Involvement of phenylalanine 272 of DNA polymerase beta in discriminating between correct and incorrect deoxynucleoside triphosphates

The F272L mutator mutant of polymerase beta was characterized. To determine the function of the F272 residue in maintaining polymerase beta fidelity, the in vivo and in vitro spontaneous mutation frequencies of the F272L variant were measured and a mutation spectrum was generated. Results indicated that F272L has a spontaneous mutation frequency that is 10-times greater than wild-type DNA polymerase beta and that phenylalanine 272 is essential for fidelity during ground-state binding.