scholarly journals Characterization of Salmonella enterica Derivatives Harboring Defined aroC and Salmonella Pathogenicity Island 2 Type III Secretion System (ssaV) Mutations by Immunization of Healthy Volunteers

2002 ◽  
Vol 70 (7) ◽  
pp. 3457-3467 ◽  
Author(s):  
Zoë Hindle ◽  
Steven N. Chatfield ◽  
Jo Phillimore ◽  
Matthew Bentley ◽  
Julie Johnson ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
High Titer ◽  
Serum Antibody ◽  
Immunoglobulin A ◽  
Secretion Systems ◽  
Antibody Secreting Cell ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Serovar Typhimurium

ABSTRACT The attenuation and immunogenicity of two novel Salmonella vaccine strains, Salmonella enterica serovar Typhi (Ty2 ΔaroC ΔssaV, designated ZH9) and S. enterica serovar Typhimurium (TML ΔaroC ΔssaV, designated WT05), were evaluated after their oral administration to volunteers as single escalating doses of 107, 108, or 109 CFU. ZH9 was well tolerated, not detected in blood, nor persistently excreted in stool. Six of nine volunteers elicited anti-serovar Typhi lipopolysaccharide (LPS) immunoglobulin A (IgA) antibody-secreting cell (ASC) responses, with three of three vaccinees receiving 108 and two of three receiving 109 CFU which elicited high-titer LPS-specific serum IgG. WT05 was also well tolerated with no diarrhea, although the administration of 108 and 109 CFU resulted in shedding in stools for up to 23 days. Only volunteers immunized with 109 CFU of WT05 mounted detectable serovar Typhimurium LPS-specific ASC responses and serum antibody responses were variable. These data indicate that mutations in type III secretion systems may provide a route to the development of live vaccines in humans and highlight significant differences in the potential use of serovars Typhimurium and Typhi.

scholarly journals Complex Function for SicA, a Salmonella enterica Serovar Typhimurium Type III Secretion-Associated Chaperone

2000 ◽  
Vol 182 (8) ◽  
pp. 2262-2268 ◽  
Author(s):  
Stephanie C. Tucker ◽  
Jorge E. Galán
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Complex Function ◽  
Loss Of Function ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Serovar Typhimurium ◽  
Low Molecular Weight Proteins

ABSTRACT Salmonella enterica encodes a type III secretion system within a pathogenicity island located at centisome 63 that is essential for virulence. All type III secretion systems require the function of a family of low-molecular-weight proteins that aid the secretion process by acting as partitioning factors and/or secretion pilots. One such protein is SicA, which is encoded immediately upstream of the type III secreted proteins SipB and SipC. We found that the absence of SicA results in the degradation of both SipB and SipC. Interestingly, in the absence of SipC, SipB was not only stable but also secreted at wild-type levels in a sicA mutant background, indicating that SicA is not required for SipB secretion. We also found that SicA is capable of binding both SipB and SipC. These results are consistent with a SicA role as a partitioning factor for SipB and SipC, thereby preventing their premature association and degradation. We also found that introduction of a sicA null mutation results in the lack of expression of SopE, another type III-secreted protein. Such an effect was shown to be transcriptional. Introduction of a loss-of-function sipC mutation into the sicAmutant background rescued sopE expression. These results indicate that the effect of sicA on sopEexpression is indirect and most likely exerted through a regulatory factor(s) partitioned by SicA from SipC. These studies therefore describe a surprisingly complex function for the Salmonella enterica type III secretion-associated chaperone SicA.

scholarly journals Impact of Salmonella enterica Type III Secretion System Effectors on the Eukaryotic Host Cell

2012 ◽  
Vol 2012 ◽  
pp. 1-36 ◽  
Author(s):  
Francisco Ramos-Morales
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Current Knowledge ◽  
Cellular Level ◽  
Host Cells ◽  
Secretion Systems ◽  
Type Iii ◽  
Cellular Processes ◽  
Type Iii Secretion Systems ◽  
Near Future

Type III secretion systems are molecular machines used by many Gram-negative bacterial pathogens to inject proteins, known as effectors, directly into eukaryotic host cells. These proteins manipulate host signal transduction pathways and cellular processes to the pathogen’s advantage. Salmonella enterica possesses two virulence-related type III secretion systems that deliver more than forty effectors. This paper reviews our current knowledge about the functions, biochemical activities, host targets, and impact on host cells of these effectors. First, the concerted action of effectors at the cellular level in relevant aspects of the interaction between Salmonella and its hosts is analyzed. Then, particular issues that will drive research in the field in the near future are discussed. Finally, detailed information about each individual effector is provided.

