scholarly journals Biogenesis of the Fraction 1 Capsule and Analysis of the Ultrastructure of Yersinia pestis

2008 ◽  
Vol 190 (9) ◽  
pp. 3381-3385 ◽  
Author(s):  
Lisa M. Runco ◽  
Selina Myrczek ◽  
James B. Bliska ◽  
David G. Thanassi
Keyword(s):  
Yersinia Pestis ◽  
Host Recognition ◽  
Surface Features ◽  
Bacterial Surface

ABSTRACT Analysis of a Yersinia pestis Δcaf1A mutant demonstrated that the Caf1A usher is required for the assembly and secretion of the fraction 1 capsule. The capsule assembled into thin fibrils and denser aggregates on the bacterial surface. Pilus-like fibers were also detected on the surface of Y. pestis. The capsule occasionally coated these fibers, suggesting how the capsule may cloak surface features to prevent host recognition.

scholarly journals Proteolytic processing of the Yersinia pestis YapG autotransporter by the omptin protease Pla and the contribution of YapG to murine plague pathogenesis

2013 ◽  
Vol 62 (8) ◽  
pp. 1124-1134 ◽  
Author(s):  
M. Chelsea Lane ◽  
Jonathan D. Lenz ◽  
Virginia L. Miller
Keyword(s):  
Yersinia Pestis ◽  
Mouse Models ◽  
Yersinia Pseudotuberculosis ◽  
Proteolytic Processing ◽  
Complex Life Cycle ◽  
Bacterial Surface ◽  
Bacterial Membranes ◽  
Gastrointestinal Pathogen ◽  
Wide Range ◽  
Associated Functions

Autotransporter protein secretion represents one of the simplest forms of secretion across Gram-negative bacterial membranes. Once secreted, autotransporter proteins either remain tethered to the bacterial surface or are released following proteolytic cleavage. Autotransporters possess a diverse array of virulence-associated functions such as motility, cytotoxicity, adherence and autoaggregation. To better understand the role of autotransporters in disease, our research focused on the autotransporters of Yersinia pestis, the aetiological agent of plague. Y. pestis strain CO92 has nine functional conventional autotransporters, referred to as Yaps for Yersinia autotransporter proteins. Three Yaps have been directly implicated in virulence using established mouse models of plague infection (YapE, YapJ and YapK). Whilst previous studies from our laboratory have shown that most of the CO92 Yaps are cell associated, YapE and YapG are processed and released by the omptin protease Pla. In this study, we identified the Pla cleavage sites in YapG that result in many released forms of YapG in Y. pestis, but not in the evolutionarily related gastrointestinal pathogen, Yersinia pseudotuberculosis, which lacks Pla. Furthermore, we showed that YapG does not contribute to Y. pestis virulence in established mouse models of bubonic and pneumonic infection. As Y. pestis has a complex life cycle involving a wide range of mammalian hosts and a flea vector for transmission, it remains to be elucidated whether YapG has a measurable role in any other stage of plague disease.

scholarly journals LcrV of Yersinia pestis Enters Infected Eukaryotic Cells by a Virulence Plasmid-Independent Mechanism

1999 ◽  
Vol 67 (9) ◽  
pp. 4801-4813 ◽  
Author(s):  
Kenneth A. Fields ◽  
Susan C. Straley
Keyword(s):  
Yersinia Pestis ◽  
Laser Scanning ◽  
Surrounding Medium ◽  
Immunoblot Analysis ◽  
Laser Scanning Confocal Microscopy ◽  
Eukaryotic Cells ◽  
Infection Model ◽  
Virulence Plasmid ◽  
Bacterial Surface ◽  
Scanning Confocal Microscopy

