The Major Outer Membrane Protein Oprf is Required for Rhamnolipid Production in Pseudomonas aeruginosa

Summary The OprF porin is the major outer membrane protein of bacteria belonging to the Pseudomonas genus, and is partially exposed on the cellular surface. A study based on the comparison between P. aeruginosa H103 and its oprFdeficient mutant led to the finding that the absence of OprF abolished swarming but not swimming and twitching motilities. These phenotypes were explained at least in part by the inability of the oprF mutant to produce biosurfactant rhamnolipids. The levels of mRNAs encoding the rhamnolipid biosynthetic enzymes RhlA and RhlB were strongly decreased in the absence of OprF, indicating that rhamnolipid production was impaired at the transcriptional level. We suggest that the presence of OprF in the outer membrane of P. aeruginosa is required for environments colonization, making thus OprF a serious target for limiting P. aeruginosa spreading in case of cystic fibrosis.