LIPID-METABOLISM IN CHLAMYDIA TRACHOMATIS-INFECTED CELLS - DIRECTED TRAFFICKING OF GOLGI-DERIVED SPHINGOLIPIDS TO THE CHLAMYDIAL INCLUSION

Chlamydia trachomatis undergoes its entire life cycle within an unchar acterized intracellular vesicle that does not fuse with lysosomes, We used a fluorescent Golgi-specific probe, obenzo-2-oxa-1,3-diazole)]}am inocaproylsphingosine (C-6-NBD-Cer), in conjunction with conventional fluorescence or confocal microscopy to identify interactions between t he Golgi apparatus and the chlamydial inclusion, We observed not only a close physical association between the Golgi apparatus and the chlam ydial inclusion but the eventual presence of a metabolite of this fluo rescent probe associated with the chlamydiae themselves, Sphingomyelin , endogenously synthesized from C-6-NBD-Cer, was specifically transpor ted to the inclusion and incorporated into the cell wall of the intrac ellular chlamydiae, Incorporation of the fluorescent sphingolipid by c hlamydiae was inhibited by brefeldin A. Chlamydiae therefore occupy a vesicle distal to the Golgi apparatus that receives anterograde vesicu lar traffic from the Golgi normally bound for the plasma membrane, Col lectively, the data suggest that the chlamydial inclusion may represen t a unique compartment within the trans-Golgi network.