Discovery of RUF6 ncRNA interacting proteins involved in P. falciparum immune evasion

RUF6 is a ncRNA gene family that is transcribed by RNA Polymerase III but actively regulates the Pol II-transcribed var virulence gene family. Understanding how RUF6 ncRNA connect to downstream effectors is lacking. We developed an RNA-directed proteomic discovery (ChIRP-MS) protocol to identify in vivo RUF6 ncRNA protein interactions. The RUF6 ncRNA interactome was purified with biotinylated antisense oligonucleotides. Quantitative label-free mass spectrometry identified several unique proteins linked to gene transcription including. Affinity purification of Pf-DDX5 identified proteins originally found by our RUF6-ChIRP protocol, validating the technique’s robustness for identifying ncRNA interactomes in P. falciparum. Our work identifies a RUF6 ncRNA protein complex that interacts with RNA Pol II to sustain var gene expression.