Inactivation of de novo DNA methyltransferase activity by high concentrations of double-stranded DNA.
The activity of eukaryotic DNA methyltransferase diminishes with time when the enzyme is incubated with high concentrations (200-300 micrograms/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.
Palitti
F
F
Department of Biochemical Sciences, University of Rome La Sapienza, Italy.
Carotti
D
D
Grünwald
S
S
Rispoli
M
M
Whitehead
E P
EP
Salerno
C
C
Strom
R
R
Drahovsky
D
D
D004247:DNA / Q000378:metabolism / Q000494:pharmacology*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism / Q000494:pharmacology; D004277:DNA, Single-Stranded / Q000378:metabolism / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D008837:Micrococcus / Q000235:genetics; D011089:Polydeoxyribonucleotides / Q000378:metabolism / Q000494:pharmacology
D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D011089:Polydeoxyribonucleotides; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases