The invasion protein InIB from Listeria monocytogenes activates PLC-gamma1 downstream from PI 3-kinase.
Entry of the bacterial pathogen Listeria monocytogenes into non-phagocytic mammalian cells is mainly mediated by the InlB protein. Here we show that in the human epithelial cell line HEp-2, the invasion protein InlB activates sequentially a p85beta-p110 class I(A) PI 3-kinase and the phospholipase C-gamma1 (PLC-gamma1) without detectable tyrosine phosphorylation of PLC-gamma1. Purified InlB stimulates association of PLC-gamma1 with one or more tyrosine-phosphorylated proteins, followed by a transient increase in intracellular inositol 1,4,5-trisphosphate (IP3) levels and a release of intracellular Ca2+ in a PI 3-kinase-dependent manner. Infection of HEp-2 cells with wild-type L. monocytogenes bacteria also induces association of PLC-gamma1 with phosphotyrosyl proteins. This interaction is undetectable upon infection with a deltainlB mutant revealing an InlB specific signal. Interestingly, pharmacological or genetic inactivation of PLC-gamma1 does not significantly affect InlB-mediated bacterial uptake, suggesting that InlB-mediated PLC-gamma1 activation and calcium mobilization are involved in post-internalization steps.
Bierne
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H
Unité des Interactions Bactéries-Cellules, Institut Pasteur, Paris, France.
Dramsi
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S
Gratacap
M P
MP
Randriamampita
C
C
Carpenter
G
G
Payrastre
B
B
Cossart
P
P
D001426:Bacterial Proteins; D002118:Calcium / Q000378:metabolism; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000382:microbiology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008089:Listeria monocytogenes / Q000472:pathogenicity* / Q000502:physiology; D008088:Listeriosis / Q000382:microbiology*; D008565:Membrane Proteins / Q000378:metabolism / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051966:Phospholipase C gamma; D010766:Phosphorylation; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D014774:Virulence
D001426:Bacterial Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; C095768:inlB protein, Listeria monocytogenes; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D002118:Calcium