s):  
Actin Cytoskeleton ◽  
Host Cell ◽  
Type Iii Secretion ◽  
Tyrosine Phosphatase ◽  
Secretion System ◽  
Effector Proteins ◽  
Loss Of Function ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Protein Secretion

ABSTRACT Salmonella typhimurium uses of a type III protein secretion system encoded at centisome 63 of its chromosome to deliver effector molecules into the host cell. These proteins stimulate host cell responses such as reorganization of the actin cytoskeleton and activation of transcription factors. One of these effector proteins is SptP, a tyrosine phosphatase that causes disruption of the host cell actin cytoskeleton. A characteristic feature of many substrates of type III secretion systems is their association with specific cytoplasmic chaperones which appears to be required for secretion and/or translocation of these proteins into the host cell. We report here the identification of SicP, a 13-kDa acidic polypeptide that is encoded immediately upstream of sptP. A loss-of-function mutation in sicP resulted in drastically reduced levels of SptP but did not affect sptP expression, indicating that SicP exerts its effect posttranscriptionally. Pulse-chase experiments demonstrated that the loss of SicP leads to increased degradation of SptP. In addition, we show that SicP binds to SptP directly and that the binding site is located between residues 15 and 100 of the tyrosine phosphatase. Taken together, these results indicate that SicP acts as a specific chaperone for SptP.

scholarly journals Antibodies Inhibiting the Type III Secretion System of Gram-Negative Pathogenic Bacteria

Antibodies ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 35
Author(s):  
Julia A. Hotinger ◽  
Aaron E. May
Keyword(s):  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Type Iii Secretion System ◽  
The United States ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Gram Negative ◽  
Type Iii ◽  
Shigella Spp

Pathogenic bacteria are a global health threat, with over 2 million infections caused by Gram-negative bacteria every year in the United States. This problem is exacerbated by the increase in resistance to common antibiotics that are routinely used to treat these infections, creating an urgent need for innovative ways to treat and prevent virulence caused by these pathogens. Many Gram-negative pathogenic bacteria use a type III secretion system (T3SS) to inject toxins and other effector proteins directly into host cells. The T3SS has become a popular anti-virulence target because it is required for pathogenesis and knockouts have attenuated virulence. It is also not required for survival, which should result in less selective pressure for resistance formation against T3SS inhibitors. In this review, we will highlight selected examples of direct antibody immunizations and the use of antibodies in immunotherapy treatments that target the bacterial T3SS. These examples include antibodies targeting the T3SS of Pseudomonas aeruginosa, Yersinia pestis, Escherichia coli, Salmonella enterica, Shigella spp., and Chlamydia trachomatis.

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 The Type III Secretion System of Bradyrhizobium japonicum USDA122 Mediates Symbiotic Incompatibility withRj2Soybean Plants

2012 ◽  
Vol 79 (3) ◽  
pp. 1048-1051 ◽  
Author(s):  
Takahiro Tsukui ◽  
Shima Eda ◽  
Takakazu Kaneko ◽  
Shusei Sato ◽  
Shin Okazaki ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Bradyrhizobium Japonicum ◽  
Secretion System ◽  
Effector Proteins ◽  
Wild Type ◽  
Content Type ◽  
Type Iii ◽  
Protein Secretion System ◽  
Soybean Plants ◽  
Type Iii Protein Secretion

ABSTRACTTherhcJandttsImutants ofBradyrhizobium japonicumUSDA122 for the type III protein secretion system (T3SS) failed to secrete typical effector proteins and gained the ability to nodulateRj2soybean plants (Hardee), which are symbiotically incompatible with wild-type USDA122. This suggests that effectors secreted via the T3SS trigger incompatibility between these two partners.

scholarly journals Molecular Targets and Strategies for Inhibition of the Bacterial Type III Secretion System (T3SS); Inhibitors Directly Binding to T3SS Components

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 316 ◽  
Author(s):  
Julia A. Hotinger ◽  
Heather A. Pendergrass ◽  
Aaron E. May
Keyword(s):  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Type Iii Secretion System ◽  
Systemic Infection ◽  
Inhibitory Effect ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Complex Nature ◽  
Type Iii

The type III secretion system (T3SS) is a virulence apparatus used by many Gram-negative pathogenic bacteria to cause infections. Pathogens utilizing a T3SS are responsible for millions of infections yearly. Since many T3SS knockout strains are incapable of causing systemic infection, the T3SS has emerged as an attractive anti-virulence target for therapeutic design. The T3SS is a multiprotein molecular syringe that enables pathogens to inject effector proteins into host cells. These effectors modify host cell mechanisms in a variety of ways beneficial to the pathogen. Due to the T3SS’s complex nature, there are numerous ways in which it can be targeted. This review will be focused on the direct targeting of components of the T3SS, including the needle, translocon, basal body, sorting platform, and effector proteins. Inhibitors will be considered a direct inhibitor if they have a binding partner that is a T3SS component, regardless of the inhibitory effect being structural or functional.

scholarly journals Identification of novel Ralstonia solanacearum type III effector proteins through translocation analysis of hrpB-regulated gene products

Microbiology ◽  
2009 ◽  
Vol 155 (7) ◽  
pp. 2235-2244 ◽  
Author(s):  
Takafumi Mukaihara ◽  
Naoyuki Tamura
Keyword(s):  
Ralstonia Solanacearum ◽  
Pathogenic Bacteria ◽  
Tandem Repeats ◽  
Plant Cells ◽  
Secretion System ◽  
Effector Proteins ◽  
Gene Products ◽  
Type Iii Effector ◽  
Type Iii ◽  
Effector Genes

The Hrp type III secretion system (TTSS) is essential for the pathogenicity of Ralstonia solanacearum on host plants. Hrp TTSS is a specialized secretion system that injects virulence proteins, the so-called type III effector proteins, into plant cells. In R. solanacearum, the expression of Hrp TTSS-related genes is regulated by an AraC-type transcriptional activator, HrpB. We have identified 30 hrpB-regulated hpx ( hrpB-dependent expression) genes and three well-known hrpB-regulated genes, popA, popB and popC, as candidate effector genes in R. solanacearum strain RS1000. In this study, we newly cloned 11 additional candidate effector genes that share homology with known hpx genes from R. solanacearum RS1000. Using a Cya reporter system, we investigated the translocation of these 44 gene products into plant cells via the Hrp TTSS and identified 34 effector proteins. These include three effector families composed of more than four members, namely the Hpx4, Hpx30 and GALA families. The Hpx30 family effectors are 2200–2500 aa in size and appear to be the largest class of effector proteins among animal- and plant-pathogenic bacteria. Members of this family contain 12–18 tandem repeats of a novel 42 aa motif, designated SKWP repeats.

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.

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