Characterization of DBPm, a plant protein that binds to DNA containing 5-methylcytosine.
A protein (DBPm) has been isolated from nuclear extracts of soybean seeds, cauliflower florets, corn seed, wheat germ, and pea hypocotyl, seeds, apices, roots, and leaves that specifically binds to double-strand DNA containing 5-methylcytosine residues. In electrophoretic mobility shift assays, non-methylated duplex DNAs competed only slightly, while methylated DNAs were strong competitors. Specific binding still occurred after partial proteolysis of DBPm, but not after heating at 45 degrees C. By ultraviolet light-crosslinking and sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration, the size of pea seed DBPm was estimated to be in the range 70-90 kDa. From equilibrium binding studies the equilibrium constant for binding of pea seed DBPm to a 34 bp duplex deoxyoligonucleotide containing 12 5-methylcytosine residues was 1.2 x 10(9) M-1. The binding properties of DBPm make it a good candidate for a plant protein capable of mediating the effects of DNA methylation on the activity of some plant genes.
Ehrlich
K C
KC
Southern Regional Research Center, U.S. Department of Agriculture, New Orleans, LA 70179.
D044503:5-Methylcytosine; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism*; D003596:Cytosine / Q000031:analogs & derivatives*; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D010940:Plant Proteins; D044503:5-Methylcytosine; D003596:Cytosine; D004247:DNA