Correlation Engine 2.0
Clear Search sequence regions

Pseudomonas aeruginosa is a ubiquitous and opportunistic pathogen that uses the type III secretion system (TTSS) to inject effector proteins directly into the cytosol of target cells to subvert the host cell's functions. Specialized bacterial chaperones are required for effective secretion of some effectors. To identify the chaperone of ExoS, the representative effector secreted by the TTSS of P. aeruginosa, we analyzed the role of a postulated chaperone termed Orf1. By allelic exchange, we constructed the mutant with the deletion of gene Orf1. Analysis of secreted and cell-associated fractions was performed by SDS-PAGE and Western blotting. Using strain expressing in trans Orf1, tagged by V5 polypeptide and histidine, protein-protein interaction was determined by affinity resin pull-down assay in combination with MALDI-TOF. The role of Orf1 in the expression of exoS was evaluated by gene reporter analysis. Pull-down assay showed that Orf1 binds to ExoS and ExoT. Secretion profile analysis showed that Orf1 was necessary for the optimal secretion of ExoS and ExoT. However, Orf1 had no effect on the expression of exoS. Orf1 is important for the secretion of ExoS probably by maintaining ExoS in a secretion-competent conformation. We propose to name Orf1 as SpcS for "specific Pseudomonas chaperone for ExoS".


Da-Kang Shen, Lauriane Quenee, Mariette Bonnet, Lauriane Kuhn, Madiha Derouazi, Daniele Lamotte, Bertrand Toussaint, Benoit Polack. Orf1/SpcS chaperones ExoS for type three secretion by Pseudomonas aeruginosa. Biomedical and environmental sciences : BES. 2008 Apr;21(2):103-9

Expand section icon Mesh Tags

Expand section icon Substances

PMID: 18548848

View Full Text