The Plasmodium falciparum Nuclear Protein Phosphatase NIF4 is Required for Efficient Merozoite Invasion and Regulates Artemisinin Sensitivity

ABSTRACT: Artemisinin resistance in Plasmodium falciparum, clinically presented as prolonged parasite clearance half-life, has been associated with a mutation in the NLI-interacting factor-like phosphatase PfNIF4, in addition to the mutations in the Kelch13 protein as the major determinant. We found that PfNIF4 predominant expression at the schizont stage and localized in the nuclei of the parasite. To elucidate the functions of PfNIF4 in P. falciparum, we performed PfNIF4 knockdown (KD) using the inducible ribozyme system. PfNIF4 KD attenuated merozoite invasion and affected gametocytogenesis. PfNIF4 KD parasites also showed significantly increased in vitro susceptibility to artemisinins. Transcriptomic analysis revealed that PfNIF4 KD led to significant changes in the expression of approximately 10-25% of parasite genes during the IDC. At the schizont stage, down-regulated genes were significantly enriched in the invasion-related terms, while at the trophozoite and schizont stages, pathways associated with artemisinin resistance (e.g., mitochondrial function, membrane, and Kelch13 interactome) were also down-regulated. Consistent with PfNIF4 being a protein phosphatase, PfNIF4 KD resulted in an overall up-regulation of the phosphoproteome of infected erythrocytes. Specifically, we observed increased phosphorylation of Ser2/5 of the tandem repeats in the Rpb1 C-terminal domain (CTD) of RNA polymerase II (RNAPII) upon PfNIF4 KD. Furthermore, using the TurboID-based proteomic approach, we identified that PfNIF4 interacted with the RNA polymerase II (RNAPII) components, AP2-domain transcription factors, and chromatin-modifiers and binders. These findings suggest that PfNIF4 may act as the RNAPII CTD phosphatase, regulating the expression of general and parasite-specific cellular pathways during the blood-stage development.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Plasmodium Falciparum (isolate 3d7)

TISSUE(S): Blood

SUBMITTER: Xiaotong Zhu  

LAB HEAD: Xiaotong Zhu

PROVIDER: PXD033957 | Pride | 2022-07-23

REPOSITORIES: Pride