ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa

version 3 (curated until May 28, 2011)

Identification of trafficking determinants for polytopic rhomboid proteases in Toxoplasma gondii.

Sheiner, L., Dowse, T. J., Soldati-Favre, D. (2008 May, Traffic)

Rhomboids (ROMs) constitute a family of polytopic serine proteases conserved throughout evolution. The obligate intracellular parasite Toxoplasma gondii possesses six genes coding for ROM-like proteases that are targeted to distinct subcellular compartments: TgROM1 localizes to regulated secretory organelles, micronemes, TgROM2 is present in the Golgi, while TgROM4 and TgROM5 are found in the pellicle of the parasite. The targeting mechanism/s of ROM proteins is an aspect that has not yet been assessed. The existence of TgROM family members localized to different subcellular compartments provides a convenient system to study their sorting mechanisms in a genetically tractable organism that possesses an elaborate secretory pathway and conserved trafficking machineries. In this study, we experimentally established the topology of TgROM1 and TgROM4 at the plasma membrane and applied domain-exchange and site-directed mutagenesis approaches to identify critical sorting determinants on the N-terminal cytosolic domains of TgROM2 and TgROM1 that confer their Golgi and post-Golgi localizations, respectively.

PubMed: 18346213, full text

Localisation information

TGME49_068590 (ROM4) rhomboid-like protease 4

Experimental localisation: parasite plasma membrane during intracellular tachyzoite, parasite plasma membrane during extracellular tachyzoite, not inner membrane complex during intracellular tachyzoite, not inner membrane complex during extracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "These observations confirmed that TgROM4 localizes to the PM and validated the topology prediction."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein, Ty tag
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: PM and not IMC during intracellular tachyzoite and extracellular tachyzoite

TGME49_063290 (ROM2) rhomboid-like protease TgROM2

Experimental localisation: golgi apparatus during tachyzoite, trans-golgi network during tachyzoite, parasite plasma membrane during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "The localization of R2NtR4 NtTy is in close proximity to but do not overlap perfectly with GRASP-YFP, suggesting that the chimera accumulates in the Trans Golgi Network (TGN) recently defined with TgGalNac marker (51). These results are in agreement with the previously reported localization for TgROM2 (24) and provide the first evidence that R2Nt is sufficient to confer Golgi localization to related ROM proteins that are normally targeted to the micronemes or to the PM. In order to identify a sorting motif within R2Nt independently of the rest of the protein, the R2NtR21TMGFPTy fusion was constructed (Figureļ¾ 7)."
  • Microscopy type: Light
  • Microscopy method: Ty tag
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: Golgi and TGN and PM during tachyzoite

TGME49_000290 (ROM1) rhomboid family domain-containing protein

Experimental localisation: endoplasmic reticulum during intracellular tachyzoite, golgi apparatus during intracellular tachyzoite, rhoptry during intracellular tachyzoite, post golgi compartment during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "In transiently transfected parasites, R1NtR5 NtTy localized to the ER, Golgi and also to the apical organelle, rhoptries (Figure S2A), residents of which were shown to posses sorting signals directing anterograde trafficking from the Golgi."
  • Microscopy type: Light
  • Microscopy method: Ty tag
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: ER and golgi and rhoptries and post golgi compartment during intracellular tachyzoite

TGME49_008030 (MIC4, MIC 4) microneme protein MIC4

Experimental localisation: microneme during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "In stable parasite lines, R1NtR5 NtTy only showed accumulation to an apical compartment exhibiting partial colocalization with a typical microneme marker (TgMIC4) but mainly concentrated in a post-Golgi compartment (Figureļ¾ 6B)"
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein
  • Strain: RH hxgprt-
  • Gene model mapping comments: inferred from another publication
  • Localisation record: microneme during tachyzoite