Molecular partitioning during host cell penetration by Toxoplasma gondii.
During invasion by Toxoplasma gondii, host cell transmembrane proteins are excluded from the forming parasitophorous vacuole membrane (PVM) by the tight apposition of host and parasite cellular membranes. Previous studies suggested that the basis for the selective partitioning of membrane constituents may be a preference for membrane microdomains, and this hypothesis was herein tested. The partitioning of a diverse group of molecular reporters for raft and nonraft membrane subdomains was monitored during parasite invasion by time-lapse video or confocal microscopy. Unexpectedly, both raft and nonraft lipid probes, as well as both raft and nonraft cytosolic leaflet proteins, flowed unhindered past the host-parasite junction into the PVM. Moreover, neither a raft-associated type 1 transmembrane protein nor its raft-dissociated counterpart accessed the PVM, while a multispanning membrane raft protein readily did so. Considered together with previous data, these studies demonstrate that selective partitioning at the host-parasite interface is a highly complex process, in which raft association favors, but is neither necessary nor sufficient for, inclusion into the T. gondii PVM.
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Audra J
AJ
Charron
L David
LD
Sibley
D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D004396:Coloring Agents / Q000494:pharmacology; D006224:Cricetinae; D003600:Cytosol / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008055:Lipids / Q000737:chemistry; D021962:Membrane Microdomains / Q000378:metabolism / Q000469:parasitology; D018613:Microscopy, Confocal; D018715:Microscopy, Video; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017830:Octoxynol / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014122:Toxoplasma / Q000378:metabolism* / Q000472:pathogenicity; D014162:Transfection
D004396:Coloring Agents; D003902:Detergents; D008055:Lipids; D049452:Green Fluorescent Proteins; D017830:Octoxynol