Ability of whole Borrelia lipid extracts and individual Borrelia lipids to form vesicles with ordered-state bilayers as assayed by FRET. (A) Whole lipid extracts from B. burgdorferi strain B31 (diamonds), B. burgdorferi strain B313 (squares), and B. hermsii (triangles). DOPC (circles) is shown for comparison. (B) Individual lipids ACGal (diamonds), B. burgdorferi PC (triangles), and DOPC (circles). F/Fo is the ratio of fluorescence in vesicles with donor (0.1 mol % pyrene-DPPE) and acceptor (5 mol % rhod-DOPE) to that in vesicles containing only acceptor, after background values were subtracted. The average and standard deviation from three samples are shown.