Document Detail


Icm/dot-dependent upregulation of phagocytosis by Legionella pneumophila.
MedLine Citation:
PMID:  11722729     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Legionella pneumophila is the causative agent of Legionnaires' disease, a severe pneumonia. Dependent on the icm/dot loci, L. pneumophila survives and replicates in macrophages and amoebae within a specialized phagosome that does not fuse with lysosomes. Here, we report that phagocytosis of wild-type L. pneumophila is more efficient than uptake of icm/dot mutants. Compared with the wild-type strain JR32, about 10 times fewer icm/dot mutant bacteria were recovered from HL-60 macrophages in a gentamicin protection assay. The defect in phagocytosis of the mutants could be complemented by supplying the corresponding genes on a plasmid. Using fluorescence microscopy and green fluorescent protein (GFP)-expressing strains, 10-20 times fewer icm/dot mutant bacteria were found to be internalized by HL-60 cells and human monocyte-derived macrophages (HMMPhi). Compared with icm/dot mutants, wild-type L. pneumophila infected two to three times more macrophages and yielded a population of highly infected host cells (15-70 bacteria per macrophage) that was not observed with icm/dot mutant strains. Wild-type and icmT mutant bacteria were found to adhere similarly and compete for binding to HMMPhi. In addition, wild-type L. pneumophila was also phagocytosed more efficiently by Acanthamoeba castellanii, indicating that the process is independent of adherence receptor(s). Wild-type L. pneumophila enhanced phagocytosis of an icmT mutant strain in a synchronous co-infection, suggesting that increased phagocytosis results from (a) secreted effector(s) acting in trans.
Authors:
H Hilbi; G Segal; H A Shuman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Molecular microbiology     Volume:  42     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  2001 Nov 
Date Detail:
Created Date:  2001-11-27     Completed Date:  2002-02-11     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  603-17     Citation Subset:  IM    
Affiliation:
Department of Microbiology, College of Physicians and Surgeons, Columbia University, 701 West 168th Street, New York, NY 10032, USA.
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MeSH Terms
Descriptor/Qualifier:
Acanthamoeba / microbiology
Animals
Anti-Bacterial Agents / pharmacology
Bacterial Adhesion
Bacterial Proteins / genetics,  metabolism
Carrier Proteins / genetics,  metabolism*
Cell Line
Gentamicins / pharmacology
Humans
Legionella pneumophila / genetics,  metabolism,  physiology*
Macrophages / microbiology*
Membrane Proteins / genetics,  metabolism*
Mice
Microscopy, Fluorescence
Mutation
Phagocytosis / physiology*
Up-Regulation
Grant Support
ID/Acronym/Agency:
AI 23549/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Bacterial Proteins; 0/Carrier Proteins; 0/Gentamicins; 0/Membrane Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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