Inactivation of de novo DNA methyltransferase activity by high concentrations of double-stranded DNA |
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| Authors: | F. Palitti, D. Carotti, S. Grü nwald, M. Rispoli, E.P. Whitehead, C. Salerno, R. Strom,D. Drahovsky |
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| Affiliation: | 1. Department of Biochemical Sciences, University of Rome ‘La Sapienza’, Rome, Italy;2. Department of Human Biopathology, University of Rome ‘La Sapienza’, Rome, Italy;3. C.N.R. Center for Molecular Biology, Rome, Italy;4. Laboratory of Biochemical and Clinical Analyses, University of Chieti Italy;5. Commission of the European Communities, Biology Division, Frankfurt F.R.G.;6. Zentrum der Biologischen Chemie, Frankfurt F.R.G.;7. Zentrum der Inneren Medizin, Frankfurt University, Frankfurt F.R.G. |
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| Abstract: | The activity of eukaryotic DNA methyltransferase diminishes with time when the enzyme is incubated with high concentrations (200–300 μg/ml) of unmethylated double-stranded Micrococcus luteus DNA. Under similar conditions, single-stranded DNA induces only a limited decrease of enzyme activity. The inactivation process is apparently due to a slowly progressive interaction of the enzyme with double-stranded DNA that is independent of the presence of S-adenosyl-l-methionine. The inhibited enzyme cannot be reactivated either by high salt dissociation of the DNA-enzyme complex or by extensive digestion of the DNA. Among synthetic polydeoxyribonucleotides both poly(dG-dC) · poly(dG-dC) and poly(dA-dT) · poly(dA-dT), but not poly(dI-dC) · poly(dI-dC), cause inactivation of DNA methyltransferase. This inactivation process may be of interest in regulating the ‘de novo’ activity of the enzyme. |
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| Keywords: | DNA methyltransferase inactivation Enzyme inactivation dsDNA (Human transferase) (Micrococcus DNA) |
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