Reaction: DNA (containing 6-O-methylguanine) + protein L-cysteine = DNA (without 6-O-methylguanine) + protein S-methyl-L-cysteine
Systematic name: DNA-6-O-methylguanine:[protein]-L-cysteine S-methyltransferase
Comments: This protein is involved in the repair of alkylated DNA. It acts only on the alkylated DNA (cf. EC 126.96.36.199, DNA-3-methyladenine glycosidase I and EC 188.8.131.52, DNA-3-methyladenine glycosidase II). This enzyme catalyses only one turnover and therefore is not strictly catalytic.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 77271-19-3
1. Foote, R.S., Mitra, S. and Pal, B.C. Demethylation of O6-methylguanine in a synthetic DNA polymer by an inducible activity in Escherichia coli. Biochem. Biophys. Res. Commun. 97 (1980) 654-659. [PMID: 81133635]
2. Olsson, M. and Lindehl, T. Repair of alkylated DNA in Escherichia coli. Methyl group transfer from O6-methylguanine to a protein cysteine residue. J. Biol. Chem. 255 (1980) 10569-10571. [PMID: 81046903]
3. Pegg, A.E. and Byers, T.L. Repair of DNA containing O6-alkylguanine. FASEB J. 6 (1992) 2302-2310. [PMID: 92184065]