scholarly journals Effect of the O-Antigen Length of Lipopolysaccharide on the Functions of Type III Secretion Systems in Salmonella enterica

2009 ◽  
Vol 77 (12) ◽  
pp. 5458-5470 ◽  
Author(s):  
Stefanie U. Hölzer ◽  
Markus C. Schlumberger ◽  
Daniela Jäckel ◽  
Michael Hensel
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Defense Mechanisms ◽  
Host Cells ◽  
Effector Protein ◽  
Secretion Systems ◽  
Type Iii ◽  
O Antigen ◽  
T3ss Effector ◽  
Type Iii Secretion Systems

ABSTRACT The virulence of Salmonella enterica critically depends on the functions of two type III secretion systems (T3SS), with the Salmonella pathogenicity island 1 (SPI1)-encoded T3SS required for host cell invasion and the SPI2-T3SS enabling Salmonella to proliferate within host cells. A further T3SS is required for the assembly of the flagella. Most serovars of Salmonella also possess a lipopolysaccharide with a complex O-antigen (OAg) structure. The number of OAg units attached to the core polysaccharide varies between 16 and more than 100 repeats, with a trimodal distribution. This work investigated the correlation of the OAg length with the functions of the SPI1-T3SS and the SPI2-T3SS. We observed that the number of repeats of OAg units had no effect on bacterial motility. The interaction of Salmonella with epithelial cells was altered if the OAg structure was changed by mutations in regulators of OAg. Strains defective in synthesis of very long or long and very long OAg species showed increased translocation of a SPI1-T3SS effector protein and increased invasion. Invasion of a strain entirely lacking OAg was increased, but this mutant strain also showed increased adhesion. In contrast, translocation of a SPI2-T3SS effector protein and intracellular replication were not affected by modification of the OAg length. Mutant strains lacking the entire OAg or long and very long OAg were highly susceptible to complement killing. These observations indicate that the architecture of the outer membrane of Salmonella is balanced to permit sufficient T3SS function but also to confer optimal protection against antimicrobial defense mechanisms.

scholarly journals Optimization of the Delivery of Heterologous Proteins by the Salmonella enterica Serovar Typhimurium Type III Secretion System for Vaccine Development

2006 ◽  
Vol 74 (10) ◽  
pp. 5826-5833 ◽  
Author(s):  
Li-Mei Chen ◽  
Gabriel Briones ◽  
Ruben O. Donis ◽  
Jorge E. Galán
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Vaccine Development ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Antigen Delivery ◽  
Secretion Systems ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT Type III protein secretion systems, which are organelles with the capacity to deliver bacterial proteins into host cells, have been adapted to deliver heterologous antigens for vaccine development. A limitation of these antigen delivery systems is that some proteins are not amenable to secretion through this pathway. We show here that proteins from the simian and human immunodeficiency viruses that are not permissive for secretion through a Salmonella enterica serovar Typhimurium type III secretion system can be modified to travel this secretion pathway by introduction of discrete mutations. Proteins optimized for secretion were presented more efficiently via the major histocompatibility complex class I pathway and were able to induce a better immune response.

scholarly journals Salicylidene Acylhydrazides That Affect Type III Protein Secretion in Salmonella enterica Serovar Typhimurium

2007 ◽  
Vol 51 (8) ◽  
pp. 2867-2876 ◽  
Author(s):  
Aurel Negrea ◽  
Eva Bjur ◽  
Sofia Eriksson Ygberg ◽  
Mikael Elofsson ◽  
Hans Wolf-Watz ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Effector Proteins ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Serovar Typhimurium ◽  
Type Iii Protein Secretion ◽  
Bacterial Replication

ABSTRACT A collection of nine salicylidene acylhydrazide compounds were tested for their ability to inhibit the activity of virulence-associated type III secretion systems (T3SSs) in Salmonella enterica serovar Typhimurium. The compounds strongly affected Salmonella pathogenicity island 1 (SPI1) T3SS-mediated invasion of epithelial cells and in vitro secretion of SPI1 invasion-associated effector proteins. The use of a SPI1 effector β-lactamase fusion protein implicated intracellular entrapment of the protein construct upon application of a salicylidene acylhydrazide, whereas the use of chromosomal transcriptional gene fusions revealed a compound-mediated transcriptional silencing of SPI1. Salicylidene acylhydrazides also affected intracellular bacterial replication in murine macrophage-like cells and blocked the transport of an epitope-tagged SPI2 effector protein. Two of the compounds significantly inhibited bacterial motility and expression of extracellular flagellin. We conclude that salicylidene acylhydrazides affect bacterial T3SS activity in S. enterica and hence could be used as lead substances when designing specific inhibitors of bacterial T3SSs in order to pharmaceutically intervene with bacterial virulence.

