Uptake and transbilayer distribution of phosphatidylcholines in Mycoplasma gallisepticum and their effect on cell morphology.

Mycoplasma gallisepticum cells grown in a serum-free medium incorporated large amounts of egg-phosphatidylcholine (Egg-PC), dioleoylphosphatidylcholine (DOPC) or dipalmitoylphosphatidylcholine (DPPC) added to the growth medium. Egg-PC and DOPC were incorporated at a high rate and to a large extent and were modified by the organisms, whereas DPPC was incorporated at a lower rate and to a lesser extent and was not modified by the cells. The lactoperoxidase-mediated radioiodination applied to study the transbilayer distribution of phosphatidylcholine (PC) in the membranes revealed that the PC in cells grown with DOPC is almost equally distributed in the outer and inner leaflets of M. gallisepticum membranes, while the PC in DPPC-grown cells is preferentially located in the outer leaflet and that in Egg-PC-grown cells is found in the inner leaflet. Thus, in Egg-PC- or DPPC-grown cells the equilibrium in structure and properties between the inner and outer leaflets is disturbed, resulting in dramatic effects on the morphology of M. gallisepticum cells.