Rapid invasion of host cells by Toxoplasma requires secretion of the MIC2-M2AP adhesive protein complex.
Vertebrate cells are highly susceptible to infection by obligate intracellular parasites such as Toxoplasma gondii, yet the mechanism by which these microbes breach the confines of their target cell is poorly understood. While it is thought that Toxoplasma actively invades by secreting adhesive proteins from internal organelles called micronemes, no genetic evidence is available to support this contention. Here, we report successful disruption of M2AP, a microneme protein tightly associated with an adhesive protein called MIC2. M2AP knockout parasites were >80% impaired in host cell entry. This invasion defect was likely due to defective expression of MIC2, which partially accumulated in the parasite endoplasmic reticulum and Golgi. M2AP knockout parasites were also unable to rapidly secrete MIC2, an event that normally accompanies parasite attachment to a target cell. These findings indicate a critical role for the MIC2-M2AP protein complex in parasite invasion.
W Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
My-Hang
MH
Huynh
Karen E
KE
Rabenau
Jill M
JM
Harper
Wandy L
WL
Beatty
L David
LD
Sibley
Vern B
VB
Carruthers
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D014122:Toxoplasma / Q000472:pathogenicity*
D017931:DNA Primers; C408878:MIC2 protein, Toxoplasma gondii; D008565:Membrane Proteins; D015800:Protozoan Proteins