Methyl CpG binding proteins: coupling chromatin architecture to gene regulation.

A correlation between DNA methylation and transcriptional silencing has existed for many years. Recently, substantial progress has been reported in the search for proteins that interpret the regulatory information inherent in DNA methylation and translate this information into functional states, resulting in the identification of a family of highly conserved proteins, the MBD family. Direct connections between these proteins and histone modification enzymes have emerged as a common theme, implying that DNA methylation exerts its effects primarily through repressive chromatin architecture. Recent structural determinations of the DNA binding domain of two MBD family members, MeCP2 and MBD1, provide a framework to model the interactions of this family with DNA. Comparative sequence analysis and experimental DNA binding data can be interpreted using this structural framework allowing one to contrast the members of the MBD family with each other and to predict the properties of new family members. The identification of mutations in MeCP2, the founding member of this family, as causal for the neurological developmental disorder Rett Syndrome provides additional information regarding amino acid residues crucial to the functions of this interesting protein family.