A DNA methyltransferase partly purified from human placenta has been tested on a variety of synthetic polydeoxynucleotides. The results showed that: (i) the enzyme is most active as a 'maintenance' or 'hemi-' methylase but also has some de novo methylating activity; (ii) the presence or absence of A or T in the substrate strand has little influence on maintenance or de novo activity, while polymers containing C but not G in the same strand are poor de novo substrates and bind poorly to the enzyme; (iii) single-stranded polymers are about as good substrates as double-stranded ones, and the effects of nucleotide composition (particularly G and mC content) on enzyme activity with single strands are similar to those with double-stranded polymers; (iv) strands in which all the cytosines are methylated bind the enzyme well. A mechanism is suggested involving two different sites on the enzyme that recognize CG and mCG, and which rationalizes the activity of eukaryotic DNA methyltransferases towards single-stranded DNA. © 1986.
SUBSTRATE PREFERENCES OF HUMAN PLACENTAL DNA METHYLTRANSFERASE INVESTIGATED WITH SYNTHETIC POLYDEOXYNUCLEOTIDES / Carotti, Daniela; Palitti, Franco; Stefania, Mastrantonio; Matilde, Rispoli; Strom, Roberto; Antonio, Amato; Francesco, Campagnari; Edward P., Whitehead. - In: BIOCHIMICA ET BIOPHYSICA ACTA. - ISSN 0006-3002. - STAMPA. - 866:2-3(1986), pp. 135-143. [10.1016/0167-4781(86)90110-7]
SUBSTRATE PREFERENCES OF HUMAN PLACENTAL DNA METHYLTRANSFERASE INVESTIGATED WITH SYNTHETIC POLYDEOXYNUCLEOTIDES
CAROTTI, Daniela;PALITTI, Franco;STROM, Roberto;
1986
Abstract
A DNA methyltransferase partly purified from human placenta has been tested on a variety of synthetic polydeoxynucleotides. The results showed that: (i) the enzyme is most active as a 'maintenance' or 'hemi-' methylase but also has some de novo methylating activity; (ii) the presence or absence of A or T in the substrate strand has little influence on maintenance or de novo activity, while polymers containing C but not G in the same strand are poor de novo substrates and bind poorly to the enzyme; (iii) single-stranded polymers are about as good substrates as double-stranded ones, and the effects of nucleotide composition (particularly G and mC content) on enzyme activity with single strands are similar to those with double-stranded polymers; (iv) strands in which all the cytosines are methylated bind the enzyme well. A mechanism is suggested involving two different sites on the enzyme that recognize CG and mCG, and which rationalizes the activity of eukaryotic DNA methyltransferases towards single-stranded DNA. © 1986.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
