The pH-dependent mismatch formation by DNA polymerase eta.

To clarify the molecular mechanism of mismatch formation by DNA polymerase eta, the pH-dependency of misincorporation of dNTP was studied with the synthetic template-primer. Incorporation of dNTP formed Watson-Crick type base pair, such as the incorporation of dATP opposite template T, was slightly affected by pH between 6.5 to 9.0. On the other hand, the misincorporation rate of dGTP opposite template T by DNA polymerase eta was drastically increased according to the increasing pH. Kinetical analysis revealed that this change might be due to the change of Km value for dGTP rather than that of Vmax value. This suggests that the affinity of dGTP on DNA polymerase eta during the mismatch formation with template T should be affected by pH.