The ICF syndrome protein CDCA7 harbors a unique DNA binding domain that recognizes a CpG dyad in the context of a non-B DNA
Swanand Hardikar, Ren Ren, Zhengzhou Ying, Jujun Zhou, J.R. Horton, Matthew D. Bramble, Bin Liu, Yue Lu, Bigang Liu, Luis Della Coletta, Jianjun Shen, Jiameng Dan, Xing Zhang, Xiaodong Cheng, Taiping Chen
Abstract
, encoding a protein with a carboxyl-terminal cysteine-rich domain (CRD), is mutated in immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome, a disease related to hypomethylation of juxtacentromeric satellite DNA. How CDCA7 directs DNA methylation to juxtacentromeric regions is unknown. Here, we show that the CDCA7 CRD adopts a unique zinc-binding structure that recognizes a CpG dyad in a non-B DNA formed by two sequence motifs. CDCA7, but not ICF mutants, preferentially binds the non-B DNA with strand-specific CpG hemi-methylation. The unmethylated sequence motif is highly enriched at centromeres of human chromosomes, whereas the methylated motif is distributed throughout the genome. At S phase, CDCA7, but not ICF mutants, is concentrated in constitutive heterochromatin foci, and the formation of such foci can be inhibited by exogenous hemi-methylated non-B DNA bound by the CRD. Binding of the non-B DNA formed in juxtacentromeric regions during DNA replication provides a mechanism by which CDCA7 controls the specificity of DNA methylation.