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Modulation of Host Cell Endocytosis by the Type III Cytotoxin, Pseudomonas ExoS
Author(s) -
Deng Qing,
Barbieri Joseph T.
Publication year - 2008
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2008.00808.x
Subject(s) - internalization , endocytosis , biology , endosome , microbiology and biotechnology , endocytic cycle , signal transducing adaptor protein , adp ribosylation factor , signal transduction , cell , biochemistry , intracellular , endoplasmic reticulum , golgi apparatus
Pseudomonas aeruginosa ExoS is a bifunctional type III cytotoxin that possesses Rho GTPase‐activating protein (RhoGAP) and ADP‐ribosyltransferase (ADPr) activities. In the current study, the RhoGAP and ADPr activities of ExoS were tested for the ability to disrupt mammalian epithelial cell physiology. RhoGAP, but not ADPr, inhibited internalization/phagocytosis of bacteria, while ADPr, but not RhoGAP, inhibited vesicle trafficking, both general fluid‐phase uptake and EGF‐activated EGF receptor (EGFR) degradation. In ADPr‐intoxicated cells, upon EGF activation, EGFR co‐localized with clathrin‐coated vesicles (CCV), which did not mature into Rab5‐positive early endosomes. Constitutively, active Rab5 recruited EGFR from CCV to early endosomes. Consistent with the inhibition of Rab5 function by ADPr, several Rab proteins including Rab5 and 9, but not Rab4, were ADP ribosylated by ExoS. Thus, the two enzymatic activities of ExoS have different effects on epithelial cells with RhoGAP inhibiting bacterial internalization and ADPr interfering with CCV maturation. The ability ADPr to inhibit mammalian vesicle trafficking provides a new mechanism for bacterial toxin‐mediated virulence.