Faculty Collaboration Database

Characterization of Pseudomonas aeruginosa exoenzyme S as a bifunctional enzyme in J774A.1 macrophages. Infect Immun 2003 Sep;71(9):5296-305

Date

08/23/2003

Pubmed ID

12933877

Pubmed Central ID

PMC187317

DOI

10.1128/IAI.71.9.5296-5305.2003

Scopus ID

2-s2.0-0041322625 (requires institutional sign-in at Scopus site)   51 Citations

Abstract

Pseudomonas aeruginosa exoenzyme S (ExoS) is a type III secretion (TTS) effector, which includes both a GTPase-activating protein (GAP) activity toward the Rho family of low-molecular-weight G (LMWG) proteins and an ADP-ribosyltransferase (ADPRT) activity that targets LMWG proteins in the Ras, Rab, and Rho families. The coordinate function of both activities of ExoS in J774A.1 macrophages was assessed by using P. aeruginosa strains expressing and translocating wild-type ExoS or ExoS defective in GAP and/or ADPRT activity. Distinct and coordinated functions were identified for both domains. The GAP activity was required for the antiphagocytic effect of ExoS and was linked to interference of lamellopodium and membrane ruffle formation. Alternatively, the ADPRT activity of ExoS altered cellular adherence and morphology and was linked to effects on filopodium formation. The cellular mechanism of ExoS GAP activity included an inactivation of Rac1 function, as determined in p21-activated kinase 1-glutathione S-transferase (GST) pull-down assays. The ADPRT activity of ExoS targeted Ras and RalA but not Rab or Rho proteins, and Ral binding protein 1-GST pull-down assays identified an effect of ExoS ADPRT activity on RalA activation. The results from these studies confirm the bifunctional nature of ExoS activity within macrophages when translocated by TTS.

Author List

Rocha CL, Coburn J, Rucks EA, Olson JC

Author

Jenifer Coburn PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

ADP Ribose Transferases
Animals
Bacterial Toxins
Biological Transport, Active
Cell Line
GTP Phosphohydrolases
GTPase-Activating Proteins
Macrophages
Mice
Microscopy, Electron, Scanning
Phagocytosis
Pseudomonas aeruginosa
rac1 GTP-Binding Protein
ral GTP-Binding Proteins