Publication Date:
2010-04-17
Description:
Salmonella enterica is an important intracellular bacterial pathogen of humans and animals. It replicates within host-cell vacuoles by delivering virulence (effector) proteins through a vacuolar membrane pore made by the Salmonella pathogenicity island 2 (SPI-2) type III secretion system (T3SS). T3SS assembly follows vacuole acidification, but when bacteria are grown at low pH, effector secretion is negligible. We found that effector secretion was activated at low pH from mutant strains lacking a complex of SPI-2-encoded proteins SsaM, SpiC, and SsaL. Exposure of wild-type bacteria to pH 7.2 after growth at pH 5.0 caused dissociation and degradation of SsaM/SpiC/SsaL complexes and effector secretion. In infected cells, loss of the pH 7.2 signal through acidification of host-cell cytosol prevented complex degradation and effector translocation. Thus, intravacuolar Salmonella senses host cytosolic pH, resulting in the degradation of regulatory complex proteins and effector translocation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yu, Xiu-Jun -- McGourty, Kieran -- Liu, Mei -- Unsworth, Kate E -- Holden, David W -- 074553/Z/04/Z/Wellcome Trust/United Kingdom -- G0800148/Medical Research Council/United Kingdom -- New York, N.Y. -- Science. 2010 May 21;328(5981):1040-3. doi: 10.1126/science.1189000. Epub 2010 Apr 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section of Microbiology, Centre for Molecular Microbiology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20395475" target="_blank"〉PubMed〈/a〉
Keywords:
Bacterial Processes
;
Bacterial Proteins/chemistry/genetics/*metabolism
;
Cytosol/chemistry
;
Genomic Islands
;
HeLa Cells
;
Humans
;
Hydrogen-Ion Concentration
;
Molecular Chaperones/metabolism
;
Multiprotein Complexes/metabolism
;
Mutation
;
Salmonella typhimurium/genetics/growth & development/*metabolism/pathogenicity
;
Vacuoles/metabolism/*microbiology
;
Virulence Factors/*metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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