Peculiarities of host cholesterol transport to the unique intracellular vacuole containing Toxoplasma.
The intracellular protozoan Toxoplasma gondii is auxotrophic for low-density lipoprotein (LDL)-derived cholesterol (C). We previously showed that T. gondii scavenges this essential lipid from host endolysosomal compartments and that C delivery to the parasitophorous vacuole (PV) does not require transit through host Golgi or endoplasmic reticulum. In this study, we explore the itinerary of C from the host endolysosomes to the PV. Labeled C incorporated into LDL is rapidly detected in intravacuolar parasites and partially esterified by the parasites. In contrast to diverse mammalian organelles, the post-endolysosomal transfer of C to the PV does not involve the host plasma membrane as an intermediate. Nevertheless, the PV membrane is accessible to extracellular sterol acceptors, suggesting C trafficking from intracellular parasites to host plasma membrane. C movement to the PV requires temperatures permissive for vesicular transport, metabolic energy and functional microtubules. Host caveolae vesicles and the sterol carrier protein-2 do not participate in this process. Proteolytic treatment of purified PV or free parasites abolishes C acquisition by the parasites. Altogether, these results support a vesicular transport system from host endolysosomes to the PV, and a requirement for PV membrane and parasite plasma membrane proteins in C delivery to T. gondii.
Sehgal
Alfica
A
Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
Bettiol
Silvana
S
Pypaert
Marc
M
Wenk
Markus R
MR
Kaasch
Achim
A
Blader
Ira J
IJ
Joiner
Keith A
KA
Coppens
Isabelle
I
D000818:Animals; D002352:Carrier Proteins / Q000502:physiology; D051242:Caveolin 1 / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000378:metabolism*; D002788:Cholesterol Esters / Q000378:metabolism; D008078:Cholesterol, LDL / Q000378:metabolism; D020869:Gene Expression Profiling; D014122:Toxoplasma; D014123:Toxoplasmosis / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism* / Q000469:parasitology*; D014709:Vero Cells
D002352:Carrier Proteins; D051242:Caveolin 1; D002788:Cholesterol Esters; D008078:Cholesterol, LDL; C072087:sterol carrier proteins; D002784:Cholesterol