PelC is a Pseudomonas aeruginosa outer membrane lipoprotein of the OMA family of proteins involved in exopolysaccharide transport

Pseudomonas aeruginosa is a gram-negative bacterium, opportunistic pathogen, which causes severe acute or chronic infections, as is the case with cystic fibrosis patients. Chronic infections are frequently accompanied by the development of the bacterial population into a specialized community called biofilm. The pe1A-G gene cluster of P. aeruginosa has been shown to be involved in pellicle production and biofilm formation. The Pe1 genes have been proposed to contribute to the formation of the exopolysaccharide-containing Pe1licle. However, the function and the subcellular localization of the seven different Pe1 proteins are poorly understood. Based on bioinformatics analysis, we have previously considered that Pe1F is a putative glycosyltransferase (GT4 family), whereas Pe1G is a Wzx-like polysaccharide transporter from the PST family. In this study we have further characterized the Pe1C protein. We have shown that Pe1C is an outer membrane lipoprotein. The N-terminal signal peptide of the Pe1C lipoprotein is sufficient to target the protein into the membranes. However, by constructing various Pe1C hybrid proteins we also proposed that efficient and functional outer membrane insertion of Pe1C requires not only the signal peptide and the lipid modification, but also requires the C-terminal domain of Pe1C. Because the gene encoding the outer membrane lipoprotein Pe1C is part of a putative gene cluster involved in exopolysaccharide biogenesis, we suggest that Pe1C is a new member of the outer membrane auxiliary (OMA) family of lipoprotein whose Wza, involved in Escherichia coli capsular polysaccharide transport, is an archetype. (c) 2007 Elsevier Masson SAS. All rights reserved.