ABSTRACT Yersinia pestis is the causative agent of bubonic plague and possesses a set of plasmid-encoded, secretable virulence proteins termed LcrV and Yops which are essential for survival in mammalian hosts. Yops and LcrV are secreted by a type III mechanism (Ysc), and Yops are unidirectionally targeted into the cytosol of associated eukaryotic cells in a tissue culture infection model. LcrV is required for Yops targeting, and recent findings have revealed that it can localize to the bacterial surface; however, its fate in this infection model has not been investigated in detail. In this study, we compared the localization of LcrV to that of the targeted proteins YopE and YopM by immunoblot analysis of fractions ofYersinia-infected HeLa cultures or by laser-scanning confocal microscopy of infected monolayers. Both LcrV and YopE were secreted by contact-activated, extracellularly localized yersiniae and were targeted to the HeLa cell cytosol. Although a significant amount of LcrV partitioned to the culture medium (unlike YopE), this extracellular pool of LcrV was not the source of the LcrV that entered HeLa cells. Unlike targeting of YopE and YopM, targeting of LcrV occurred in the absence of a functional Ysc apparatus and other virulence plasmid (pCD1)-expressed proteins. However, the Ysc is necessary for LcrV to be released into the medium, and our recent work has shown that localization of LcrV on the bacterial surface requires the Ysc. These results indicate that two mechanisms exist for the secretion of LcrV by Y. pestis, both of which are activated by contact with eukaryotic cells. LcrV secreted by the Ysc reaches the bacterial surface and the surrounding medium, whereas the second is a novel, Ysc-independent pathway which results in localization of LcrV in the cytosol of infected cells but not the surrounding medium.

scholarly journals YscP of Yersinia pestis Is a Secreted Component of the Yop Secretion System

1999 ◽  
Vol 181 (9) ◽  
pp. 2852-2862 ◽  
Author(s):  
Patricia L. Payne ◽  
Susan C. Straley
Keyword(s):  
Amino Acids ◽  
Yersinia Pestis ◽  
Secretion System ◽  
Mutant Protein ◽  
Adjacent Gene ◽  
Core Component ◽  
Bacterial Surface ◽  
Regulated Expression ◽  
V Antigen

ABSTRACT The Yersinia pestis low-Ca2+ response stimulon is responsible for the environmentally regulated expression and secretion of antihost proteins (V antigen and Yops). We have previously shown that yscO encodes a secreted core component of the Yop secretion (Ysc) mechanism. In this study, we constructed and characterized in-frame deletions in the adjacent gene,yscP, in the yscN–yscU operon. The ΔP1 mutation, which removed amino acids 246 to 333 of YscP, had no effect on Yop expression or secretion, and the mutant protein, YscP1, was secreted, as was YscP in the parent. In contrast, the ΔP2 strain expressed and secreted less of each Yop than did the parent under the inductive conditions of 37°C and the absence of Ca2+, with an exception being YopE, which was only minimally affected by the mutation. The YscP2 protein, missing amino acids 57 to 324 of YscP, was expressed but not secreted by the ΔP2 mutant. The effect of the ΔP2 mutation was at the level of Yop secretion because YopM and V antigen still showed limited secretion when overproduced in trans. Excess YscP also affected secretion: overexpression of YscP in the parent, in either yscP mutant, or in an lcrGmutant effectively shut off secretion. However, co-overexpression of YscO and YscP had no effect on secretion, and YscP overexpression in anlcrE mutant had little effect on Yop secretion, suggesting that YscP acts, in conjunction with YscO, at the level of secretion control of LcrE at the bacterial surface. These findings place YscP among the growing family of mobile Ysc components that both affect secretion and themselves are secreted by the Ysc.

scholarly journals Virulence Role of V Antigen of Yersinia pestis at the Bacterial Surface

1999 ◽  
Vol 67 (10) ◽  
pp. 5395-5408 ◽  
Author(s):  
Kenneth A. Fields ◽  
Matthew L. Nilles ◽  
Clarissa Cowan ◽  
Susan C. Straley
Keyword(s):  
Yersinia Pestis ◽  
Laser Scanning ◽  
Protective Efficacy ◽  
Laser Scanning Confocal Microscopy ◽  
Etiologic Agent ◽  
Multifunctional Protein ◽  
Bacterial Surface ◽  
Scanning Confocal Microscopy ◽  
Facilitative Role ◽  
V Antigen

