4f6n
From Proteopedia
Crystal structure of Kaiso zinc finger DNA binding protein in complex with methylated CpG site DNA
Structural highlights
Function[KAISO_HUMAN] Transcriptional regulator with bimodal DNA-binding specificity. Binds to methylated CpG dinucleotides in the consensus sequence 5'-CGCG-3' and also binds to the non-methylated consensus sequence 5'-CTGCNA-3'. Recruits the N-CoR repressor complex to promote histone deacetylation and the formation of repressive chromatin structures in target gene promoters. May contribute to the repression of target genes of the Wnt signaling pathway. May also activate transcription of a subset of target genes by the recruitment of CTNND2.[1] [2] [3] [4] Publication Abstract from PubMedMethylation of CpG dinucleotides in DNA is a common epigenetic modification in eukaryotes that plays a central role in maintenance of genome stability, gene silencing, genomic imprinting, development, and disease. Kaiso, a bifunctional Cys(2)His(2) zinc finger protein implicated in tumor-cell proliferation, binds to both methylated CpG (mCpG) sites and a specific nonmethylated DNA motif (TCCTGCNA) and represses transcription by recruiting chromatin remodeling corepression machinery to target genes. Here we report structures of the Kaiso zinc finger DNA-binding domain in complex with its nonmethylated, sequence-specific DNA target (KBS) and with a symmetrically methylated DNA sequence derived from the promoter region of E-cadherin. Recognition of specific bases in the major groove of the core KBS and mCpG sites is accomplished through both classical and methyl CH...O hydrogen-bonding interactions with residues in the first two zinc fingers, whereas residues in the C-terminal extension following the third zinc finger bind in the opposing minor groove and are required for high-affinity binding. The C-terminal region is disordered in the free protein and adopts an ordered structure upon binding to DNA. The structures of these Kaiso complexes provide insights into the mechanism by which a zinc finger protein can recognize mCpG sites as well as a specific, nonmethylated regulatory DNA sequence. Molecular basis for recognition of methylated and specific DNA sequences by the zinc finger protein Kaiso.,Buck-Koehntop BA, Stanfield RL, Ekiert DC, Martinez-Yamout MA, Dyson HJ, Wilson IA, Wright PE Proc Natl Acad Sci U S A. 2012 Sep 4. PMID:22949637[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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