Alleviation of C⋅C Mismatches in DNA by the Escherichia coli Fpg Protein.

ABSTRACT: DNA polymerase III mis-insertion may, where not corrected by its 3'→ 5' exonuclease or the mismatch repair (MMR) function, result in all possible non-cognate base pairs in DNA generating base substitutions. The most thermodynamically unstable base pair, the cytosine (C)⋅C mismatch, destabilizes adjacent base pairs, is resistant to correction by MMR in Escherichia coli, and its repair mechanism remains elusive. We present here in vitro evidence that C⋅C mismatch can be processed by base excision repair initiated by the E. coli formamidopyrimidine-DNA glycosylase (Fpg) protein. The k _cat for C⋅C is, however, 2.5 to 10 times lower than for its primary substrate 8-oxoguanine (oxo⁸G)⋅C, but approaches those for 5,6-dihydrothymine (dHT)⋅C and thy

SUBMITTER: Tesfahun AN 

PROVIDER: S-EPMC8278400 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature