Non-C-G recognition sequences of DNA cytosine-5-methyltransferase from rat liver.
The eukaryotic DNA cytosine-5-methyltransferase (E.C.2.1.1.37) is known to methylate cytosine in DNA mainly, but not exclusively in C-G. In the present study the minor, non-C-G recognition sequences of a rat DNA methyltransferase were analyzed by Maxam-Gilbert sequencing of in vitro methylated SV40 DNA. The enzyme methylates C-A and C-T at a 50-fold lower initial rate than C-G. Methylation of C-C at the 5'C was not observed in the piece of DNA sequenced. The methylation of C-A is very low in the trinucleotides ACA and CAC, the other C-A containing trinucleotides in DNA are much better methylacceptors. C-T was found methylated predominantly in the sequences CCTAA, ACTAA, and ACTGT. A comparison of the activity with different substrates is in favour of the enzyme making its recognition in the major groove of the DNA.
Hubrich-Kühner
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K
Robert Koch-Institut, Berlin, Federal Republic of Germany.
Buhk
H J
HJ
Wagner
H
H
Kröger
H
H
Simon
D
D
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D003596:Cytosine / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008745:Methylation; D008979:Moloney murine leukemia virus / Q000235:genetics; D011119:Polynucleotides / Q000378:metabolism; D051381:Rats; D013539:Simian virus 40 / Q000235:genetics; D013379:Substrate Specificity
D004279:DNA, Viral; D011119:Polynucleotides; D003596:Cytosine; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases