The moving junction of apicomplexan parasites: a key structure for invasion

Abstract

SummaryMost Apicomplexa are obligate intracellular parasites and many are important pathogens of human and domestic animals. For a successful cell invasion, they rely on their own motility and on a firm anchorage to their host cell, depending on the secretion of proteins and the establishment of a structure called the moving junction (MJ). The MJ moves from the apical to the posterior end of the parasite, leading to the internalization of the parasite into a parasitophorous vacuole. Based on recent data obtained in Plasmodium and Toxoplasma, an emerging model emphasizes a cooperative role of secreted parasitic proteins in building the MJ and driving this crucial invasive process. More precisely, the parasite exports the microneme protein AMA1 to its own surface and the rhoptry neck RON2 protein as a receptor inserted into the host cell together with other RON partners. Ongoing and future research will certainly help refining the model by characterizing the molecular organization within the MJ and its interactions with both host and parasite cytoskeleton for anchoring of the complex.

Structural and functional dissection of Toxoplasma gondii armadillo repeats only protein

“…During parasite entry, only one of the 10-12 rhoptries injects its contents, including the rhoptry neck proteins (RONs), rhoptry bulb proteins (ROPs) and some membranous materials, into the host cell (Boothroyd and Dubremetz, 2008). Several RONs form a complex with apical membrane antigen 1 (AMA-1), a protein secreted from the micronemes, resulting in the formation of the so-called moving junction (Besteiro et al, 2011;Straub et al, 2009). The moving junction is a tight apposition between the parasite and the host cell plasma membrane, and ensures efficient propulsion of the parasite into the host cell, ultimately leading to the formation of the PVM (Besteiro et al, 2011;Straub et al, 2009).…”

“…Several RONs form a complex with apical membrane antigen 1 (AMA-1), a protein secreted from the micronemes, resulting in the formation of the so-called moving junction (Besteiro et al, 2011;Straub et al, 2009). The moving junction is a tight apposition between the parasite and the host cell plasma membrane, and ensures efficient propulsion of the parasite into the host cell, ultimately leading to the formation of the PVM (Besteiro et al, 2011;Straub et al, 2009). Several ROPs migrate either to the lumen of the nascent parasitophorous vacuole, the PVM, or into the cytosol or nucleus of the infected host cell where they modulate cellular functions (Butcher et al, 2011;El Hajj et al, 2007a;Etheridge et al, 2014;Fleckenstein et al, 2012;Yamamoto et al, 2009).…”

Functional Dissection of Toxoplasma gondii Perforin-like Protein 1 Reveals a Dual Domain Mode of Membrane Binding for Cytolysis and Parasite Egress

“…These microorganisms have a unique set of apical secretory organelles termed micronemes and rhoptries. Proteins secreted from these organelles are involved in parasite gliding motility, cell invasion, and manipulation of the host cell to protect the intracellular replication compartment, the parasitophorous vacuole (15)(16)(17)(18). Thus, the majority of characterized secretory proteins function at the point of cell entry.…”

A Conserved Apicomplexan Microneme Protein Contributes to Toxoplasma gondii Invasion and Virulence

“…Principal among these features are an apical complex, invasion-related secretory organelles, and modes of motility and invasion (3)(4)(5). Invasion, consisting of attachment and penetration, involves a coordinated sequential secretion of proteins from secretory organelles termed micronemes, rhoptries, and dense granules (5,6).…”