Document Detail

Identification and characterization of an RTX toxin in the emerging pathogen Kingella kingae.
MedLine Citation:
PMID:  17098895     Owner:  NLM     Status:  MEDLINE    
Kingella kingae is an emerging bacterial pathogen that is increasingly recognized as the causative agent of a variety of pediatric diseases, including septic arthritis and osteomyelitis. The pathogenesis of K. kingae disease is believed to begin with colonization of the upper respiratory tract. In the present study, we examined interactions between K. kingae and cultured respiratory epithelial cells and observed potent cytotoxicity, detected by both microscopy and lactic acid dehydrogenase (LDH) release assays. Experiments with synovial and macrophage cell lines revealed cytotoxicity for these cell types as well. Using mariner mutagenesis and a screen for loss of cytotoxicity, a genetic locus encoding an RTX toxin system was identified. Disruption of the K. kingae RTX locus resulted in a loss of cytotoxicity for respiratory epithelial, synovial, and macrophage cell lines. DNA sequence analysis demonstrated that the RTX locus is flanked by insertion elements and has a reduced G+C content compared to that of the whole genome. Two relatively less invasive Kingella species, K. oralis and K. denitrificans, were found to be noncytotoxic and to lack the RTX region, as determined by LDH release assays and Southern blotting. We concluded that K. kingae expresses an RTX toxin that has wide cellular specificity and was likely acquired horizontally. The possible roles for this toxin in the pathogenesis of K. kingae disease include breaching of the epithelial barrier and destruction of target tissues, such as synovium (joint lining).
Thomas E Kehl-Fie; Joseph W St Geme
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2006-11-10
Journal Detail:
Title:  Journal of bacteriology     Volume:  189     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2007 Jan 
Date Detail:
Created Date:  2006-12-29     Completed Date:  2007-03-01     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  430-6     Citation Subset:  IM    
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63310, USA.
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MeSH Terms
Bacterial Toxins / genetics*,  metabolism
Cell Line
Cell Line, Tumor
Cell Survival
Epithelial Cells / cytology,  metabolism,  microbiology
Gene Order
Kingella kingae / genetics*,  growth & development,  ultrastructure
L-Lactate Dehydrogenase / metabolism
Macrophages / cytology,  metabolism,  microbiology
Microscopy, Electron, Transmission
Molecular Sequence Data
Multigene Family
Mutant Proteins / genetics,  metabolism
Grant Support
Reg. No./Substance:
0/Bacterial Toxins; 0/Mutant Proteins; EC Dehydrogenase

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