Methylated DNA-binding protein from human placenta recognizes specific methylated sites on several prokaryotic DNAs

Abstract

Methylated DNA-binding protein (MDBP) from human placement recognizes specific DNA sequences containing 5-methylcytosine (m5c) residues. Comparisous of binding of various prokaryotic DNAs to MDBP indicate that m5CpG is present in the recognition sites for this protein but is only part of the recognition sequence. Specific binding to MDBP was observed for bacteriophage XP12 DNA, which naturally contains ∼/3 of its residues as m5C, and for Micrococcus luteus DNA, M13mp8 replicative form (RF) DNA, and pBR322 when these three DNAs were methylated at CpG sites by human DNA methyltransferense. Five DNA regions binding to MDBP have been localized by DNase I footprinting or restriction mapping in methylated pBR322 and M13mp8 RF DNAs. A comparison of their sequences reveals a common 5'-m5CGRm5CG-3' element or closely related sequence in which one of the m5residues may be replaced by a T. In addition to this motif, one upstream and one downstream m5CpG as well as other common residues over an ∼20-bp long region may be recognized by MDBP. © 1986 IRL Press Limited, Oxford, England.