Document Detail

A novel PhoP-regulated locus encoding the cytolysin ClyA and the secreted invasin TaiA of Salmonella enterica serovar Typhi is involved in virulence.
MedLine Citation:
PMID:  19202096     Owner:  NLM     Status:  MEDLINE    
Salmonella enterica serovar Typhi causes a human-restricted systemic infection called typhoid fever. We have identified a Typhi genomic region encoding two ORFs, STY1498 and STY1499, that are expressed during infection of human macrophages and organized in an operon. STY1498 corresponds to clyA, which encodes a pore-forming cytolysin, and STY1499 encodes a 27 kDa protein, without any attributed function, which we have named TaiA (Typhi-associated invasin A). In order to evaluate the roles of these genes in Typhi pathogenesis, isogenic Typhi strains harbouring a non-polar mutation of either clyA or taiA were constructed. In macrophages, taiA was involved in increasing phagocytosis, as taiA deletion reduced bacterial uptake, whereas clyA reduced or controlled bacterial growth, as clyA deletion enhanced Typhi survival within macrophages without affecting cytotoxicity. In epithelial cells, deletion of taiA had no effect on invasion, whereas deletion of clyA enhanced the Typhi invasion rate, and reduced cytotoxicity. Overexpression of taiA in Typhi or in Escherichia coli resulted in a higher invasion rate of epithelial cells. We have demonstrated that TaiA is secreted independently of both the Salmonella pathogenicity island (SPI)-1 and the SPI-2 type three secretion systems. We have shown that this operon is regulated by the virulence-associated regulator PhoP. Moreover, our results revealed that products of this operon might be involved in promoting the use of macrophages as a sheltered reservoir for Typhi and allowing long-term persistence inside the host.
Sébastien P Faucher; Chantal Forest; Maxime Béland; France Daigle
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Microbiology (Reading, England)     Volume:  155     ISSN:  1350-0872     ISO Abbreviation:  Microbiology (Reading, Engl.)     Publication Date:  2009 Feb 
Date Detail:
Created Date:  2009-02-09     Completed Date:  2009-03-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9430468     Medline TA:  Microbiology     Country:  England    
Other Details:
Languages:  eng     Pagination:  477-88     Citation Subset:  IM    
Department of Microbiology and Immunology, University of Montreal, CP 6128 Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada.
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MeSH Terms
Adhesins, Bacterial / genetics,  metabolism*
Bacterial Proteins / genetics,  metabolism*
Cell Line
Epithelial Cells / microbiology
Hela Cells
Hemolysin Proteins / genetics,  metabolism*
Macrophages / microbiology
Perforin / genetics,  metabolism*
Protein Transport
Salmonella typhi / genetics,  growth & development,  metabolism,  pathogenicity*
Typhoid Fever / microbiology*
Reg. No./Substance:
0/Adhesins, Bacterial; 0/Bacterial Proteins; 0/Hemolysin Proteins; 125360-99-8/PhoP protein, Bacteria; 126465-35-8/Perforin; 159035-78-6/ApxI toxin, Bacteria

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