scholarly journals Genetic Analysis of the Salmonella enterica Type III Secretion-Associated ATPase InvC Defines Discrete Functional Domains

2004 ◽  
Vol 186 (8) ◽  
pp. 2402-2412 ◽  
Author(s):  
Yukihiro Akeda ◽  
Jorge E. Galán
Keyword(s):  
Amino Acid ◽  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Sequence Similarity ◽  
Amino Acid Sequence Similarity ◽  
Amino Acid Residues ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Discrete Domains

ABSTRACT An essential component of all type III secretion systems is a highly conserved ATPase that shares significant amino acid sequence similarity to the β subunit of the F0F1 ATPases and is thought to provide the energy for the secretion process. We have performed a genetic and functional analysis of InvC, the ATPase associated with the Salmonella enterica type III secretion system encoded within its pathogenicity island 1. Through a mutagenesis analysis, we have identified amino acid residues that are essential for specific activities of InvC, such as nucleotide hydrolysis and membrane binding. This has allowed us to define discrete domains of InvC that are specifically associated with different essential activities of this protein.

scholarly journals Identification of New Secreted Effectors in Salmonella enterica Serovar Typhimurium

2005 ◽  
Vol 73 (10) ◽  
pp. 6260-6271 ◽  
Author(s):  
Kaoru Geddes ◽  
Micah Worley ◽  
George Niemann ◽  
Fred Heffron
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Bacterial Species ◽  
Effector Proteins ◽  
Host Cells ◽  
Secretion Systems ◽  
Cell Cytoplasm ◽  
Type Iii ◽  
Serovar Typhimurium ◽  
Infected Cells

ABSTRACTA common theme in bacterial pathogenesis is the secretion of bacterial products that modify cellular functions to overcome host defenses. Gram-negative bacterial pathogens use type III secretion systems (TTSSs) to inject effector proteins into host cells. The genes encoding the structural components of the type III secretion apparatus are conserved among bacterial species and can be identified by sequence homology. In contrast, the sequences of secreted effector proteins are less conserved and are therefore difficult to identify. A strategy was developed to identify virulence factors secreted bySalmonella entericaserovar Typhimurium into the host cell cytoplasm. We constructed a transposon, which we refer to as mini-Tn5-cycler, to generate translational fusions betweenSalmonellachromosomal genes and a fragment of the calmodulin-dependent adenylate cyclase gene derived fromBordetella pertussis(cyaA′). In-frame fusions to bacterial proteins that are secreted into the eukaryotic cell cytoplasm were identified by high levels of cyclic AMP in infected cells. The assay was sufficiently sensitive that a single secreted fusion could be identified among several hundred that were not secreted. This approach identified three new effectors as well as seven that have been previously characterized. A deletion of one of the new effectors,steA(Salmonellatranslocated effector A), attenuated virulence. In addition, SteA localizes to thetrans-Golgi network in both transfected and infected cells. This approach has identified new secreted effector proteins inSalmonellaand will likely be useful for other organisms, even those in which genetic manipulation is more difficult.

scholarly journals Synthesis and Localization of the Salmonella SPI-1 Type III Secretion Needle Complex Proteins PrgI and PrgJ

2003 ◽  
Vol 185 (11) ◽  
pp. 3480-3483 ◽  
Author(s):  
Anand Sukhan ◽  
Tomoko Kubori ◽  
Jorge E. Galán
Keyword(s):  
Mutant Strain ◽  
Type Iii Secretion ◽  
Wild Type ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Mutant Strains ◽  
Serovar Typhimurium ◽  
Needle Protein ◽  
Protein Instability

ABSTRACT An essential component of type III secretion systems (TTSS) is a supramolecular structure termed the needle complex. In Salmonella enterica, at least four proteins make up this structure: InvG, PrgH, PrgK, and PrgI. Another protein, PrgJ, is thought to play a role in the assembly of this structure, but its function is poorly understood. We have analyzed the expression and localization of PrgJ and the needle protein PrgI in different S. enterica serovar Typhimurium mutant strains. We found that the levels of PrgI and PrgJ were significantly reduced in a TTSS-deficient invA mutant strain and that the decreased levels were due to protein instability. In addition, we found that PrgJ, although associated with the needle complex in wild-type S. enterica serovar Typhimurium, was absent from needle complexes obtained from an invJ mutant strain, which exhibits very long needle substructures. We suggest that PrgJ is involved in capping the needle substructure of the needle complex.

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