RT Journal Article
T1 Membrane Vesicles Shed by Legionella pneumophila Inhibit Fusion of  Phagosomes with Lysosomes
A1 Fernández Moreira, Esteban
A1 Helbig, Juergen H.
A1 Swanson, Michele S.
AB When cultured in broth to the transmissive phase, Legionella pneumophila infects macrophages by inhibiting phagosome maturation, whereas replicative-phase cells are transported to the lysosomes. Here we report that the ability of L. pneumophila to inhibit phagosome-lysosome fusion correlated with developmentally regulated modifications of the pathogen's surface, as judged by its lipopolysaccharide profile and by its binding to a sialic acid-specific lectin and to the hydrocarbon hexadecane. Likewise, the composition of membrane vesicles shed by L. pneumophila was developmentally regulated, based on binding to the lectin and to the lipopolysaccharide-specific monoclonal antibody 3/1. Membrane vesicles were sufficient to inhibit phagosome-lysosome fusion by a mechanism independent of type IV secretion, since only ∼25% of beads suspended with or coated by vesicles from transmissive phase wild type or dotA secretion mutants colocalized with lysosomal probes, whereas ∼75% of beads were lysosomal when untreated or presented with vesicles from the L. pneumophila letA regulatory mutant or E. coli. As observed previously for L. pneumophila infection of mouse macrophages, vesicles inhibited phagosome-lysosome fusion only temporarily; by 10 h after treatment with vesicles, macrophages delivered ∼72% of ingested beads to lysosomes. Accordingly, in the context of the epidemiology of the pneumonia Legionnaires' disease and virulence mechanisms of Leishmania and Mycobacteria, we discuss a model here in which L. pneumophila developmentally regulates its surface composition and releases vesicles into phagosomes that inhibit their fusion with lysosomes.
PB American Society for Microbiology
SN 0019-9567
YR 2006
FD 2006-06
LK https://hdl.handle.net/20.500.14352/124947
UL https://hdl.handle.net/20.500.14352/124947
LA eng
NO Fernandez-Moreira E, Helbig JH, Swanson MS2006.Membrane Vesicles Shed by Legionella pneumophila Inhibit Fusion of Phagosomes with Lysosomes. Infect Immun74:.https://doi.org/10.1128/iai.01382-05
DS Docta Complutense
RD 18 dic 2025