PMID:20421941

Citation	Buguliskis, JS, Brossier, F, Shuman, J and Sibley, LD (2010) Rhomboid 4 (ROM4) affects the processing of surface adhesins and facilitates host cell invasion by Toxoplasma gondii. PLoS Pathog. 6:e1000858
Abstract	Host cell attachment by Toxoplasma gondii is dependent on polarized secretion of apical adhesins released from the micronemes. Subsequent translocation of these adhesive complexes by an actin-myosin motor powers motility and host cell invasion. Invasion and motility are also accompanied by shedding of surface adhesins by intramembrane proteolysis. Several previous studies have implicated rhomboid proteases in this step; however, their precise roles in vivo have not been elucidated. Using a conditional knockout strategy, we demonstrate that TgROM4 participates in processing of surface adhesins including MIC2, AMA1, and MIC3. Suppression of TgROM4 led to decreased release of the adhesin MIC2 into the supernatant and concomitantly increased the surface expression of this and a subset of other adhesins. Suppression of TgROM4 resulted in disruption of normal gliding, with the majority of parasites twirling on their posterior ends. Parasites lacking TgROM4 bound better to host cells, but lost the ability to apically orient and consequently most failed to generate a moving junction; hence, invasion was severely impaired. Our findings indicate that TgROM4 is involved in shedding of micronemal proteins from the cell surface. Down regulation of TgROM4 disrupts the normal apical-posterior gradient of adhesins that is important for efficient cell motility and invasion of host cells by T. gondii.
Links	PubMed PMC2858701 Online version:10.1371/journal.ppat.1000858
Keywords	Antigens, Protozoan/metabolism; Cell Separation; Cells, Cultured; Fibroblasts/parasitology; Flow Cytometry; Gene Knockout Techniques; Host-Parasite Interactions/physiology; Humans; Membrane Proteins/metabolism; Microscopy, Fluorescence; Protozoan Proteins/genetics; Protozoan Proteins/metabolism; Reverse Transcriptase Polymerase Chain Reaction; Toxoplasma/metabolism; Toxoplasma/pathogenicity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
TOXGO:RHBL4		GO:0030260: entry into host cell	ECO:0000315:		P		Figure 3A. Suppression of TgROM4 results in impaired invasion of host cells	complete CACAO 5927
TOXGO:RHBL4		GO:0060352: cell adhesion molecule production	ECO:0000315:		P		Figure 7B. Shedding of MIC2 into the supernatant is decreased in the TgROM4 conditional knockout.	complete CACAO 5928
TOXGO:RHBL4	involved_in	GO:0030260: entry into host cell	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
TOXGO:RHBL4	involved_in	GO:0060352: cell adhesion molecule production	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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