Extended Data Figure 9: Chromatin-associated exoribonuclease PfRNase II and plasmodial exosome have distinct functions in P. falciparum.

a, Schematic representation of the PfRNase II–HA fusion protein. b, Examination of the integration event of PfRNase II–HA transfectants by PCR with genomic DNA. c, Western blot of PfRNase II–HA line with anti-HA and anti-aldolase antibodies. d, qPCR analysis of individual var genes in two independent PfRNase II–HA clones. Samples were harvested at the ring stage. The data are shown as relative copy numbers related to the seryl-tRNA synthetase gene. e, ChIP–qPCR of PfRNase II–HA transfectant. The enrichment of distinct var-subtype var genes with anti-HA antibody is shown. Error bars represent s.e.m. for three independent experiments. f, The plasmodial exosome is expected to exert its functions as described in other eukaryotic organisms (i), whereas the additional non-exosome exoribonuclease PfRNase II has evolved as a regulator of expression of upsA-type var genes in P. falciparum (ii). The 3′–5′ exoribonuclease activity may need other helper molecules to access the 3′ end of nascent RNA. Alternatively, a potential N-terminal PIN-like domain of PfRNase II may help to degrade the nascent RNA by its endonuclease activity as described in yeast⁴². For b and c, data are representative of three independent experiments.