2-Aminopurine-induced mutagenesis in T4 bacteriophage: a model relating mutation frequency to 2-aminopurine incorporation in DNA.

Abstract:

We measured the in vivo incorporation of 2-aminopurine into DNA of T4 bacteriophage allelic for gene 43 (DNA polymerase), mutator (L56), 43+, and antimutator (L141). The magnitude of incorporation (mol/mol of Thy) was 1/1500 in L56, 1/1600 in 43+, and 1/8900 in L141. The incorporation ratio L56:43+:L141 in vivo was equal to that mediated by the purified DNA polymerases of these allelic phages in vitro. A model for 2-aminopurine-induced A-T in equilibrium G-C transitions is discussed. The model is used to predict the magnitudes of replication errors (C mispairing with a template 2-aminopurine) and incorporation errors (2-aminopurine mispairing with a template C) per round of replication and to investigate the asymmetry in 2-aminopurine-induced transitions favoring the A-T leads to G-C pathway over G-C leads to A-T. We suggest that the fidelity of L56 and L141 DNA polymerases exemplifies one-step and two-step editing, respectively.

Polymerases:

Topics:

Mutational Analysis, Nucleotide Analogs / Template Lesions, Fidelity, Nucleotide Incorporation, Exonuclease Activity

One line summary:

Mutator polymerases undergo a one-step proofreading process, while antimutator polymerases undergo two.

Status:

new topics/pols set partial results complete validated

Results:

Polymerase Reference Property Result Context
T4 A89TD363N Goodman MF1977 Nucleotide Substitution Rate 100 Mutation frequency (relative to WT) Technique: T4 rII 199oc reversion assay (Spontaneous)
T4 A89TD363N Goodman MF1977 Nucleotide Substitution Rate 5 Mutation frequency (relative to WT) Technique: T4 rII 199oc reversion assay (AP-induced)
T4 A89TD363N Goodman MF1977 Nucleotide Substitution Rate 3.8 Mutation frequency (relative to WT) Technique: T4 rII 199oc reversion assay (dCMP-AP mismatch)
T4 A737V Goodman MF1977 Nucleotide Substitution Rate 0.002 Mutation frequency (relative to WT) Technique: T4 rII 199oc reversion assay (spontaneous)
T4 A737V Goodman MF1977 Nucleotide Substitution Rate 0.0025 Mutation frequency (relative to WT) Technique: T4 rII 199oc reversion assay (AP-induced)
T4 A737V Goodman MF1977 Nucleotide Substitution Rate 0.01 Mutation frequency (relative to WT) Technique: T4 rII 199oc reversion assay (dCMP-AP mismatch)

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