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Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
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Structural insights into Pseudomonas aeruginosaType six secretion system exported effector 8
Amaia González-Magaña1, M Ángela Sainz-Polo2, Gabriela Pretre1
1Instituto Biofisika (UPV/EHU, CSIC), Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, University of the Basque Country, 48940 Leioa, Spain.
Journal of Structural Biology
|October 23, 2020
Summary
The Type VI secretion system effector 8 (Tse8) from Pseudomonas aeruginosa is structurally characterized. This cytoactive effector belongs to the Amidase Signature superfamily, revealing its enzymatic function.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- The Type VI secretion system (T6SS) in Pseudomonas aeruginosa secretes effectors like Tse8.
- T6SS provides a competitive advantage and aids in host colonization.
Purpose of the Study:
- To determine the crystal structure of Tse8.
- To elucidate the catalytic mechanism and superfamily classification of Tse8.
Main Methods:
- X-ray crystallography was used to obtain the Tse8 structure.
- Binding affinity experiments were performed to investigate interactions with PMSF.
Main Results:
- The crystal structure of Tse8 revealed a catalytic triad (Lys84-Ser162-Ser186), characteristic of the Amidase Signature superfamily.
- Phenylmethylsulfonyl fluoride (PMSF) binding to Tse8 depends on Ser186, supporting its nucleophilic role.
Conclusions:
- Tse8 is confirmed as a member of the Amidase Signature superfamily.
- Tse8 shares similarities with Peptide Amidase from Stenotrophomonas maltophilia and Glutamyl-tRNA(Gln) amidotransferase subunit A from Staphylococcus aureus.
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