LipC, a second lipase of Pseudomonas aeruginosa, is LipB and Xcp dependent and is transcriptionally regulated by pilus biogenesis components

We have isolated cosmids that complement a Pseudomonas aeruginosa export-impaired mutant by increasing growth on lipid agar, a medium that requires lipase expression and export. These cosmids encode a previously unidentified lipase, LipC, which has high homology to the P. aeruginosa lipA gene product. Like LipA, LipC activity requires the chaperone activity of the lipB gene product and a functional rep gene cluster for export, However, expression of LipC is barely detectable in a wild-type background. Transposan insertions that increase lipC promoter activity have been obtained that inactivate two pilus biogenesis genes, pilX and pilY1, This suggests that these proteins either directly or indirectly repress the expression of LipC and may be involved in transducing an extracellular signal that regulates this lipase.