Send to

Choose Destination
See comment in PubMed Commons below
J Biol Chem. 1980 Nov 25;255(22):10569-71.

Repair of alkylated DNA in Escherichia coli. Methyl group transfer from O6-methylguanine to a protein cysteine residue.


O6-Methylguanine residues disappear from alkylated DNA by an inducible repair process in Escherichia coli. The reaction can be studied in a cell-free system, using DNA treated with a radioactive methylating agent as substrate. The disappearance of labeled O6-methylguanine from DNA is not accompanied by release of radioactive material in an acid-soluble form. Instead, the methyl group of O6-methylguanine appears to be transferred enzymatically to a protein cysteine residue. Radioactively labeled S-methylcysteine has been identified in protein hydrolysates after incubation of the alkylated DNA with a partly purified E. coli methyltransferase activity. The radioactive amino acid residue shows properties identical with those of S-methylcysteine by automatic amino acid analysis and paper chromatography in several solvent systems. Moreover, oxidation of the compound with hydrogen peroxide yields a product which co-chromatographs with S-methylcysteine sulfone.

[PubMed - indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk