The C-terminal amphipathic alpha-helix of Pseudomonas aeruginosa PelC outer membrane protein is required for its function

Pseudomonas aeruginosa is an opportunistic pathogen, which causes numerous infections and can adopt a versatile lifestyle. During chronic infection, P. aeruginosa becomes established as a bacterial community known as a biofilm. Biofilm formation results from the production of a matrix mainly comprised of exo-polysaccharides. P. aeruginosa possesses several gene clusters which contribute to the formation of the matrix, including the pet genes. Among the pel genes, pelC encodes an outermembrane protein, which may serve as a transporter of polysaccharide to the bacterial cell surface. Whereas outer membrane proteins usually display an amphipathic P-barrel fold, we show that PelC requires a C-terminal amphipathic a-helix for outer membrane insertion and function. Such a structural feature has only previously been reported for the Wza outer membrane protein of Escherichia coli, and our data suggest that this characteristic may be found in a large family of proteins, particularly outer membrane proteins specialized in polysaccharide transport. (C) 2009 Elsevier Masson SAS. All rights reserved.