On the mechanism of DNA-adenine methylase.
Experiments were performed to determine whether EcoRI methylase catalyzes the transfer of the methyl group of S-adenosylmethionine (a) directly to the N6 of adenine in DNA or (b) initially to N1 to give N1-methyladenine followed by isomerization of the N1-methylamino and 6-NH2 to give N6-methyladenine (Dimroth rearrangement). A facile synthesis of highly enriched [6-15N]deoxyadenosine and a dodecamer substrate of EcoRI methylase with [6-15N]adenine in the methylation site are reported. In the product of EcoRI enzymatic methylation, all of the isotope remains at the N6 position of the N6-methyladenine product. It is concluded that, contrary to existing chemical precedent, the methylation occurs by direct transfer from S-adenosylmethionine to the N6 of adenine in DNA.
Pogolotti
A L
AL
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Ono
A
A
Subramaniam
R
R
Santi
D V
DV
D000225:Adenine / Q000031:analogs & derivatives / Q000378:metabolism; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D003839:Deoxyadenosines / Q000378:metabolism; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008780:Methyltransferases / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)
D000225:Adenine; D003839:Deoxyadenosines; D008780:Methyltransferases; D012436:S-Adenosylmethionine; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C000730567:6-methyladenine