A complex composed of SycN and YscB functions as a specific chaperone for YopN in <i>Yersinia pestis</i>

Day, James B.; Plano, Gregory V.

doi:10.1046/j.1365-2958.1998.01110.x

Cited by 125 publications

(175 citation statements)

References 61 publications

(127 reference statements)

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“…Shown in Fig. 4, similar to the wild-type strain, the YP pnp strain ceased growing when shifted to 37°C in medium lacking calcium in contrast to YP strains with disregulated TTSSs that either constitutively secrete Yops in both the absence and presence of calcium termed calcium blind (22) or constitutively grow in either the presence or absence of calcium, calcium-independent. 2 These data indicate that PNPase is not required for TTSS-dependent growth restriction.…”

Section: Viability Of Pnpase and Various Ribonuclease-deficientmentioning

confidence: 76%

Modulation of Yersinia Type Three Secretion System by the S1 Domain of Polynucleotide Phosphorylase

Rosenzweig

Weltman

Plano

et al. 2005

Journal of Biological Chemistry

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120

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Both low temperatures and encounters with host phagocytes are two stresses that have been relatively well studied in many species of bacteria. Previous work has shown that the exoribonuclease polynucleotide phosphorylase (PNPase) is required for Yersiniae to grow at low temperatures. Here, we show that PNPase also enhances the ability of Yersinia pseudotuberculosis and Yersinia pestis to withstand the killing activities of murine macrophages. PNPase is required for the optimal functioning of the Yersinia type three secretion system (TTSS), an organelle that injects effector proteins directly into host cells. Unexpectedly, the effect of PNPase on the TTSS is independent of its ribonuclease activity and instead requires its S1 RNA binding domain. In contrast, catalytically inactive enzyme does not enhance the low temperature growth effect of PNPase. Surprisingly, wild-type-like TTSS functioning was restored to the pnp mutant strain by expressing just the ϳ70 amino acid S1 domains from either PNPase, RNase R, RNase II, or RpsA. Our findings suggest that PNPase plays multifaceted roles in enhancing Yersinia survival in response to stressful conditions.

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Section: Viability Of Pnpase and Various Ribonuclease-deficientmentioning

confidence: 76%

Modulation of Yersinia Type Three Secretion System by the S1 Domain of Polynucleotide Phosphorylase

Rosenzweig

Weltman

Plano

et al. 2005

Journal of Biological Chemistry

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120

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“…It has been difficult to study the role of chaperones in secretion of their cognate substrate, due to instability in the absence of the chaperone. YopH, YscM proteins, and YopN seem not to be secreted in the absence of their chaperone (Day and Plano, 1998;Cambronne et al, 2000), and thus a chaperone-dependent mechanism for secretion was proposed. For YopE, the first 15 amino acids were sufficient for secretion (but not translocation) of hybrid proteins in culture, whereas the first 50 amino acids (including both the transport signal as well as the SycE chaperone-binding site) were needed for translocation into the host cytosol suggesting a specific role for chaperones in translocation.…”

Section: Discussion the Role Of Chaperones In Secretionmentioning

confidence: 99%

Recognition of the Agrobacterium tumefaciens VirE2 Translocation Signal by the VirB/D4 Transport System Does Not Require VirE1

et al. 2003

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Agrobacterium tumefaciens uses a type IV secretion system to deliver a nucleoprotein complex and effector proteins directly into plant cells. The single-stranded DNA-binding protein VirE2, the F-box protein VirF and VirE3 are delivered into host cells via this VirB/D4 encoded translocation system. VirE1 functions as a chaperone of VirE2 by regulating its efficient translation and preventing VirE2-VirE2 aggregation in the bacterial cell. We analyzed whether the VirE1 chaperone is also essential for transport recognition of VirE2 by the VirB/D4 encoded type IV secretion system. In addition, we assayed whether translocation of VirF and VirE3, which also forms part of the virE operon, is affected by the absence of VirE1. We employed the earlier developed CRAFT (Cre recombinase Reporter Assay For Translocation) assay to detect transfer of Cre::Vir fusion proteins from A. tumefaciens into plants, monitored by stable reconstitution of a kanamycin resistance marker, and into yeast, screened by loss of the URA3 gene. We show that the C-terminal 50 amino acids of VirE2 and VirE3 are sufficient to mediate Cre translocation into host cells, confirming earlier indications of a C-terminal transport signal. This transfer was independent of the presence or absence of VirE1. Besides, the translocation efficiency of VirF is not altered in a virE1 mutant. The results unambiguously show that the VirE1 chaperone is not essential for the recognition of the VirE2 transport signal by the transport system and the subsequent translocation across the bacterial envelope into host cells.Agrobacterium tumefaciens causes crown gall disease on a wide range of plants by genetic transformation of host cells with a piece of its oncogenic plasmidborne transfer (T)-DNA (for most recent review, see Gelvin, 2003). The expression of the genes located on the T-DNA, which contain plant transcription and translation signals, results in overproduction of the plant hormones auxin and cytokinin and hence increased cell division and the tumor phenotype. A set of accessory virulence or effector proteins (encoded by the vir region on the tumor inducing [Ti] plasmid) is also transported into the transformed cells to confer full virulence. The host range is not confined to the plant kingdom, because A. tumefaciens can also transform yeast (Bundock et al., 1995), fungi (de Groot et al., 1998), and mammalian cells (Kunik et al., 2000).The translocated proteins of A. tumefaciens described to date include VirD2, VirE2, VirE3, and VirF. In the bacterium, VirD2 introduces a nick at the border sequences surrounding the T-DNA and by replacement synthesis a single-stranded (ss) DNA copy of the bottom strand is released. VirD2 acts as a pilot protein as it remains covalently attached to the 5Ј end of the T-strand during transport of the T-DNA into the host cell nucleus (Ward and Barnes, 1988). The ssDNA-binding protein VirE2 binds cooperatively to the T-strand and thereby protects it from degradation in the host cell (Rossi et al., 1996). Both VirD2 and VirE2 contain nucl...

