Subcellular localization of PilF and PilQ. Results of Western blot analysis of PilF, PilQ, and OprF in the sucrose gradient fractionations of wild-type P. aeruginosa strain mPAO1 (first panel), the pilF::Tn5 mutant (second panel), the pilF::Tn5 mutant complemented with PilF (+F; third panel), and the C18G lipidation mutant (fourth panel). In each panel, the inner membrane (lane 1), outer membrane fractions I and II (lanes 2 and 3), and the soluble lysate (lane 4) were analyzed.