Related Experiment Videos
How bacterial ADP-ribosylating toxins recognize substrates.
Jianjun Sun1, Anthony W Maresso, Jung-Ja P Kim
1Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, USA.
Nature Structural & Molecular Biology
|August 18, 2004
Summary
Pseudomonas aeruginosa cytotoxins ExoS and ExoT ADP-ribosylate different substrates due to specific protein regions. Electrostatic properties of these regions determine substrate specificity, explaining toxin interactions.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- ExoS and ExoT are bifunctional type III cytotoxins from Pseudomonas aeruginosa.
- They possess N-terminal RhoGAP and C-terminal ADP-ribosylation domains.
- Despite high amino acid identity, they target distinct substrates.
Purpose of the Study:
- To identify the specific regions of ExoS and ExoT responsible for substrate specificity.
- To elucidate the molecular mechanisms underlying differential substrate recognition.
Main Methods:
- Protein modeling techniques were employed.
- Site-directed mutagenesis was used to probe functional regions.
- Analysis of electrostatic properties of key protein regions.
Main Results:
- Regions B, C, and E on ExoS are necessary and sufficient for target recognition.
- Regions B, C, and E on ExoT are necessary but not sufficient.
- Region A (helix alpha1) on ExoT is crucial for Crk protein recognition.
- Electrostatic properties of regions A, B, C, and E dictate substrate specificity.
Conclusions:
- The identified regions and their electrostatic properties explain the substrate specificity of ExoS and ExoT.
- This understanding can be extended to other bacterial ADP-ribosylating toxins.