N3-methyl G (3meG)

FULL NAME: 3-methylguanine


DESCRIPTION:
N3-methylguanine (3MeG) is thought to block replication in the same way as 3MeA does, but it is formed in DNA at a 15-fold lower level. The half-life of 3MeG in vivo has been shown to be 3–4 hours. It has been shown that E.coli alkA mutants are sensitive to alkylating agents even though they express Tag, which repairs 3MeA (a known cytotoxic lesion) as efficiently as AlkA on double-stranded DNA. This result suggests that 3MeG contributes to the toxic effects of alkylation seen in these cells. Using cell extracts from adapted E.coli, it was shown that the AlkA protein can repair 3MeG present on methylated DNA in vitro. The same study also shows persistence of this adduct in unadapted E.coli 30 min after exposure to MNNG. A second in vitro study has shown that TAG also repairs 3MeG present on a synthetic G:C-rich double-stranded DNA sequence, albeit with an efficiency of only 1/70th that of AlkA. CAS No.2958-98-7 CHEBI:1604 Kegg COMPOUND: C02230

DAMAGE TYPE: methylation damage


DNA DAMAGE SOURCE(S) (MAIN):
N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)
SN1 methylating agents
SN2 methylating agents
methyl methanesulfonate (MMS)
alkylating agents


DNA DAMAGE EFFECT(S) (MAIN):
cytotoxic
stalled replication fork


PATHWAYS:
base excision repair (BER)


DNA repair protein(s) related to damage:
AlkA
Tag
ANPG (MPG)


Last modification date: Sept. 1, 2011