This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rocha, C. L. Articles by Olson, J. C. Search for Related Content PubMed PubMed Citation Articles by Rocha, C. L. Articles by Olson, J. C.

Characterization of Pseudomonas aeruginosa Exoenzyme S as a Bifunctional Enzyme in J774A.1 Macrophages

Claudia L. Rocha,¹ Jenifer Coburn,² Elizabeth A. Rucks,^1, and Joan C. Olson^1*

Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina 29425,¹ Division of Geographic Medicine and Infectious Diseases, Tufts-New England Medical Center, Boston, Massachusetts 02111²

Received 24 February 2003/ Returned for modification 1 April 2003/ Accepted 4 June 2003

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.

Editor: D. L. Burns

Present address: Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506-9177.

This article has been cited by other articles:

• Coburn, B., Sekirov, I., Finlay, B. B. (2007). Type III Secretion Systems and Disease. Clin. Microbiol. Rev. 20: 535-549 [Abstract] [Full Text]  
• Avet-Rochex, A., Perrin, J., Bergeret, E., Fauvarque, M.-O. (2007). Rac2 is a major actor of Drosophila resistance to Pseudomonas aeruginosa acting in phagocytic cells. GENES CELLS 12: 1193-1204 [Abstract] [Full Text]  
• Shaver, C. M., Hauser, A. R. (2006). Interactions between effector proteins of the Pseudomonas aeruginosa type III secretion system do not significantly affect several measures of disease severity in mammals. Microbiology 152: 143-152 [Abstract] [Full Text]  
• Rocha, C. L., Rucks, E. A., Vincent, D. M., Olson, J. C. (2005). Examination of the Coordinate Effects of Pseudomonas aeruginosa ExoS on Rac1. Infect. Immun. 73: 5458-5467 [Abstract] [Full Text]  
• Rucks, E. A., Olson, J. C. (2005). Characterization of an ExoS Type III Translocation-Resistant Cell Line. Infect. Immun. 73: 638-643 [Abstract] [Full Text]  
• Shaver, C. M., Hauser, A. R. (2004). Relative Contributions of Pseudomonas aeruginosa ExoU, ExoS, and ExoT to Virulence in the Lung. Infect. Immun. 72: 6969-6977 [Abstract] [Full Text]  
• Maresso, A. W., Baldwin, M. R., Barbieri, J. T. (2004). Ezrin/Radixin/Moesin Proteins Are High Affinity Targets for ADP-ribosylation by Pseudomonas aeruginosa ExoS. J. Biol. Chem. 279: 38402-38408 [Abstract] [Full Text]