A human DNA-binding protein is methylation-specific and sequence-specific

Abstract

A nuclear protein isolated from human placenta, methylated DNA-binding protein (MDBP), binds selectively to DNA enriched in 5-methylcytosine. We now demonstrate that MDBP is a sequence-specific, as well as methylation-specific, DNA-binding protein. From ten restriction fragments of pBR322 DNA methylated with human DNA methyltransferase, one was bound to MDBP very much more strongly than any of the others. For this preferential binding to MDBP, the DNA had to be methylated. By a DNase I protection experiment (DNase I footprinting), a 22-base sequence within this methylated restriction fragment was shown to be specifically protected by MDBP. The sequence-specificity of MDBP coupled with its dependence on DNA methylation suggests that this is one of the proteins which modulates important functions of human DNA methylation in vivo.

Characterization of MeCP2, a vertebrate DNA binding protein with affinity for methylated DNA

“…Neither hemi-methylated DNA molecules nor DNA molecules containing m5C in a non-CpG context are good substrates for MeCPI and MeCP2. Two other proteins that bind to methylated DNA have also been identified, but they differ from MeCPI and -2 in that methylcytosine must be part of a specific recognition sequence for binding to occur (9,10). In this paper we demonstrate that MeCPI and MeCP2 are two distinct activities, and show biochemical evidence that MeCP2 is associated with chromatin.…”

Demethylation enhances removal of pyrimidine dimers from the overall genome and from specific DNA sequences in Chinese hamster ovary cells.

“…That chromatin structure can indeed interfere with DNA repair has been demonstrated previously (20). Also, a putative methylated DNA-binding protein has been partially purified from human placental nuclei (54), and binding-substrate experiments reveal that the dinucleotide CpG in its methylated state is necessary but not sufficient for its binding (12,55).…”

The g.1170C>T polymorphism of the 5′ untranslated region of the human alpha‐galactosidase gene is associated with decreased enzyme expression—Evidence from a family study

“…2), which is possibly involved in the repression or attenuation of gene transcription, both through cytosine methylation-dependent or independent modes (Khan et al 1988;Wang et al 1986). In the human cytomegalovirus, the substitution of thymine for cytosine in the third position of a consensus Fig.…”