Identification of proteins interacting with Toxoplasma SRCAP by yeast two-hybrid screening.

Toxoplasma gondii is an opportunistic protozoan parasite that differentiates into latent cysts (bradyzoite) that can be reactivated during immunosuppression. TgSRCAP (Toxoplasma gondii Snf2-related CBP activator protein) is a SWI2/SNF2 family chromatin remodeler whose expression increases during cyst development. Identifying the proteins associating with TgSRCAP during the pre-cyst stage (tachyzoite) will increase our understanding of how parasite differentiation is initiated. We employed the yeast two-hybrid system to identify proteins that may interact directly with TgSRCAP. A stretch of 1,060 amino acids between ATPase subdomains IV and V of TgSRCAP was chosen as "bait" since the corresponding region in human SRCAP interacts with other proteins, including CREB binding protein. We have identified several novel parasite-specific transcription factors predicted to be in the T. gondii genome. Metabolic enzymes that may participate in cyst development were also identified as interacting with TgSRCAP.