UBL-UBA Shuttle Protein DSK2s Are Important for Parasite Intracellular Replication.

() is an important human and veterinary pathogen causing life-threatening disease in immunocompromised patients. The UBL-UBA shuttle protein family are important components of the ubiquitin-proteasome system. Here, we identified a novel UBL-UBA shuttle protein DSK2b that is charactered by an N-terminal ubiquitin-like domain (UBL) and a C-terminal ubiquitin-associated domain (UBA). DSK2b was localized in the cytoplasm and nucleus. The deletion of did not affect the degradation of ubiquitinated proteins, parasite growth in vitro or virulence in mice. The double-gene knockout of and its paralogs (ΔΔ) results in a significant accumulation of ubiquitinated proteins and the asynchronous division of . The growth of ΔΔ was significantly inhibited in vitro, while virulence in mice was not attenuated. In addition, autophagy occurred in the ΔΔ which was speculated to degrade the accumulated ubiquitinated proteins in the parasites. Overall, DSK2b is a novel UBL-UBA shuttle protein contributing to the degradation of ubiquitinated proteins and is important for the synchronous cell division of