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Article

  • The EMBO Journal (2006) 25, 4503 - 4512
  • doi:10.1038/sj.emboj.7601340

Published online: 21 September 2006

Solution structure of the nonmethyl-CpG-binding CXXC domain of the leukaemia-associated MLL histone methyltransferase

Mark D Allen1,a, Charles G Grummitt1,a, Christine Hilcenko2,a, Sandra Young Min2,a, Louise M Tonkin2, Christopher M Johnson1, Stefan M Freund1, Mark Bycroft1 and Alan J Warren2,3

  1. Centre for Protein Engineering, Cambridge, UK
  2. MRC Laboratory of Molecular Biology, Cambridge, UK
  3. Department of Haematology, University of Cambridge, Cambridge, UK

Correspondence to:

Alan J Warren, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK. Tel: +44 1223 252 937; Fax: +44 1223 412 178; E-mail: ajw@mrc-lmb.cam.ac.uk

aThese authors contributed equally to the work

Received 28 February 2006; Accepted 21 August 2006

Methylation of CpG dinucleotides is the major epigenetic modification of mammalian genomes, critical for regulating chromatin structure and gene activity. The mixed-lineage leukaemia (MLL) CXXC domain selectively binds nonmethyl-CpG DNA, and is required for transformation by MLL fusion proteins that commonly arise from recurrent chromosomal translocations in infant and secondary treatment-related acute leukaemias. To elucidate the molecular basis of nonmethyl-CpG DNA recognition, we determined the structure of the human MLL CXXC domain by multidimensional NMR spectroscopy. The CXXC domain has a novel fold in which two zinc ions are each coordinated tetrahedrally by four conserved cysteine ligands provided by two CGXCXXC motifs and two distal cysteine residues. We have identified the CXXC domain DNA binding interface by means of chemical shift perturbation analysis, cross-saturation transfer and site-directed mutagenesis. In particular, we have shown that residues in an extended surface loop are in close contact with the DNA. These data provide a template for the design of specifically targeted therapeutics for poor prognosis MLL-associated leukaemias.

  • Keywords:

    • chromatin,
    • CpG dinucleotide,
    • CXXC domain,
    • methylation,
    • mixed lineage leukaemia