How Apicomplexa Parasites Secrete and Build Their Invasion Machinery

Abstract

Apicomplexa are obligatory intracellular parasites that sense and actively invade host cells. Invasion is a conserved process that relies on the timely and spatially controlled exocytosis of unique specialized secretory organelles termed micronemes and rhoptries. Microneme exocytosis starts first and likely controls the intricate mechanism of rhoptry secretion. To assemble the invasion machinery, micronemal proteins—associated with the surface of the parasite—interact and form complexes with rhoptry proteins, which in turn are targeted into the host cell. This review covers the molecular advances regarding microneme and rhoptry exocytosis and focuses on how the proteins discharged from these two compartments work in synergy to drive a successful invasion event. Particular emphasis is given to the structure and molecular components of the rhoptry secretion apparatus, and to the current conceptual framework of rhoptry exocytosis that may constitute an unconventional eukaryotic secretory machinery closely related to the one described in ciliates. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

In vitroproduction of cat-restrictedToxoplasmapre-sexual stages by epigenetic reprogramming

“…The copyright holder for this this version posted January 17, 2023. ; https://doi.org/10.1101/2023.01. 16.524187 doi: bioRxiv preprint as shown by hierarchical clustering analyses (Fig. 1c and Supplementary Fig.…”

“…The copyright holder for this this version posted January 17, 2023. ; https://doi.org/10.1101/2023.01. 16.524187 doi: bioRxiv preprint its elongation and constriction, suggestive of replication by scission (Fig. 3c), which was also visualized by immunofluorescence with the ATrx1 antibody 26 (Extended Data Fig.…”

“…The copyright holder for this this version posted January 17, 2023. ; https://doi.org/10.1101/2023.01. 16.524187 doi: bioRxiv preprint shifted toward the pre-gametes stages, resulting in a significant over-expression of 276 proteins, whereas the expression of 285 tachyzoite proteins was suppressed after treatment (Supplementary Fig. 2c and Table 3).…”

“…The process of invasion has been thoroughly examined, revealing the cryptic functions of organelle-resident proteins, specifically in the tachyzoite stage 16 . First, micronemes secrete proteins (MICs) that function as adhesins that facilitate attachment to the host cell and thus play a key role in motility and invasion.…”

“…The copyright holder for this this version posted January 17, 2023. ; https://doi.org/10.1101/2023.01. 16.524187 doi: bioRxiv preprint 90% of the known 88 SRS were induced in IAA-treated parasites phenocopying the merozoite stage, while all tachyzoite-specific SRS were simultaneously suppressed (Supplementary Fig. 3d).…”