PfMORC modulates gene expression through interactions with heterochromatin in Plasmodium falciparum

Dynamic control of gene expression is critical for blood stage development of malaria parasites. Here, we used multi-omic analyses to investigate transcriptional regulation by the chromatin-associated microrchidia protein, PfMORC, during asexual blood stage development of the human malaria parasite Plasmodium falciparum. PfMORC (PF3D7_1468100) interacts with a suite of nuclear proteins, including APETALA2 (AP2) transcription factors (PfAP2-G5, PfAP2-O5, PfAP2-I, PfAP2-MRP and PF3D7_0420300, PF3D7_0613800, and PF3D7_1239200), a DNA helicase DS60 (PF3D7_1227100), and other chromatin remodelers (PfCHD1, PfEELM2, and PfISWI). Transcriptomic analysis of PfMORCHA-glmS knockdown parasites revealed 163 differentially expressed genes belonging to hypervariable multigene families, along with upregulation of genes mostly involved in host cell invasion. In vivo genome-wide chromatin occupancy analysis during both trophozoite and schizont stages of development demonstrates that PfMORC is recruited to repressed, multigene families, including the var genes in subtelomeric chromosomal regions. Collectively, we find that PfMORC is found in chromatin complexes that play a role in the epigenetic control of asexual blood stage transcriptional regulation. Two biological replicates of chromatin immunoprecipitation followed by sequencing (ChIP-seq) was used to identify the genome-wide binding sites of chromatin-assocaited factor, PfMORC (gene ID: PF3D7_1468100), Plasmodium falciparum parasite line with a C-terminal 3xHA tag.