ABSTRACT Yersinia pestis, the etiologic agent of plague, secretes a set of environmentally regulated, plasmid pCD1-encoded virulence proteins termed Yops and V antigen (LcrV) by a type III secretion mechanism (Ysc). LcrV is a multifunctional protein that has been shown to act at the level of secretion control by binding the Ysc inner-gate protein LcrG and to modulate the host immune response by altering cytokine production. LcrV also is essential for the unidirectional targeting of Yops to the cytosol of infected eukaryotic cells. In this study, we constructed an in-frame deletion withinlcrG (ΔlcrG3) to further analyze the requirement of LcrV in Yop targeting. We confirmed the essentiality of LcrV and found that LcrG may have a facilitative role, perhaps by promoting efficient secretion of LcrV. We also constructed mutants oflcrV expressing LcrV truncated at the N or C terminus. Both the N and C termini of LcrV were required for the secretion of LcrV into the medium and targeting of Yops. LcrV was detected in punctate zones on the surface of fixed Y. pestis by laser-scanning confocal microscopy, and this localization required a functional Ysc. However, the truncated LcrV proteins were not found on the bacterial surface. Finally, we tested the ability of LcrV-specific Fab antibody fragments or full-length antibody to interfere with Yop targeting and found no interference, even though this antibody protects mice against plague. These results indicate that LcrV may function in Yop targeting at the extracellular surface of yersiniae and that the protective efficacy of LcrV-specific antibodies can be manifested without blocking Yop targeting.

Evaluation of whole cell fixation methods for the analysis of nanoscale surface features of Yersinia pestis KIM

2016 ◽  
Vol 263 (3) ◽  
pp. 260-267 ◽  
Author(s):  
C. WANG ◽  
C.E. STANCIU ◽  
C.J. EHRHARDT ◽  
V.K. YADAVALLI
Keyword(s):  
Yersinia Pestis ◽  
Whole Cell ◽  
Surface Features ◽  
Fixation Methods ◽  
Cell Fixation

scholarly journals Role of Fraction 1 Antigen of Yersinia pestis in Inhibition of Phagocytosis

2002 ◽  
Vol 70 (3) ◽  
pp. 1453-1460 ◽  
Author(s):  
Yidong Du ◽  
Roland Rosqvist ◽  
Åke Forsberg
Keyword(s):  
Yersinia Pestis ◽  
Effector Proteins ◽  
Receptor Interaction ◽  
Virulence Plasmid ◽  
Protein Subunit ◽  
Bacterial Surface ◽  
Type Iii ◽  
F1 Antigen ◽  
J774 Cells

ABSTRACT Yersinia pestis, the causative agent of plague, expresses a capsule-like antigen, fraction 1 (F1), at 37°C. F1 is encoded by the caf1 gene located on the large 100-kb pFra plasmid, which is unique to Y. pestis. F1 is a surface polymer composed of a protein subunit, Caf1, with a molecular mass of 15.5 kDa. The secretion and assembly of F1 require the caf1M and caf1A genes, which are homologous to the chaperone and usher protein families required for biogenesis of pili. F1 has been implicated to be involved in the ability of Y. pestis to prevent uptake by macrophages. In this study we addressed the role of F1 antigen in inhibition of phagocytosis by the macrophage-like cell line J774. The Y. pestis strain EV76 was found to be highly resistant to uptake by J774 cells. An in-frame deletion of the caf1M gene of the Y. pestis strain EV76 was constructed and found to be unable to express F1 polymer on the bacterial surface. This strain had a somewhat lowered ability to prevent uptake by J774 cells. Strain EV76C, which is cured for the virulence plasmid common to the pathogenic Yersinia species, was, as expected, much reduced in its ability to resist uptake. A strain lacking both the virulence plasmid and caf1M was even further hampered in the ability to prevent uptake and, in this case, essentially all bacteria (95%) were phagocytosed. Thus, F1 and the virulence plasmid-encoded type III system act in concert to make Y. pestis highly resistant to uptake by phagocytes. In contrast to the type III effector proteins YopE and YopH, F1 did not have any influence on the general phagocytic ability of J774 cells. Expression of F1 also reduced the number of bacteria that interacted with the macrophages. This suggests that F1 prevents uptake by interfering at the level of receptor interaction in the phagocytosis process.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

The Roles of Beacons and Surface Features on the Use of Local and Global Geometric Cues for Reorientation

2012 ◽  
Author(s):  
Kent D. Bodily ◽  
Zachary A. Kilday ◽  
Caroline K. Eastman ◽  
Katherine A. Gaskin ◽  
April Graves ◽  
...  
Keyword(s):  
Surface Features ◽  
Geometric Cues
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