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Mouse DNA‐cytosine‐5‐methyltransferase: sequence specificity of the methylation reaction and electron microscopy of enzyme‐DNA complexes.
Author(s) -
Pfeifer G.P.,
Spiess E.,
Grünwald S.,
Boehm T.L.,
Drahovsky D.
Publication year - 1985
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1985.tb04017.x
Subject(s) - dna methyltransferase , dna methylation , biology , dna , microbiology and biotechnology , methyltransferase , cytosine , methylation , biochemistry , gene , gene expression
Monoclonal antibodies prepared against DNA methyltransferase from human placenta undergo immune complex formation also with DNA methyltransferase from P815 mouse mastocytoma cells. One of these monoclonal antibodies, M2B10, was used for the immunoaffinity purification of this enzyme. Complexes of the immunoaffinity‐purified mouse DNA methyltransferase with DNA were visualized by electron microscopy. DNA methyltransferase was found to be distributed along linearized plasmid DNA with a higher incidence of enzyme molecules at the terminal segments. This binding to strand ends was significantly increased after dG‐ or dGdC‐tailing of the DNA, which is compatible with a preferred binding of the enzyme to single‐stranded DNA. Sequence specificity analysis using methyl‐sensitive restriction enzymes showed that the mouse DNA methyltransferase transferred methyl groups to the internal cytosines in 5′CCGG and 5′GCGC sequences, however, the external cytosine in 5′CCGG sequences was also methylated.