Document Detail


pH-dependent secretion of SseB, a product of the SPI-2 type III secretion system of Salmonella typhimurium.
MedLine Citation:
PMID:  10447889     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The type III secretion system of Salmonella pathogenicity island 2 (SPI-2) is required for bacterial replication inside macrophages. SseB has been considered a putative target of the secretion system on the basis of its similarity with EspA, a protein secreted by the type III secretion system of enteropathogenic Escherichia coli (EPEC). EspA forms a filamentous structure on the bacterial cell surface and is involved in translocation of proteins into the eukaryotic cytosol. In this paper, we show that SseB is a secreted protein that associates with the surface of the bacterial cell and might, therefore, also be required for delivery of SPI-2 effector proteins to the eukaryotic cell cytosol. SseB begins to accumulate inside the bacterial cell when the culture enters early stationary phase. However, SseB is only secreted if the bacteria are grown at low pH or if the pH is shifted after growth from 7.0 to below pH 5.0. The secretion occurs within minutes of acidification and is totally dependent on a functional SPI-2 type III secretion system. As the pH of the Salmonella-containing vacuole inside host cells has been shown to acidify to between pH 4.0 and 5.0, and as SPI-2 gene expression occurs inside host cells, low pH might be a physiological stimulus for SPI-2-mediated secretion in vivo.
Authors:
C R Beuzón; G Banks; J Deiwick; M Hensel; D W Holden
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Molecular microbiology     Volume:  33     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  1999 Aug 
Date Detail:
Created Date:  1999-12-14     Completed Date:  1999-12-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  806-16     Citation Subset:  IM    
Affiliation:
Department of Infectious Diseases, Imperial College School of Medicine, Du Cane Road, London W12 0NN, UK.
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MeSH Terms
Descriptor/Qualifier:
Agglutination Tests
Bacterial Proteins / metabolism*
Cell Division
Endopeptidase K / metabolism
Escherichia coli
Escherichia coli Proteins*
Genes, Reporter
Hydrogen-Ion Concentration
Membrane Proteins / metabolism
Mutation
Recombinant Proteins
Salmonella typhimurium / metabolism*
Chemical
Reg. No./Substance:
0/Bacterial Proteins; 0/Escherichia coli Proteins; 0/EspA protein, E coli; 0/Membrane Proteins; 0/Recombinant Proteins; 0/SseB protein, E coli; EC 3.4.21.64/Endopeptidase K

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