Recognition of the nonpolar base 4-methylindole in DNA by the DNA repair adenine glycosylase MutY

The DNA repair adenine glycosylase MutY efficiently recognizes 7-deaza-2'-d eoxyadenosine (Z) and its nonpolar isostere 4-methylindole beta-deoxynucleo side (M) opposite 7,8-dihydro-8-oxo-2'-deoxyguanosine (OG) and G in DNA. Bo th wild-type and truncated MutY exhibit a 10- to 20-fold higher affinity fo r a duplex containing OG:M than OG:Z, More efficient recognition of M over Z by MutY may be to due the lack of hydrogen bonding with the OG that facil itates nucleotide flipping during the substrate recognition process.