A Major Role for the Plasmodium falciparum ApiAP2 Protein PfSIP2 in Chromosome End Biology
Figure 5
PfSIP2-N-HA binds exclusively to SPE2 elements located in heterochromatic TARE2/3 and upsB var gene domains.
(A) PfSIP2-N-HA binds exclusively to SPE2 sites in TARE2/3 and upstream of upsB var genes. A region located between TARE2 and TARE3, the regions upstream of the only internal upsB var gene PFL0935c, promoters of five loci carrying predicted SPE2 consensus sites, and promoters of five genes lacking a SPE2 consensus site were tested by ChIP-qPCR for in vivo binding of PfSIP2-N-HA. qPCR primers were directed against upstream regions (represented by horizontal lines with arrows). Fold enrichment values represent the mean of three independent experiments on 3D7/SIP2-N-HA schizont stage samples (error bars indicate the standard deviation). 3D7 wild-type parasites were used as negative control. Gene names and accession numbers are according to PlasmoDB version5.5 (www.plasmodb.org). SPE2 elements are indicated by thick vertical black lines. (B) PfSIP2-N/SPE2 is embedded in PfHP1-containing heterochromatin. Parallel ChIP-qPCR was performed on 3D7/SIP2-N-HA/HP1-Ty schizont stage parasites using anti-HA and anti-Ty antibodies to test for occupancy by PfSIP2-N-HA and PfHP1-Ty, respectively. Normal rabbit IgG was used as negative control for ChIP. qPCR primers were directed against upstream regions (represented by horizontal lines with arrows). Vertical thick lines indicate the presence of SPE2 consensus sites. PfSIP2-N-HA and PfHP1-Ty co-occupancy at these loci was confirmed by ChIP-re-ChIP in independent experiments (Figure S4).
