8ssq
From Proteopedia
ZnFs 3-11 of CCCTC-binding factor (CTCF) Complexed with 35mer DNA 35-4
Structural highlights
FunctionCTCF_HUMAN Chromatin binding factor that binds to DNA sequence specific sites. Involved in transcriptional regulation by binding to chromatin insulators and preventing interaction between promoter and nearby enhancers and silencers. Acts as transcriptional repressor binding to promoters of vertebrate MYC gene and BAG1 gene. Also binds to the PLK and PIM1 promoters. Acts as a transcriptional activator of APP. Regulates APOA1/C3/A4/A5 gene cluster and controls MHC class II gene expression. Plays an essential role in oocyte and preimplantation embryo development by activating or repressing transcription. Seems to act as tumor suppressor. Plays a critical role in the epigenetic regulation. Participates in the allele-specific gene expression at the imprinted IGF2/H19 gene locus. On the maternal allele, binding within the H19 imprinting control region (ICR) mediates maternally inherited higher-order chromatin conformation to restrict enhancer access to IGF2. Plays a critical role in gene silencing over considerable distances in the genome. Preferentially interacts with unmethylated DNA, preventing spreading of CpG methylation and maintaining methylation-free zones. Inversely, binding to target sites is prevented by CpG methylation. Plays a important role in chromatin remodeling. Can dimerize when it is bound to different DNA sequences, mediating long-range chromatin looping. Mediates interchromosomal association between IGF2/H19 and WSB1/NF1 and may direct distant DNA segments to a common transcription factory. Causes local loss of histone acetylation and gain of histone methylation in the beta-globin locus, without affecting transcription. When bound to chromatin, it provides an anchor point for nucleosomes positioning. Seems to be essential for homologous X-chromosome pairing. May participate with Tsix in establishing a regulatable epigenetic switch for X chromosome inactivation. May play a role in preventing the propagation of stable methylation at the escape genes from X- inactivation. Involved in sister chromatid cohesion. Associates with both centromeres and chromosomal arms during metaphase and required for cohesin localization to CTCF sites. Regulates asynchronous replication of IGF2/H19.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Publication Abstract from PubMedThe CCCTC-binding factor (CTCF) binds tens of thousands of enhancers and promoters on mammalian chromosomes by means of its 11 tandem zinc finger (ZF) DNA-binding domain. In addition to the 12-15-bp CORE sequence, some of the CTCF binding sites contain 5' upstream and/or 3' downstream motifs. Here, we describe two structures for overlapping portions of human CTCF, respectively, including ZF1-ZF7 and ZF3-ZF11 in complex with DNA that incorporates the CORE sequence together with either 3' downstream or 5' upstream motifs. Like conventional tandem ZF array proteins, ZF1-ZF7 follow the right-handed twist of the DNA, with each finger occupying and recognizing one triplet of three base pairs in the DNA major groove. ZF8 plays a unique role, acting as a spacer across the DNA minor groove and positioning ZF9-ZF11 to make cross-strand contacts with DNA. We ascribe the difference between the two subgroups of ZF1-ZF7 and ZF8-ZF11 to residues at the two positions -6 and -5 within each finger, with small residues for ZF1-ZF7 and bulkier and polar/charged residues for ZF8-ZF11. ZF8 is also uniquely rich in basic amino acids, which allows salt bridges to DNA phosphates in the minor groove. Highly specific arginine-guanine and glutamine-adenine interactions, used to recognize G:C or A:T base pairs at conventional base-interacting positions of ZFs, also apply to the cross-strand interactions adopted by ZF9-ZF11. The differences between ZF1-ZF7 and ZF8-ZF11 can be rationalized structurally and may contribute to recognition of high-affinity CTCF binding sites. Structures of CTCF-DNA complexes including all 11 zinc fingers.,Yang J, Horton JR, Liu B, Corces VG, Blumenthal RM, Zhang X, Cheng X Nucleic Acids Res. 2023 Jul 13:gkad594. doi: 10.1093/nar/gkad594. PMID:37439339[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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