Naslov
Temporal and spatial trigger of post-exponential virulence-associated regulatory cascades by Legionella pneumophila after bacterial escape into the host cell cytosol

Autori
Molmeret, Maëlle ; Jones, Snake ; Šantić, Marina ; Habyarimana, Fabien ; Garcia Esteban, Maria Teresa ; Abu Kwaik, Yousef

Izvornik
Environmental microbiology (1462-2912) 13 (2010), 1-2; 1350-1365

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Legionella; FlaA; phagosomal escape

Sažetak
During late stages of infection and prior to lysis of the infected macrophages or amoeba, the Legionella pneumophila-containing phagosome becomes disrupted, followed by bacterial escape into the host cell cytosol, where the last few rounds of bacterial proliferation occur prior to lysis of the plasma membrane. This coincides with growth transition into the post-exponential (PE) phase, which is controlled by regulatory cascades including RpoS and the LetA/S two-component regulator. Whether the temporal expression of flagella by the regulatory cascades at the PE phase is exhibited within the phagosome or after bacterial escape into the host cell cytosol is not known. We have utilized fluorescence microscopy-based phagosome integrity assay to differentiate between vacuolar and cytosolic bacteria/or bacteria within disrupted phagosomes. Our data show that during late stages of infection, expression of FlaA is triggered after bacterial escape into the macrophage cytosol and the peak of FlaA expression is delayed for few hours after cytosolic residence of the bacteria. Importantly, bacterial escape into the host cell cytosol is independent of flagella, RpoS and the two-component regulator LetA/S, which are all triggered by L. pneumophila upon growth transition into the PE phase. Disruption of the phagosome and bacterial escape into the cytosol of macrophages is independent of the bacterial pore-forming activity, and occurs prior to the induction of apoptosis during late stages of infection. We conclude that the temporal and spatial engagement of virulence-associated regulatory cascades by L. pneumophila at the PE phase is temporally and spatially triggered after phagosomal escape and bacterial residence in the host cell cytosol.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti, Kliničke medicinske znanosti

POVEZANOST RADA