Lipase LipC Affects Motility, Biofilm Formation and Rhamnolipid Production in Pseudomonas Aeruginosa

Pseudomonas aeruginosa produces and secretes several lipolytic enzymes, among them the lipases LipA and LipC. LipA is encoded within the lipA/lipH operon, together with its cognate foldase LipH, which was also found to be required for the functional expression of LipC. At present, the physiological function of LipC is unknown. We have cloned a synthetic operon consisting of the lipC structural gene and the foldase gene lipH obtained from the lipA/lipH operon and have constructed, in parallel, a lipC-deficient P. aeruginosa mutant. Inactivation of the lipC gene significantly impaired type IV pilus-dependent twitching and swarming motility, but also the flagella-mediated swimming motility of P. aeruginosa. Moreover, for the lipC mutant, we observed a significant decrease in the amount of extracellular rhamnolipids. Also, the P. aeruginosa lipC mutant showed a significantly altered biofilm architecture. Proteome analysis revealed the accumulation of the response regulator protein PhoP in the lipC mutant.