The N-terminal dimerization domains of human and Drosophila CTCF have similar functionality

CTCF is the main architectural protein found in the majority of examined bilaterians. CTCFs of various organisms contain unstructured N-terminal dimerization domain (DD) along with clusters consisting of eleven zinc-finger domains of C2H2 type. The Drosophila (dCTCF) and human (hCTCF) CTCF share sequence homology only in five C2H2 domains that specifically bind to conserved 15 bp motif. By using CTCFattP(mCh) platform to introduce desired changes in the Drosophila CTCF gene, we generated a series of transgenic lines expressing dCTCF with different variants of the N-terminal domain. Our findings revealed that the functionality of dCTCF is significantly affected solely by the deletion of the N-terminal DD. Also, we observed a strong impact on the binding of the dCTCF mutant to chromatin upon deletion of the DD. However, chromatin binding was restored in transgenic flies expressing a chimeric CTCF protein with the DD of hCTCF. Although the chimeric protein exhibited lower expression level compared to the dCTCF variants, it efficiently bound to chromatin similar to the wild type (wt) protein. Our results suggest that one of the evolutionarily conserved function of the unstructured dimerization domain is to recruit dCTCF to its binding sites in vivo. Overall design: ChIP-seq signal of the dCTCF and CP190 proteins occupancy in dCTCFwt-HA, dCTCF?80-170-HA, dCTCF?132-170-HA and dCTCFhN lines. Please note that processed data file generated from both replicates is linked to the corresponding *_1 sample records.