PHOSPHOLIPID-COMPOSITION OF PURIFIED CHLAMYDIA-TRACHOMATIS MIMICS THAT OF THE EUKARYOTIC HOST-CELL

Chlamydia trachomatis is an obligate intracellular eubacterial parasit e capable of infecting a wide range of eucaryotic host cells. Purified chlamydiae contain several lipids typically found in eucaryotes, and it has been established that eucaryotic lipids are transported from th e host cell to the parasite. In this report, we examine the phospholip id composition of C. trachomatis purified from host cells grown under a variety of conditions in which the cellular phospholipid composition was altered. A mutant CHO cell line, with a thermolabile CDP-choline synthetase, was used to show that decreased host cell phosphatidylchol ine levels had no significant effect on C. trachomatis growth. However , less phosphatidylcholine was transported to the parasite and purifie d elementary bodies contained decreased levels of phosphatidylcholine. Brefeldin A, fumonisin B-1,, and exogenous sphingomyelinase were used to alter levels of host cell sphingomyelin, None of the agents had a significant effect on C. trachomatis replication. Treatment with fumon isin B-1, and exogenous sphingomyelinase resulted in decreased levels of host cell sphingomyelin, This had no effect on glycerophospholipid trafficking to chlamydiae; however, sphingomyelin trafficking was redu ced and elementary bodies purified from treated cells had reduced sphi ngomyelin content. Exposure to brefeldin A, which had no adverse effec t on chlamydia growth, resulted in an increase in cellular levels of s phingomyelin and a concomitant increase in the amount of sphingomyelin in purified chlamydiae. Under the experimental conditions used, brefe ldin A treatment had only a small effect on sphingomyelin trafficking to the host cell surface or to C, trachomatis, Thus, the final phospho lipid composition of purified C. trachomatis mimics that of the host c ell in which it is grown.