TGME49_295340

TGME49_295340 (RAD23) is a UBL-UBA shuttle protein that operates within the ubiquitin-proteasome system of Toxoplasma gondii, escorting ubiquitinylated proteins to the proteasome for degradation (PMID:32808330). It localizes to both the cytoplasm and nucleus (PMID:32808330). Deletion of RAD23, carried out together with DDI1 and DSK2 in a triple-gene knockout, caused accumulation of ubiquitinylated proteins, inhibited parasite growth, and produced asynchronous cell division (PMID:32808330). Because RAD23 was disrupted only as part of this triple knockout, its individual contribution to these phenotypes has not been isolated in the available corpus.

1. 2020 Medium

   Establishing whether RAD23 participates in proteasomal targeting in T. gondii, the finding showed it is a cytoplasmic and nuclear UBL-UBA shuttle protein whose loss impairs clearance of ubiquitinylated proteins, tying it to the parasite's protein degradation machinery.

   Evidence Gene deletion (triple KO with DDI1 and DSK2), subcellular localization, ubiquitinylated protein accumulation assay, growth and cell division phenotype analysis in T. gondii GT1

   PMID:32808330

   Open questions at the time

   • RAD23 was deleted only within a triple KO, so its individual contribution to ubiquitin accumulation, growth inhibition, and asynchronous division is not separable
   • No direct demonstration of physical interaction with the proteasome or with ubiquitinylated cargo
   • No structural or domain-level dissection of the UBL and UBA functions