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“…Strains mutated for any of these genes display de-repressed Yop expression and secretion in vitro, i.e. high levels of expression and secretion are seen, irrespective of the Ca 2+ concentration (Forsberg et al, 1991;Nilles et al, 1997;Day & Plano, 1998;Cheng & Schneewind, 2000;Matson & Nilles, 2001). Differing from the genus Yersinia, mutation in the pcrV gene of P. aeruginosa has been shown to result in constitutive secretion of type III effector molecules (Sawa et al, 1999;McCaw et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Factors triggering type III secretion in Pseudomonas aeruginosa

et al. 2005

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The type III secretion system of Pseudomonas aeruginosa is tightly regulated by various environmental signals, such as low calcium and contact with the host cell. However, the exact signals triggering type III secretion are unknown. The present study describes the finding that secretion of P. aeruginosa type III effector molecules requires protein factors from serum and L broth, designated type III secretion factors (TSFs), in addition to the low-calcium environment. In the absence of TSF or calcium chelator EGTA, basal levels of type III effector molecules are accumulated intracellularly. Addition of TSF and EGTA together effectively triggers the secretion of pre-existing effector molecules in a short time, even before the active expression of type III genes; thus, active type III gene expression does not seem to be a prerequisite for type III secretion. A search for TSF molecules in serum and L broth resulted in the identification of albumin and casein as the functional TSF molecules. Although there is no clear sequence similarity between albumin and casein, both proteins are known to have a low-affinity, high-capacity calcium-binding property. Tests of well-studied calcium-binding proteins seemed to indicate that low-affinity calcium-binding proteins have TSF activity, although the requirement of low-affinity calcium-binding ability for the TSF activity is not clear. P. aeruginosa seems to have evolved a sensing mechanism to detect target cells for type III injection through host-derived proteins in combination with a low-calcium signal. Disruption of the bacterial ability to sense low calcium or TSF might be a valid avenue to the effective control of this bacterial pathogen. INTRODUCTIONThe remarkable ability of Pseudomonas aeruginosa to adapt to and thrive in a wide variety of environments contributes significantly to the ability of this bacterium to cause various human infections (Bodey et al., 1983;Holder, 1993;Pier, 2002). Unlike most human pathogens possessing highly restricted host ranges, P. aeruginosa is pathogenic not only to humans, but also to Caenorhabditis elegans, Drosophila and Arabidopsis thaliana (Rahme et al., 1995;D'Argenio et al., 2001;Aballay & Ausubel, 2002). This broad host range is contributed in part by the numerous virulence factors encoded by P. aeruginosa, including exotoxin A, phospholipase C, alkaline protease, elastase, alginate, pyocyanin, pili and non-pilus adhesins (Ramphal et al., 1991;Deretic et al., 1995;Lory & Strom, 1997;Vasil & Ochsner, 1999). P. aeruginosa, like many other Gram-negative animal and plant pathogens, also encodes a type III secretion machinery, where over 30 proteins assemble into a complex designed to deliver effector molecules directly into the cytoplasmic compartment of eukaryotic cells (Yahr et al., 1995;Frank, 1997). Injection of the bacterial effector molecules into the host cells results in various physiological changes, all of which seem to confer a survival advantage on the bacterial pathogen within the host environment (Hueck, 1998;Muller et al...

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A complex composed of SycN and YscB functions as a specific chaperone for YopN in Yersinia pestis

Cited by 125 publications

References 61 publications

Modulation of Yersinia Type Three Secretion System by the S1 Domain of Polynucleotide Phosphorylase

Modulation of Yersinia Type Three Secretion System by the S1 Domain of Polynucleotide Phosphorylase

Recognition of the Agrobacterium tumefaciens VirE2 Translocation Signal by the VirB/D4 Transport System Does Not Require VirE1

Factors triggering type III secretion in Pseudomonas aeruginosa

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