1-methyl G (1meG)

FULL NAME: 1-methylguanie


DESCRIPTION:
1meG is a very strong block to replication, which can be partially overcome when the DNA lesion is partially repaired by AlkB; lesion bypass of 1meG in vivo increases 8-fold from 2% in AlkB− cells to 16% in AlkB+ cells. Similarly, AlkB causes a reduction in the mutagenicity of 1MeG from a very high frequency of 80% in AlkB− cells to 4% in AlkB+ cells. Taken together, these data indicate that AlkB is a powerful protection against the mutagenic activity of this dangerous alkylated base. The mutational fingerprint of 1meG reveals G → T (57% of all progeny), G → A (17%) and G → C (6%) mutations. In many instances, the induction of the SOS bypass polymerases results in increased bypass of a given lesion at the expense of reduced fidelity at the site of damage; however, the SOS polymerases are somewhat anti-mutagenic when they bypass this modified base.

DAMAGE TYPE: methylation damage


DNA DAMAGE SOURCE(S) (MAIN):
methyl methanesulfonate (MMS)
alkylating agents


DNA DAMAGE EFFECT(S) (MAIN):
G→A transition
G→T transversion
mutagenesis
point mutation
substitution
transition
transversion


DNA DAMAGE EFFECT(S) (MINOR):
G→C transversion
mutagenesis
point mutation
substitution
transversion


PATHWAYS:
base excision repair (BER)
direct reversal (DR)


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


Last modification date: Nov. 17, 2011