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Plasma membrane localization affects the RhoGAP specificity of Pseudomonas ExoS. Cell Microbiol 2007 Sep;9(9):2192-201

Date

05/11/2007

Pubmed ID

17490406

DOI

10.1111/j.1462-5822.2007.00949.x

Scopus ID

2-s2.0-34547913066 (requires institutional sign-in at Scopus site)   19 Citations

Abstract

Pseudomonas aeruginosa ExoS (453 amino acids) is a bifunctional type III cytotoxin, comprising a Rho GTPase-activating protein domain (RhoGAP), and a 14-3-3 dependent ADP-ribosyltransferase domain. In addition, ExoS contains a membrane localization domain (termed MLD, residues 51-77) which localizes and traffics ExoS within intoxicated host cells. While membrane localization has been shown to be essential for ExoS to ADP-ribosylate Ras, the relationship between intracellular localization and expression of RhoGAP activity has not been addressed. In this study, loss of MLD function was observed to abolish expression of ExoS RhoGAP activity in HeLa cells. One mutation within the MLD (R56, R63, D70 mutated to N, RRD-->N) diminished plasma membrane localization and altered the cell rounding phenotype elicited by ExoS RhoGAP. In addition, cell rounding caused by ExoS-MLD(RRD-->N) was reversed by dominant active Rac1, but not dominant active Cdc42, indicating a switch in ExoS RhoGAP substrate specificity. Mutation of the C-terminal polybasic region abolished the ability of dominant active Rac1 to protect HeLa cells from expression of the RhoGAP activity of ExoS-MLD(RRD-->N). This study shows the importance of membrane localization in the targeting of Rho GTPases by ExoS RhoGAP.

Author List

Zhang Y, Deng Q, Porath JA, Williams CL, Pederson-Gulrud KJ, Barbieri JT

Authors

Joseph T. Barbieri PhD Professor in the Microbiology and Immunology department at Medical College of Wisconsin
Carol L. Williams PhD Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin




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

ADP Ribose Transferases
Amino Acid Sequence
Bacterial Toxins
Cell Membrane
Cytotoxins
GTPase-Activating Proteins
HeLa Cells
Humans
Molecular Sequence Data
Mutation
Pseudomonas aeruginosa
Substrate Specificity