Beyond translesion synthesis: polymerase ? fidelity as a potential determinant of microsatellite stability.

ABSTRACT: Microsatellite DNA synthesis represents a significant component of human genome replication that must occur faithfully. However, yeast replicative DNA polymerases do not possess high fidelity for microsatellite synthesis. We hypothesized that the structural features of Y-family polymerases that facilitate accurate translesion synthesis may promote accurate microsatellite synthesis. We compared human polymerases ? (Pol ?) and ? (Pol ?) fidelities to that of replicative human polymerase ? holoenzyme (Pol ?4), using the in vitro HSV-tk assay. Relative polymerase accuracy for insertion/deletion (indel) errors within 2-3 unit repeats internal to the HSV-tk gene concurred with the literature: Pol ?4 >> Pol ? or Pol ?. In contrast, relative polymerase accuracy for unit-based indel errors within [GT](10) and [TC](11) microsatellites was: Pol ? ? Pol ?4 > Pol ?. The magnitude of difference was greatest between Pols ? and ?4 with the [GT] template. Biochemically, Pol ? displayed less synthesis termination within the [GT] allele than did Pol ?4. In dual polymerase reactions, Pol ? competed with either a stalled or moving Pol ?4, thereby reducing termination. Our results challenge the ideology that pol ? is error prone, and suggest that DNA polymerases with complementary biochemical properties can function cooperatively at repetitive sequences.

SUBMITTER: Hile SE 

PROVIDER: S-EPMC3287198 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature